EA048164B1 - STABLE DOSAGE FORM OF CETRORELIX ACETATE FOR PARENTERAL ADMINISTRATION - Google Patents

Abstract

The invention relates to a stable dosage form for parenteral administration containing a ready-to-inject sterile, stable aqueous solution of cetrorelix acetate. The invention also relates to an injection device pre-filled with a ready-to-inject sterile, stable aqueous solution of cetrorelix acetate. The invention relates to a method for suppressing the premature surge of luteinizing hormone in women undergoing controlled ovarian stimulation, comprising a stable dosage form for parenteral administration containing a ready-to-inject sterile, stable aqueous solution of cetrorelix acetate.

Description

Field of technology

The present invention relates to a stable dosage form for parenteral administration with a ready-to-inject sterile stable aqueous solution of cetrorelix acetate. The present invention also relates to an injection device pre-filled with a ready-to-inject sterile stable aqueous solution of cetrorelix acetate. The present invention relates to a method for suppressing premature luteinizing hormone surge in women undergoing controlled ovarian stimulation, comprising a stable dosage form for parenteral administration with a ready-to-inject sterile stable aqueous solution of cetrorelix acetate.

State of the art

Cetrorelix is a gonadotropin-releasing hormone antagonist (GnRH antagonist), acetyl-O-3-(2'-naphthyl)alanine-O-4-chlorophenylalanine-3-(3'-pyridyl)alanine-L-serine-tyrosine-citrulline-leucine-arginine-proline-alanine-amide ( _{C70H92ClN17O14} ), characterized by the following formula. It is a decapeptide with _a terminal _amide group. It acts by blocking the action of GnRH on the pituitary _gland , thus providing rapid suppression of the production and action of luteinizing hormone and follicle-stimulating hormone:

For parenteral administration, aqueous solutions of peptides are required. However, aqueous solutions of peptides such as cetrorelix are subject to chemical degradation. They are also prone to aggregation, resulting in increased turbidity or cloudiness of the solution upon storage.

The first product on the market was Cetrotide®. It is available as a lyophilized powder in glass vials containing 0.25 or 3 mg of cetrorelix. A pre-filled glass syringe containing 1 or 3 ml of sterile water for injection is provided separately, and the solution is prepared only before injection. Thus, the first product provided a solution to the problem of degradation in aqueous solution, simply by avoiding the preparation of a dosage form containing an aqueous solution that must be stored for a long time. Instead, the water was removed and a lyophilisate was prepared to avoid instability problems. However, this solution to the problem has obvious disadvantages: (1) it is an expensive and time-consuming process; (2) the product is not ready for injection and requires reconstitution before administration; and (3) the reconstituted solution is stable only for a short period of time. Thus, Cetrotide® did not meet the need for a ready-to-inject aqueous solution.

U.S. Patent No. 7,718,599 discloses that aqueous solutions of cetrorelix are prone to aggregation. Liquid crystalline structures were observed under a polarized light microscope. Gluconic acid was added to solutions of cetrorelix acetate (2.5 mg/mL), and at gluconic acid concentrations less than 0.07%, resulting in a pH of 3.7, aggregation was observed within 2 days. At pH greater than 3.7, a similar problem was reported. When the gluconic acid concentration was increased to 0.71%, resulting in a pH of 3.1, aggregation was observed after 12 days, indicating that higher concentrations of gluconic acid, and therefore lower pH, resulted in improvement. A disadvantage of this method is that the degree to which the aggregation problem is resolved depends on the concentration of gluconic acid, and the more gluconic acid, the lower the pH. However, US Patent No. 7,718,599 does not report the effect of pH on the chemical stability of cetrorelix. In addition, formulations that did not show aggregation during long-term storage stability studies were not provided. US Patent No. 2013/0303464 describes a ready-to-use aqueous formulation of cetrorelix containing cetrorelix acetate, glacial acetic acid, a tonicity adjusting agent, and water for injection. A suitable pH was illustrated in working examples in which the pH was approximately 3. The preferred pH of the present invention was from 2.8 to 3.5.

U.S. Patent No. 7,214,662 describes aqueous solutions of peptides, including cetrorelix acetate, and proposes solutions to the problem of aggregation. This document shows that carboxylic acids and especially hydroxycarboxylic acids, preferably gluconic acid, in combination with a surfactant provide a reduction in aggregation. The use of a carboxylic acid according to U.S. Patent No. 7,214,662 resulted in a low pH, for example a pH of 2.5 to 3.

Description of the invention

The objective of the present invention is to provide a dosage form for parenteral administration.

- 1 048 164 administration, containing a ready-to-inject sterile stable aqueous solution of cetrorelix acetate. Another object of the present invention is to provide an injection device pre-filled with a sterile stable aqueous solution of cetrorelix acetate. As used herein, the term ready-to-inject refers to a ready-to-inject, sterile stable aqueous solution of cetrorelix acetate that is suitable for direct subcutaneous or intramuscular administration, i.e. it is ready for injection and does not require reconstitution or dilution prior to injection. In particular, another objective is that the sterile, stable aqueous solution of cetrorelix acetate dispensed into an injection device that is ready for injection is not only physically stable in terms of controlling the development of aggregation or turbidity, but is also chemically stable such that the level of impurities remains low while the parenteral dosage form is stored on the shelf and until it is administered to the patient subcutaneously or intramuscularly.

Degradation of peptides may result in the formation of other peptides and/or peptide derivatives, which themselves may be characterized by pharmacological activity. Therefore, more specifically, the task was to develop a suitable method for separating individual impurities and their quantitative determination. The task was to limit the concentration of such impurities.

The present inventors have developed a high performance liquid chromatography (HPLC) method that yields distinct peaks for several impurities that have not been previously reported in the prior art. While the prior art claimed that low pH values were necessary to reduce the tendency to agglomerate, the present inventors found using their HPLC method that in the parenteral dosage form of the present invention, a pH of 3 to 5 was optimal with respect to chemical stability in terms of impurity increase over time, and that an aqueous solution of cetrorelix acetate could be prepared at this higher pH without agglomeration problems.

The new impurity discovered by the present inventors was impurity A, represented by a compound of formula I given below:

Formula I.

Impurity B is characterized by the structure represented by the compound of formula II given below:

formula II.

Impurity D is characterized by the structure represented by the compound of formula III given below:

Impurity F is characterized by the structure represented by the compound of formula IV given below:

- 2 048164

..' · ^: - Λ' formula IV.

In the prior art, a low pH of 3.0 was considered optimal for stability; however, in the present invention, it was found that at pH values of 2.5 to 3.0, recommended by the prior art, the level of impurity A increases significantly when the solution is stored at 25°C/60% relative humidity.

Nowhere in the prior art have compounds of formulas I, II, III and IV, i.e. impurities A, B, D and F, respectively, been identified.

The present invention shows not only the possibility of preparing a stable aqueous solution of cetrorelix acetate at a pH of 3 to 5 without agglomeration problems, but also that the level of impurity A and the total level of impurities are well controlled and remain at low concentrations when the parenteral dosage form is stored at 25°C/60% RH for at least 1 month, at least 2 months, at least 3 months or at least 6 months. The parenteral dosage form can also be stored at a temperature of 2 to 8°C with good stability for at least 24 months.

In one aspect, the present invention provides a parenteral dosage form comprising a stable aqueous solution comprising:

(i) cetrorelix or a pharmaceutically acceptable salt thereof and (ii) an impurity of formula I in an amount of less than 5% w/v of the cetrorelix base:

(formula I).

Preferably, the parenteral dosage form comprises an impurity of formula I in an amount of less than 4% w/v based on the cetrorelix base. More preferably, the parenteral dosage form comprises an impurity of formula I in an amount of less than 3% w/v based on the cetrorelix base. More preferably, the parenteral dosage form comprises an impurity of formula I in an amount of less than 2% w/v based on the cetrorelix base. More preferably, the parenteral dosage form comprises an impurity of formula I in an amount of less than 1% w/v based on the cetrorelix base.

The dosage form for parenteral administration additionally contains an osmotic agent and water for injection.

In a preferred aspect, the present invention provides a dosage form for parenteral administration comprising a stable aqueous solution containing:

(i) cetrorelix or a pharmaceutically acceptable salt thereof and (ii) an impurity of formula I in an amount of less than 1% w/v of the cetrorelix base, formula I.

In another aspect, the present invention provides a dosage form for parenteral administration comprising a stable aqueous solution comprising:

(i) cetrorelix or a pharmaceutically acceptable salt thereof and

- 3 048164 (ii) an impurity of formula I in an amount of less than 1% w/v of the base in the form of cetrorelix:

In another aspect, the present invention provides a dosage form for parenteral administration comprising a ready-to-inject sterile stable aqueous solution comprising:

(i) cetrorelix or a pharmaceutically acceptable salt thereof, (ii) an organic acid to adjust the pH in the range from 3 to 5, (iii) impurity A, a decapeptide of formula I, in an amount of less than 1% w/v of the cetrorelix base:

(iv) osmotic agent and (v) water for injection.

In one embodiment, the present invention provides a parenteral dosage form comprising a ready-to-inject sterile stable aqueous solution that contains:

(i) cetrorelix or a pharmaceutically acceptable salt thereof, (ii) an organic acid to adjust the pH in the range from 3 to 5, (iii) impurity A, a decapeptide of formula I, in an amount of less than 1% w/v of the cetrorelix base:

OH formula I, (iv) osmotic agent and (v) water for injection.

The parenteral dosage form containing the ready-to-inject sterile stable aqueous solution of cetrorelix according to the present invention remains physically and chemically stable when stored at a temperature of 2 to 8°C for at least 1 month, at least 3 months, at least 6 months, at least 12 months, at least 18 months or at least 24 months or at room temperature (25°C/60% RH) for at least 1 month, at least 3 months or at least 6 months.

Preferred embodiments of the parenteral dosage form may be labeled with a shelf life at 2 to 8°C of at least 24 months or 24 months. More preferred embodiments of the parenteral dosage form may be labeled with a shelf life of at least 6 months or 6 months at room temperature (25°C/60% RH).

The concentration of the decapeptides of formula I (impurity A) remains in the range of 0.001 to 1.0%, preferably 0.05 to 0.5% by weight of the cetrorelix base, the maximum amount of a single unknown impurity remains at a level of less than 0.5% by weight of the cetrorelix base, and the total level of impurities remains at a level of no more than 3.5% by weight of the cetrorelix base when stored at

- 4 048164 at a temperature of 2 to 8°C for at least 1 month, at least 2 months, at least 3 months, at least 6 months, at least 12 months, at least 18 months or at least 24 months and/or at room temperature (25°C/60% RH) for at least 1 month, at least 2 months, at least 3 months or at least 6 months.

The parenteral dosage form containing the ready-to-inject sterile aqueous solution of cetrorelix according to the present invention is physically stable without aggregation, gelation or precipitation of the aqueous solution during the shelf life. Aggregation or gelation can be determined by measuring the turbidity or cloudiness of the solution. It is measured in FTU units (formazin turbidity unit) or NTU units (nephelometric turbidity unit).

The test is carried out according to the protocol described in the European Pharmacopoeia version 9.0. No aggregation or gelation is considered to be observed in the solution if the turbidity/haze value is less than or equal to 8 FTU/NTU. The higher the FTU/NTU values, the higher the degree of turbidity or haze of the solution, and vice versa. The NTU values of the ready-to-inject parenteral dosage form of the present invention remain at a level of less than 2 NTU, preferably less than 1 NTU, more preferably less than 0.5 NTU, initially and during long-term storage of the dosage form in the temperature range of 2 to 8°C for at least 1 month, at least 2 months, at least 3 months, at least 6 months, at least 12 months, at least 18 months or at least 24 months and/or at room temperature (25°C/60% RH) for at least 6 months. Thus, during the shelf life, no aggregation, gelation or precipitation in the aqueous solution is observed. Also, during storage, there is no significant increase in the viscosity of the solution.

The parenteral dosage form comprising the ready-to-inject sterile stable aqueous solution of cetrorelix according to the present invention comprises cetrorelix acetate in a concentration ranging from 0.26 to 0.28 mg/ml, which is equivalent to 0.25 mg/ml of cetrorelix base. Preferably, cetrorelix acetate is present in the ready-to-inject sterile stable aqueous solution in a concentration equivalent to 0.25 mg/ml of cetrorelix base.

In one embodiment, a parenteral dosage form comprising a ready-to-inject sterile stable aqueous solution of cetrorelix according to the present invention comprises a pH adjusting agent in a concentration sufficient to adjust the pH in the range of 3 to 6.

In a preferred embodiment, the parenteral dosage form containing the ready-to-inject sterile stable aqueous solution of cetrorelix according to the present invention contains an organic acid as a pH adjusting agent in a concentration sufficient to adjust the pH in the range of 3 to 5, more preferably in the range of 4 to 4.5. The pH of the ready-to-inject sterile stable aqueous solution of the present invention can be, for example, 3, 3.05, 3.10, 3.15, 3.20, 3.25, 3.30, 3.35, 3.40, 3.45, 3.5, 3.55, 3.60, 3.65, 3.70, 3.75, 3.80, 3.85, 3.90, 3.95, 4.00, 4.05, 4.10, 4.15, 4.20, 4.25, 4.30, 4.35, 4.40, 4.45, 4.50, 4.55, 4.60, 4.65, 4.70, 4.75, 4.80, 4.85, 4.90, 4.95, 5.00, 5.05, 5.10, 5.15, 5.20, 5.25, 5.30, 5.35, 5.40, 5.45, 5.50, 5.55 and 6 or their intermediate ranges.

The organic acid may be selected from any water-soluble organic acid suitable for parenteral administration, but is preferably acetic acid, more preferably lactic acid. For example, in the ready-to-inject sterile aqueous solution of the present invention, lactic acid may be used in a concentration in the range of about 0.013 mg/ml to 0.53 mg/ml, preferably in an amount in the range of about 0.033 mg/ml to about 0.53 mg/ml, and in intermediate ranges thereof.

Preferably, according to the present invention, the ready-to-inject sterile stable aqueous solution of cetrorelix comprises cetrorelix (base) and an organic acid in a weight ratio of from 50.47:1 to 19.23:1, preferably in a weight ratio in the range of from about 0.47:1 to 7.57:1, more preferably in a weight ratio in the range of from about 1.56:1 to 7.57:1 and in intermediate ranges thereof.

The parenteral dosage form containing a ready-to-inject sterile stable aqueous solution of cetrorelix according to the present invention contains an osmotic agent or an agent for adjusting tonicity in amounts suitable for adjusting the osmolarity of the solution in the range of about 250-375 mOsm/kg, preferably 270-330 mOsm/kg. The osmotic agent that can be used in the aqueous solution according to the present invention is selected without limitation from mannitol, glycerol, sorbitol, sodium chloride, potassium chloride, dextrose, sucrose, and the like and mixtures thereof.

According to one preferred embodiment, the osmotic agent is

- 5 048164 mannitol, and it can be used in an aqueous solution in an amount ranging from about 40.0 to 60.0 mg/mL, preferably in an amount ranging from about 50.0 to 58.0 mg/mL. In one preferred embodiment, the osmotic agent is mannitol, and it is used in a ready-to-inject sterile aqueous solution in an amount of about 55.0 mg/mL.

The ready-to-inject sterile aqueous solution in the parenteral dosage form of the present invention does not contain lactic acid in the form of its derivatives, polymer or copolymers such as polylactic acid or polylactic-glycolic acid copolymer. Lactic acid is preferably used as the only means for adjusting pH. In preferred embodiments, the ready-to-inject sterile aqueous solution does not contain surfactants such as Tween 80, polysorbates, poloxamers, spans and the like. The ready-to-inject sterile aqueous solution of the parenteral dosage form avoids the use of surfactants, complexing agents, preservatives or antioxidants for solubilization or stabilization. In certain embodiments, the solution does not contain complexing agents such as cyclodextrins, does not contain cosolvents such as alcohols or glycols, and does not contain preservatives and antioxidants.

In another aspect, the present invention provides a sterile aqueous solution of cetrorelix acetate as defined above, which remains stable for at least 1 month, preferably at least 3 months, and more preferably at least 6 months at a temperature of 25°C and a relative humidity of 60%.

In another aspect of the present invention there is provided a sterile aqueous solution of cetrorelix acetate as defined above, which remains stable for at least 1 month, preferably at least 3 months, more preferably at least 6 months, even more preferably at least 12 months or 18 months and most preferably at least 24 months at 2-8°C.

The stable parenteral dosage form containing the ready-to-inject sterile stable aqueous solution of cetrorelix according to the present invention is suitable for subcutaneous or intramuscular administration. The ready-to-inject sterile stable aqueous solution is suitable for direct subcutaneous administration, i.e. it is ready to inject or ready to self-administer, and there is no need to reconstitute or dilute it before use. The ready-to-inject sterile stable aqueous solution according to the present invention does not require lyophilization.

The stable parenteral dosage form of the present invention is suitable for self-administration and allows the patient to self-administer a small volume of an aqueous solution subcutaneously. The volume of the ready-to-inject sterile aqueous solution of cetrorelix filled into the reservoir of the injection device is from about 0.5 to 10.0 ml, preferably from 1.0 to 2.0 ml, more preferably 1.0 ml. According to one preferred embodiment, the ready-to-inject sterile stable aqueous solution of cetrorelix is filled into the reservoir of the injection device in a volume of 1.0 ml. Preferably, the parenteral dosage form of the present invention is suitable for the administration of a single dose of cetrorelix acetate. In one embodiment, the parenteral dosage form includes a filling volume of about 1.0 ml of an aqueous solution of cetrorelix acetate, suitable for self-administration as a single dose. In some embodiments, the parenteral dosage form may comprise an aqueous solution of cetrorelix with a fill volume of approximately 10.0 mL, suitable for multiple dose administration.

The injection device according to the stable parenteral dosage form of the present invention can be selected without limitation from pre-filled syringes, auto-injectors, etc. In one preferred embodiment, the injection device is a pre-filled syringe. In another preferred embodiment, the injection device is an auto-injector, such as a pen-type auto-injector. Such pre-filled syringes or auto-injectors are suitable for self-administration or automatic injection of a drug solution by patients in need thereof, which provides a user-friendly approach.

In one preferred embodiment, the injection device is a pre-filled syringe. The pre-filled syringe includes the following components: a reservoir, such as, for example, a barrel or cartridge, in which an aqueous solution is stored; a pre-attached needle attached to one end of the reservoir; a needle cap or tip cap that covers the needle and seals the opening of the needle tip, optionally a rigid shield covering the needle cap or tip cap; a piston stroke stop at the other end of the reservoir that seals and seals the aqueous solution with which the reservoir is filled; a plunger rod that is inserted into the piston stroke stop and is used to

- 6 048164 pushing the piston stroke limiter together with the solution to the end of the needle when administering the drug.

In another preferred embodiment, the injection device is an autoinjector. The autoinjector may have various designs. In one preferred design, the autoinjector comprises the following components: a central unit or housing portion suitable for holding a pre-filled syringe, wherein the syringe comprises a reservoir, such as a barrel or cartridge, in which an aqueous solution is stored, wherein the reservoir has a pre-attached needle at one end and a piston stroke limiter at the other end. The central portion of the housing may have a transparent viewing window through which the solution in the reservoir is visible. The autoinjector further comprises a front unit having a cap-like portion that holds the needle cap or the tip cap, and it may be attached to the central unit that covers the pre-attached needle and covers the opening of the needle tip. The autoinjector further comprises a rear unit that comprises a plastic rod with a spring assembly and an activation button. When self-administering an aqueous solution, first remove the cap together with the needle cap from the body part, exposing the needle, and then, after placing the body part of the autoinjector at the injection site, press the activation button, which exerts pressure on the plastic rod with the spring assembly in the direction of the piston stroke limiter, which results in the delivery of the aqueous solution through the needle to the patient.

The reservoir may be a barrel or a cartridge, such as, for example, a barrel of a pre-filled syringe or a cartridge of an auto-injector. It may be made of a material selected from glass, plastic or a polymeric material. In some preferred embodiments, the reservoir is made of glass, such as siliconized glass type I according to USP or a non-pyrogenic glass material. In other embodiments, the reservoir is made of non-glass plastic or a polymeric material selected from a cycloolefin polymer, a cycloolefin copolymer, polyolefins, styrene-polyolefin-based polymers and block copolymers, polycarbonates and the like. In one preferred embodiment, the reservoir is a glass barrel of non-pyrogenic glass for a pre-filled syringe or a glass cartridge of non-pyrogenic glass for an auto-injector.

In one or more embodiments, the reservoir may have a pre-attached needle at one end. In some other embodiments, the reservoir is needle-free and is provided with a Luer lock at one end with a device for attaching a needle to the Luer lock before use. The pre-attached needle may be made of stainless steel. The needle tip is closed with a cap or covered with a needle cap or a tip cap. The reservoir containing a sterile aqueous solution of the drug is further closed with a stroke limiter, such as a piston stroke limiter, at the other end. Such stroke limits, needle caps or tip caps provide a physical and sterile barrier from the external environment.

Preferably, the piston stroke limiter, the needle cap/tip cap or the Luer lock cap are made of a non-glass component. The non-glass component can be a rubber or an elastomeric material, such as, for example, bromobutyl rubber, chlorobutyl rubber, type II rubber according to USP, natural rubber consisting of poly-cis-1,4-isoprene, styrene butadiene rubber and the like. Other suitable materials include high-density polyethylene or low-density polyethylene or other plastic materials. In preferred embodiments, the piston stroke limiter is made of bromobutyl rubber and the needle cap or tip cap is made of natural rubber. The needle cap can be additionally closed on the outside with a rigid polypropylene shield. It protects the needle cap from damage and facilitates removal of the needle cap before injection. The injection device assembly may comprise a plunger rod that is attached to the plunger stop and is used to push the plunger stop along with the solution toward the end of the needle when the drug is administered.

Preferably, the ready-to-inject sterile, stable aqueous solution of cetrorelix is filled into the reservoir of the injection device and sealed so that there is essentially no free air space inside the reservoir. The aqueous solution in the reservoir always remains in contact with the piston stroke stop made of elastomeric or rubber material during storage. In the case of pre-filled syringes with a pre-attached needle on a stainless steel shaft, the needle being covered by a needle cap or a tip cap, the aqueous solution remains in contact with the needle and the needle cap or tip cap during storage.

The injection device may optionally be packaged or enclosed in secondary packaging. The secondary packaging may be a blister pack or an aluminum bag and/or an opaque cardboard package. A suitable oxygen absorber may optionally be placed inside the secondary packaging.

Stability testing of the dosage form for parenteral administration is carried out at

- 7 048 164 storage of the dosage form at 2-8°C and at room temperature (25°C/60% relative humidity). During stability testing, the sterile solution of cetrorelix ready for injection remains in contact with the piston stroke stop and the needle cap made of elastomeric rubber material, as well as with the pre-attached needle made of stainless steel. In preferred embodiments, the dosage form for parenteral administration containing the sterile aqueous solution of cetrorelix ready for injection according to the present invention remains physically and chemically stable for 1 year, preferably 2 years, when stored at 2-8°C and for at least 6 months at room temperature (25°C, 60% relative humidity). The concentration of impurity A remains at less than 1.0% by weight of cetrorelix base when the filled injection device is stored at room temperature (25°C/60% relative humidity) for at least 6 months and at 2-8°C for at least 24 months. The extrapolated shelf life of an aqueous solution of cetrorelix, determined by Minitab calculation for impurity A assuming levels of 1% or less, was found to be 122 months.

In one aspect, the present invention relates to a method for suppressing premature luteinizing hormone surge in women undergoing controlled ovarian stimulation, comprising a parenteral dosage form comprising a ready-to-inject sterile stable aqueous solution comprising:

(i) cetrorelix or a pharmaceutically acceptable salt thereof and (ii) an impurity of formula I in an amount of less than 5% w/v of the cetrorelix base:

Formula I.

Preferably, the stable aqueous solution contains the impurity of formula I in an amount of less than 4% w/v based on the cetrorelix base. More preferably, the stable aqueous solution contains the impurity of formula I in an amount of less than 3% w/v based on the cetrorelix base. More preferably, the stable aqueous solution contains the impurity of formula I in an amount of less than 2% w/v based on the cetrorelix base. More preferably, the stable aqueous solution contains the impurity of formula I in an amount of less than 1% w/v based on the cetrorelix base.

The stable aqueous solution additionally contains an osmotic agent and water for injection.

In one aspect, the present invention relates to a method for suppressing premature luteinizing hormone surge in women undergoing controlled ovarian stimulation, comprising a parenteral dosage form comprising a ready-to-inject sterile stable aqueous solution comprising:

(i) cetrorelix or a pharmaceutically acceptable salt thereof, (ii) impurity A, a decapeptide of formula I, in an amount of less than 1% w/v of the cetrorelix base:

hV formula I,

In one aspect, the present invention relates to a method for suppressing premature luteinizing hormone surge in women undergoing controlled ovarian stimulation, comprising a parenteral dosage form comprising a ready-to-inject sterile stable aqueous solution comprising:

(i) cetrorelix or a pharmaceutically acceptable salt thereof, (ii) impurity A, a decapeptide of formula I, in an amount of less than 1% w/v of the cetrorelix base:

- 8 048164

In one preferred aspect, the present invention relates to a method for suppressing premature luteinizing hormone surge in women undergoing controlled ovarian stimulation, comprising a parenteral dosage form comprising a ready-to-inject sterile stable aqueous solution comprising:

(i) cetrorelix or a pharmaceutically acceptable salt thereof, (ii) an organic acid to adjust the pH in the range from 3 to 5, (iii) impurity A, a decapeptide of formula I, in an amount of less than 1% w/v of the cetrorelix base:

(iv) osmotic agent and (v) water for injection.

In another aspect, the present invention provides a decapeptide of formula I

This compound is referred to in this document as impurity A because it is an impurity in cetrorelix solution.

The present invention also provides a composition comprising a decapeptide of formula I

In another aspect, the present invention provides a method of formula I by HPLC analysis, the method comprising:

identification of decapeptide

a) introducing a diluent containing water, acetonitrile and formic acid into the chromatographic system,

b) introducing a system suitability assessment solution containing cetrorelix acetate, diluent and impurity stock solution and recording the chromatogram,

c) introduction of a standard solution containing cetrorelix acetate and diluent into the chromatographic system,

d) introducing a sample containing an aqueous solution of cetrorelix acetate and a placebo preparation into the chromatographic system and

e) determination of the relative retention time and relative response factor for

- 9,048,164 peaks of impurities and cetrorelix acetate relative to the peak of cetrorelix acetate.

The present invention also provides a decapeptide of formula I identified by HPLC analysis, wherein the method comprises

1) introduction of a diluent containing water, acetonitrile and formic acid into the chromatographic system,

2) introduction of a system suitability assessment solution containing cetrorelix acetate, diluent and mother liquor of impurity, and recording of the chromatogram,

3) introduction of a standard solution containing cetrorelix acetate and diluent into the chromatographic system,

4) introduction of a sample containing an aqueous solution of cetrorelix acetate and a placebo drug into the chromatographic system and

5) determination of the relative retention time and relative response factor for the peaks of impurities and cetrorelix acetate relative to the peak of cetrorelix acetate.

Hereinafter, the present invention is more precisely described by means of examples. These examples are not intended to limit the scope of the present invention, but merely to illustrate it.

Example 1A. Identification of the decomposition product.

To study the degradation of cetrorelix, peptide-related substances of cetrorelix were prepared by a known solid-phase peptide synthesis technique. The synthesis involved coupling one amino acid at a time, sequentially starting from the C-terminal amino acid on the resin. The peptide chain was synthesized using fluorenylmethyloxycarboyl (Fmoc)/tert-butyl (Fmoc/tBu) with H₂-diisopropylcarbodiimide (DIPC) as the coupling reagent. Fmoc groups were removed by treatment with 20% piperidine in dimethylformamide. The resin-derived peptide was finally cleaved using trifluoroacetic acid to afford related substances, which were then purified by reverse-phase high-performance liquid chromatography (RP-HPLC) on a C18 silica gel column using an acetonitrile/water gradient containing 0.1% trifluoroacetic acid. The purified peptide related substances were lyophilized to afford pure solid form. The structure of these related substances was characterized by proton NMR, carbon NMR, mass spectroscopy and elemental analysis and they were designated as impurities A, B, D and F.

Impurity A: Ac-2-D-Nal-4-Cl-D-Phe-3-D-Pal-Ser-Tyr-D-Cit-Leu-Arg-Pro-D-Ala-OH (detailed structure is described as compound of formula I).

Impurity B: 2-D-Nal-4-Cl-D-Phe-3-D-Pal-Ser-Tyr-D-Cit-leu-Arg-Pro-D-Ala-NH2 (detailed structure is described as compound of formula II).

Impurity D: Ac-2-D-Nal-4-Cl-D-Phe-3-D-Pal-Ser-Tyr-D-Cit-Leu-OH (the detailed structure is described as compound of formula III).

Impurity F: Ac-2-D-Nal-4-Cl-D-Phe-3-D-Pal-Ser-Tyr-D-Cit-Leu-Arg-Pro-OH (the detailed structure is described as compound of formula IV).

The degradation peaks resolved on the HPLC column were found to correspond to these compounds based on their relative retention times. Details of the HPLC method are provided in Example 1B.

Example 1B.

Cetrorelix and the identified impurities, namely Impurity A, Impurity B, Impurity D and Impurity F, from aqueous solution samples were separated on a reversed phase (C-18) column using a gradient technique (column: X-Select CHS C18, 150x4.6 mm, 2.5 μm (from Waters, Ireland, catalog number: 186006729) and detected and quantified using ultraviolet spectroscopy at a wavelength of 225 nm. The mobile phase was passed at a flow rate of 0.7 ml/min, and 1.0 ml/min. The chromatogram run time was 150 min.

Details regarding the mobile phase.

Mobile phase A: a mixture of the buffer solution indicated below with acetonitrile and tetrahydrofuran in a ratio of (700:280:20), degassed using ultrasound.

Mobile phase B: a mixture of the buffer solution indicated below with acetonitrile and tetrahydrofuran in a ratio of (500:480:20), degassed using ultrasound.

Buffer: 2.5 g ammonium dihydrogen orthophosphate and 0.75 g sodium 1-octanesulfonic acid in 1000 ml water with pH adjusted to 8.0±0.05 using triethylamine.

Diluent: a mixture of water, acetonitrile and formic acid in a ratio of (700:300:1).

- 10 048164

Table 1

Details regarding gradient elution

Time (minutes) Flow rate Mobile phase A (% v/v) Mobile phase B (% v/v) 0 0,7 100 0 65 0,7 100 0 75 0,7 0 100 76 1,0 0 100 135 1,0 0 100 136 0,7 100 0 150 0,7 100 0

Obtaining a mother liquor of impurities.

3.125 mg each of impurity A, impurity B, impurity D and impurity F were placed in a 50 mL volumetric flask and dissolved in approximately 5 mL of diluent using ultrasound, followed by making up to the mark with diluent.

Obtaining a solution to assess the suitability of the system.

It was prepared by weighing and transferring approximately 12.5 mg of cetrorelix acetate working standard into a 100 mL volumetric flask and dissolving it in approximately 50 mL of diluent by sonication, followed by adding approximately 2 mL of impurity stock solution and making up to the mark with diluent.

Preparation of a standard solution of cetrorelix acetate.

The standard solution of cetrorelix acetate was prepared by weighing and transferring 20 mg of the working standard of cetrorelix acetate into a 250 ml volumetric flask, dissolving it in approximately 50 ml of diluent by sonication and making up to the mark with diluent. 2 ml of this solution was transferred to a 250 ml volumetric flask and made up to the mark with diluent while stirring.

Obtaining a test solution.

An aqueous solution of cetrorelix acetate from approximately 10 pre-filled syringes of the sample to be tested (prepared according to the example described above) was mixed in a container. The solution contained cetrorelix acetate, an organic acid, an osmotic agent and water for injection. Approximately 5.0 ml of this solution was accurately transferred to a 10 ml volumetric flask, approximately 3 ml of diluent was added and the solution was sonicated for 5 min with intermediate shaking. The volume was made up to the mark with diluent while stirring.

The placebo was prepared by accurately transferring approximately 5.0 ml of the placebo solution into a 10 ml volumetric flask, adding approximately 3 ml of the diluent and sonicating for 5 min with intermediate shaking. The volume was made up to the mark with the diluent while stirring. Two replicates of 50 μl of the diluent were injected into the chromatographic system as a control. Then the system suitability solution was injected and the chromatogram was recorded. The separation level between impurity D and impurity F was at least 2.0. The standard solution was then injected in six replicates. The sample and placebo preparation were then injected into the chromatographic system.

The relative retention times and relative response factors for the peaks of cetrorelix acetate and impurities A, B, D and F relative to the peak of cetrorelix acetate are presented in Table 2.

Table 2

Name of the connection Retention time (minute) Relative retention time Cetrorelix 42.3 1,00 Impurity A 23.5 0.55 Impurity B 56.8 1.34 Impurity D 16.9 0.39 Impurity F 20.3 0.48

The percentages of impurities A, B, D, F, and unknown impurities were calculated, excluding peaks from the diluent and placebo. The sum of all known and unknown impurities gives the total impurity in %.

% of identified impurities (A, B, D, F) were calculated using the following formula:

A1 x WS x 2 x 10 x P x 1

AS 250 250 V LC RRF, where A1 = peak response of each known impurity in the chromatogram of the test product,

AS = mean peak response of cetrorelix in the chromatogram of the standard preparation,

WS = weight of working standard cetrorelix acetate in mg,

V = volume of the sample taken in ml,

P = % activity of the working standard of cetrorelix (based on as is),

LC = label declared content of cetrorelix in mg per ml (0.25 mg/ml),

- 11 048164

RRF = relative response factor for each impurity peak. % unknown impurity was calculated using the following formula:

A1 x WS x 2 x 10 x P

AS 250 250 V LC, where A1 = peak response of each unknown impurity in the chromatogram of the test product, AS = average peak response of cetrorelix in the chromatogram of the standard product, WS = weight of the working standard cetrorelix acetate in mg,

V = volume of the sample taken in ml,

P = % activity of the cetrorelix working standard (as is basis), LC = label declared cetrorelix in mg per ml (0.25 mg/ml). Total impurities (%) = sum of % known impurities and % unknown impurities.

Table 3

Compound

Examples of the present invention Comparative examples Example numbers 1 1 3 4 5 6 7 8 9 10 11 12 13 14 11sh redisities Kolnchssnu (mg mp The amount of uejpopc. niKca acetate. expressed relative to the base in the form uc I pope:ixa 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 Manni I 54.8 54.8 54.8 54.8 54.8 54.8 54.8 54.8 54.8 54.8 54.8 54.8 54.8 54.8 Lactic acid! In sufficient quantity to adjust pH _R n 3 p,1 |3,2 |3,3 |3,4 |3,5 [4 |4,5 (5 |2.5 |2.6 |2.7 |2.8 |2.9 Water for NNSCTs In sufficient quantity to obtain 1 ml

Method of obtaining.

Water for injection was taken at a temperature of 2 to 8 °C in a vessel. Mannitol was added and gradually dissolved in water for injection with stirring until a clear solution was obtained. Cetrorelix acetate was added to the resulting solution and gradually dissolved with stirring. The pH of the solution was checked and adjusted to the pH indicated in Table 3 for each example of the present invention and comparative examples, using a certain amount (volume) of 0.1% w/v lactic acid solution. The volume was brought to the mark with water for injection. The solutions were stirred for 10-15 minutes. The solutions from the examples were filtered under aseptic conditions through a layer of membrane filter with a pore size of 0.2 μm. The solution was aseptically filled into the reservoir of the injection device, i.e., the barrel of a 1 ml glass syringe with a filling volume of 1.1 ml. The pre-attached needle in the barrel was sealed with an elastomeric needle cap, which was closed with a rigid cap before filling. After filling, the glass syringe (barrel) was sealed with a piston stroke stopper using a vacuum stopper such that essentially no free air space remained inside the syringe. The aqueous solution during storage remains in contact with the piston stroke stopper made of rubber, the pre-attached needle made of stainless steel, and the needle cap made of natural rubber.

The ready-to-inject aqueous solution of Working Examples 1-9 and Comparative Examples 10-14 was subjected to chemical analysis at different stages. Initially, the % content of cetrorelix in the solution before and after filtration was analyzed by the HPLC method described above. The change in the % content in the chemical analysis before and after filtration was determined.

The solutions of the examples contained in glass syringes were then subjected to a storage stability test. The % content, the level of degradation products such as compounds of formulae I, II, III and IV, and the level of unknown impurities and the total level of impurities in the filtered solution filled into the injection device of the parenteral dosage form at the initial time and during storage at various time points at room temperature (25°C/60% relative humidity) and at a temperature of 2 to 8°C were determined using the high performance liquid chromatography method described above.

It was found that after 6 months of storage at room temperature, the level of impurities A, B, single maximum of unknown impurity and total impurity level did not change or the change was insignificant. Based on these data, it is expected that the parenteral dosage form of the present invention is chemically stable over a long period of time. It was found that the solutions do not show any problems with regard to agglomeration or increase in viscosity during preparation, and when filling the injection device, and during storage. The data also demonstrated that there was no absorption or adsorption of cetrorelix on or in the components of the device, such as the rubber stroke limiter, which was in contact with the solution during the storage period.

Results of a stability study for a stable parenteral dosage form

- 12 048164 administrations at 25°C/60% RH and 2-8°C in accordance with the present invention are presented in Tables 4 and 5.

Table 4

Observation at various time points during storage at (254.760% RH) pH Impurity L (%) Impurity B (%) One f i o n m a x i m u m of unknown impurity (%) Total impurity level (%) Moments of time (months) 0 1 J 6 0 1 3 6 0 1 3 6 0 1 3 6 J BQL (1.20 0.54 1,0 0,055 ND ND BQL 0.113 0.123 0.112 0.431 0.363 0.398 0.748 1.829 3.5 BQL 0.07 0.23 0,40 0.068 ND BQL BQL 0,105 0.148 0,189 0.392 0.335 0.292 0.623 1.059 4 BQL BQ I. 0.09 0.15 0.039 ND ND ND 0.095 0.162 0.196 0.388 0.308 0.302 0.496 0,792 4,5 ND BQL BQL 0,04 0,058 ND ND ND BQL 0.159 0.204 0.331 0.308 0.237 0.331 0.563 5 BQL BQL ND BQL - 0.119 0.125 0.205 0.208

ND: not detected;

RH - relative humidity;

BOL: below the limit of quantification.

Table 5

Na.day at different times during storage at (2-8 C) pH Impurity L (%) Impurity B f%) “ΧΖ'α» impurityG)''”'' ⁰⁶ '< ^% > Momeshy in times (months) 0 1 3 6 ¹² And 0 1 z : 6 12 18 24 0 1 3 6 12 18 24 0 1 3 6 12 18 24 3 BQL 0.05 0.08 0.18 0.363 1.545 0.055 ND ND ND BQL BQL BQL 0,113 0.079 0,08 Yu.146 0.109 0,138 0,15 0.363 0.206 0,161 0.333 0.551 0.628 0,695 3.5 BQL BQL BQL 0,06 0,144 ),238 0,068 BQL ND ND BQL BQL BQL 0,105 0,087 0,069 0,135 0.108 0,139 0,149 0.335 0,087 0.069 0.197 0.337 0.31 0.387 4 BQL BQL BQL 0,03 0.055 ).078 0,039 ND ND ND ND ND BQL 0,095 0.16 0.144 0.138 0.105 0.186 0,15 0.308 0.23 0.144 0.174 0.242 0.398 0.228 4,5 ND BQL ND BQ1 BQL. }QI 0.058 ND ND ND ND BQL. ND BQL 0,142 0.136 0.136 0,107 0.134 0,15 0.308 0.213 0.136 0.136 0.193 0.202 0.15

MD: not found;

RH - relative humidity;

BQL: below the limit of quantification.

Stability study results for additional intermediate pH ranges were studied at various time points during storage at 25°C/60% RH and 2-8°C and are presented in Table 7.

Table 6

Cetrorelix acetate content, eq. cetrorelix (%) Storage conditions |2-8°С 25°С/60% RH pH Unfiltered Initial value 1M 2M zm 6M 12 M 18 M 24 M 1M 2M ZM 6M 2,5 104.05 103.97 103.03 105.51 105.04 104.54 103.7 - 102.76 102.9 102.9 99.97 3 103.56 101,11 101.8 104.9 105.42 104 103.5 104.93 104.77 102.09 104.71 105.08 102.36 3.5 103.86 102.51 101.82 104.88 102.88 104.2 103.1 104.13 104.16 103.65 103.62 102.23 103.68 4 103.76 102.96 104 104.17 104.75 104.84 103.3 104.48 103.61 102.58 103.28 103.72 103.39 4,5 102.52 99.56 103.43 103.97 103.57 103.59 102.6 103.97 103.86 101.66 103.62 102.79 102.77 5 99.48 - - 99.02 - -

Table 7 |No..B{%)

[12 M |1 m

OT! OT! OT! OT!

from:

0.24 0.25 324

0.29 0.29 3.24

0.18 0.18 3.18

ΙΚΒΪ3ΙΗ

ΙΉϊΙΐ^Π^ΐΐϊΙ I liTITEWTEWTi"! isazisas!! 12"12I2I2y· 1351531 |3ΐ"17Ε13^ΐϊϊ1

Three.......

ND bqlbqL mTKdE |nd~nd

ND ND ND~ND ND ND

Β·ΙΒ jSB2j21S3:

ziyaniizz:

II in

II III

EL..1ND......ί......E.................1 ....................E.

BQL BQL BQL-______-___

BQL BQL BQL-___;___-___

BQ1 BQl.BQi.-___- :____

PQL BQL BQL-_________

BQL BQL BQL BQL BQL BQL SQL BQL BQL ND ND ND.....

BQLBQLBQLNDNDND

Bm Ιϊμ 5Ίμ EymG

0.8651),8730.861 0.934

0.906 0.896 0.8921.03^

0.7 [],7 0.586 (L72~j ),6670.6560.66 0.6781

0.3650.46 0.3730.294

0.5043.581 0.501 0.379|

0.414 3.4150.415 0 294]

1Ϊ2 Μ

In III

ND: not detected;

RH - relative humidity;

BQL: below quantification limit; NA: not available.

- 13 048164

Table 8

Cetrorelix acetate content, eq. cetrorelix (%) Storage conditions 2-8°С 25°С/60% RH rn Unfiltered Initial value 1 M 3 M 6M 12M 1 m 3 m 6M 3.1 99.96 98.67 99.12 99.32 98,98 98.94 98.65 97.65 97.52 3.2 100.89 100.21 99.9 100.89 99.61 101.27 100.06 100.38 98.2 3,3 99.96 99.05 98.58 100,03 99.13 100.29 98,97 99.87 98.13 3,4 100,02 98.54 99.59 - - 99.91 99.97 99.03

Table 9

Stability data for cetrorelix acetate injection

0.25 mg/ml, 1 ml PFS at pH 5

Each ml contains cetrorelix acetate, equivalent to 0.25 mg cetrorelix, 54.8 mg mannitol, lactic acid in an amount sufficient to adjust the pH to 5.0, water for injection in an amount sufficient to bring to 1 ml.

Description Cetrorelix acetate content, eq. cetrorelix Related substances Known impurities Unknown impurities Total impurity level Impurity A Impurity B Highest level of unknown impurity 95.0%-105.0% according to LC No more than 1.0% No more than 1.0% No more than 0.5% No more than 3.5% UNFILTERED BATH y 99.59 INITIAL VALUE y 99.67 BQL (<0.03 5%) ND 0,131 0,131 2-8°С OTS 1M y 98.13 BQL (<0.03 5%) ND 0.11 0,182 2M y 98.6 ND ND 0.109 0.208 zm y 99.98 ND ND 0,112 0,198 25°С /60% RH OTS 1M y 98 BQL (<0.03 5%) ND 0.106 0.106 2M y 98.24 0,074 ND 0.109 0.369 ZM y 98.18 0.18 ND 0,107 0.353

ND: not detected;

RH - relative humidity;

BQL: below quantification limit;

*A clear, colourless solution that fills a 1 ml reservoir of PFS.

Comparative example 1.

Moment 1 Observation at different times during storage time pH [Impurity Λ (%)

Table 10

[Impurity B (¾)

0 M I m |z M HI 12 M [Ohm I M 3 M 6M 12 M 1 no [ ¹¹ pyal |п |ιιι I II HI I II ш [I |п HI [ II III i II 111 I II 111 I 11 HI at (25T 60% RH) 2.5 oh.oh I ).82 3.38 2EE - BQL 0.23 . 0.36 2.6 0.08 I Sh)8 1.28 1.29 ίΕΕΙΐΕΐ Y and y ga SHI ND ND ND p.23 0.21 125 2.7 0.58 Ь.58 ).99 1.00 ZEEVE 1.85 1.84 1.86 . \D ND \L) 0.21 018 BQL 0.18 0.22 119 2.X 0.06 3GH ko? 180 0.81 DD1CC) ΪΕΕ 1.56 1.56 1.56 SE1 . Nd ND ND BQL 0.183 BQL BQL BQL BQL 2.9 0,06 h k()5 ).67 0.66 EVERYWHERE IC 1.30 1.32 1.30 for . ND ND ND BQL BQL BQL 0.204 0.204 1194 At 2-84.’ 2.5 0,08 I 120 YALE F Ь.бз 1.33 AND . BQL . (3QL BQL . BQL 2.6 0,08 ZEZ k()8 ).72 0.73 yade y kya EYA kYA IM yes . ND ND ND BQL 133 P ^QL - 2.7 0.58 EЁ0 1.58 0.58 ND Sh13E1 M kbo 0.6 0.59 for . ND ND ND BQL BQL BQL BQL BQL 2.K 0.06 ZEN Ь.07 0.48 0.49 ZSZZ LE 0.46 0.45 0.46 77D . ND ND ND BQL PQL BQL BQL BQL 2.9 0,06 p.05 ).42 0.42 | |0.39 0.39 0,40 For ND ND ND BQL PQL BQL BQL BQL

[General >

time

Moments Observation at different times during storage pH [Single maximum non-weston impurity (%)}

Moments of time (months)

i) m

At (25 ^C C

60°« RH)

At 2-8’C for:

I.

for:

I

K105

II HI

M hi Ιιί

).159-_____Ьм

0.138 0.125[Ы21рЛ550.1540.15 0.141 0.153 0.141k 145 [).148 0.18 0.14 D, 133 ίΰ 451),173 0.124 0.13:

0.142 1131 ϊ 14 k 137 0.132 J, 13'

1F!

BARELY!

).105 ),1731138 0.125 11200407 112211L ),141 0.1531141kl 160.109111

).14 OLZZOYZHGG 1135113:

)J 42 RL 31PJ 4 p i 2φ· ί 24kiT

I3EJ! γϊικι: oil:

and

6M m

M DM

In___ HI 1 11 III I I III I II III I II III 0.417 0.409 1.067 p. 199 1201 . 0.227 1214 121 1.708 1.69 1.721 jo.237 1245 0.191 0,2 1194 0.3x1 1393 1311 1,365 1.344 1.46 b.218 0.247 i»,21 0.166 1165 0.277 0.209 0.299 1,214 1,162 1.149 p.222 0.223 0.19 0.159 1167 -: 0.272 [),283 1195 0.939 1919 1.048 0.139 , 0.11- 0.409 . 0.43 ki4 0.142 - 0.227 1214 0.21 0.923 1,022 0.93 to 146 1191 0.126 0,132 1113 0.381 1393 3.311 0,863 0,866 0,78fj kl4 1125 1124 0,111 111 0.277 0.209 0.299 0.679 0.731 0.731 10.126 0,147 0.112 0.135 1123 - 0.272 ).283 0.195 0.673 [),664 0,6361

]z\G m

M

|n___ HI I 11 HI 1 II III 4,404 p.789 2.896 - p.269 2.092 2.424 2.486 2.423 1,909 1.831 2,032 2.011 1.914 - * 1.459 1,457 1,902 1.788 1,799 0.842 - 1,521 [1,374 1.383 1.188 i .3'3 0.798 1731 0,779 - 1,121 0.991 0.655 ).646 0,725 » - 10.884 0,87g 0.505 1525 0.526 -

ND: not detected;

RH - relative humidity;

BQL: below quantification limit;

NA: Not available.

- 14 048164

Table 11

Cetrorelix acetate content, eq. cetrorelix (%) Storage conditions Initial shaking 2-8°С 254760% RH pH Unformulated 1 m 3 6 M 1 m ZM 6.M 1 II III I AND HI 1 II III I II III I n Ill I II HI I 11 III 2.6 100,05 100.25 100,04 99.63 98.65 98.32 99.27 98.27 98.22 97.45 97 97.76 97.2 1 96.58 96.25 96.63 2.7 100.75 100.4 100.66 98.69 99.22 98.78 98.94 98.74 99.77 99.87 97.82 99 98.36 98.22 98.55 97.4 98,04 97.55 96,97 97,07 97.09 2.8 100.7 100.93 100.99 99.39 98.76 99.05 98.69 99.33 98.57 99.85 100.18 99.92 97.64 97.62 97.65 97.74 97.65 97.94 98,12 96.51 96.04 2.9 - 97.55 97.6 97.68 98.64 98.62 98.47 95.37 95.42 95.55 97.75 97.8 98.52 96.92 96.84 96.56 95.19 94.8 94.8 94.23 94.32 95.26

Comparative example 2.

An aqueous solution of cetrorelix acetate was prepared according to the disclosure of US 2013/0303464 (Patel et al.). The composition is shown in Table 12.

Table 12

Ingredients Quantity (mg/ml) Cetrorelix acetate 0.25 Mannitol 42,0 Glacial acetic acid Sufficient amount to obtain a pH of 3.0 Water for injection 1 ml

Method of preparation: water for injection was taken at a temperature of 2 to 8 °C in a vessel. Mannitol was added and gradually dissolved in water for injection with stirring until a clear solution was obtained. Cetrorelix acetate was added to the resulting solution and gradually dissolved with stirring. Then glacial acetic acid was added and the pH of the solution was adjusted to approximately 3.0. The volume was brought to the mark with water for injection. The solution was stirred for 10-15 minutes and then aseptically filtered through a layer of membrane filter with a pore size of 0.2 μm (optiscale 47 capsule, polyethersulfone membrane filter from Millipore). The solution was aseptically filled into the reservoir of the injection device, i.e. the barrel of a 1 ml glass syringe with a filling volume of 1.1 ml. The pre-attached needle in the barrel was sealed with an elastomeric needle cap, which was closed with a rigid cap before filling. After filling, the glass syringe (barrel) was sealed with a piston stroke stopper using a vacuum stopper such that essentially no free air space remained inside the syringe. The aqueous solution during storage remains in contact with the piston stroke stopper made of rubber, the pre-attached needle made of stainless steel, and the needle cap made of natural rubber.

The solution of this comparative example (Comparative Example 2), which was filled into a glass syringe, was subjected to a storage stability test.

The level of impurity A, impurity B and total impurity in the solution were analyzed at the initial time and after storage at room temperature (25°C/60% relative humidity) using the high-performance liquid chromatography method. The results are shown in Table 13.

Table 13

Results of the stability study for comparative example 2

Impurity A (%) (25°C/60% RH) Impurity B (%) (25°C/60% RH) Total impurity level (%) (25°C/60% RH) Moment in time (Months) 0 3 6 0 3 6 0 3 6 0,06 0.84 1.77 ND 0,07 0.17 0.99 1.88 2.83

ND: not detected;

RH: relative humidity.

It was observed that the cetrorelix acetate solution from US 2013/0303464 (comparative example) showed a significant increase in the level of impurity A and the total impurity level when stored at room temperature. In particular, the level of impurity A, which is an impurity formed as a result of degradation, increased significantly and increased to 1.77% by weight of cetrorelix after 6 months. Also, the total impurity level increased to 2.83% by weight of cetrorelix after 6 months.

In contrast, the parenteral dosage form containing the ready-to-inject aqueous solution of cetrorelix acetate according to the present invention remains stable at room temperature for an extended period of time, with virtually no degradation or increase in impurity A, other impurities or total impurity levels occurring during storage, and the extrapolated shelf life of the solution is more than 24 months.

Claims (12)

1. A dosage form for parenteral administration containing a ready-to-inject stable aqueous solution containing: (i) cetrorelix in an amount of 0.25 mg/ml or a pharmaceutically acceptable salt thereof; (ii) lactic acid at a concentration to maintain the pH in the range of 4.00 to 5.00; (iii) impurity A, which is a decapeptide of formula I, in an amount of less than 1% w/v of the cetrorelix base: Formula I, (iv) osmotic agent and (v) water for injection. 2. A dosage form for parenteral administration according to claim 1, wherein the osmotic agent is present in an amount sufficient to provide an osmolarity of the solution in the range from 250 to 375 mOsm/kg. 3. A dosage form for parenteral administration according to claim 1, wherein a ready-to-inject stable aqueous solution is present in the reservoir of the injection device. 4. A dosage form for parenteral administration according to claim 3, wherein the injection device is an autoinjector or a pre-filled syringe. 5. A dosage form for parenteral administration according to claim 3, wherein the injection device is an autoinjector in the form of a pen. 6. A parenteral dosage form according to claim 1, wherein the parenteral dosage form is suitable for subcutaneous administration. 7. A parenteral dosage form according to claim 1, wherein the parenteral dosage form is suitable for intramuscular use. 8. A method for suppressing a premature surge of luteinizing hormone in a woman undergoing controlled ovarian stimulation, comprising administering to said woman a parenteral dosage form according to claim 1. 9. Decapeptide of formula I Formula I. 10. The decapeptide of claim 9, wherein the decapeptide is identified by HPLC analysis, and the method comprises: a) introducing a diluent containing water, acetonitrile and formic acid into the chromatographic system, b) introducing a system suitability assessment solution containing cetrorelix acetate, diluent and impurity stock solution and recording the chromatogram, c) introduction of a standard solution containing cetrorelix acetate and diluent into the chromatographic system, d) introducing a sample containing an aqueous solution of cetrorelix acetate and a placebo preparation into the chromatographic system and e) determination of the relative retention time and relative response factor for the impurity and cetrorelix acetate peaks relative to the cetrorelix acetate peak. 11. A method for identifying a decapeptide according to claim 9 using HPLC analysis, the method comprising: a) introduction of a diluent containing water, acetonitrile and formic acid into the chromatograph - 16 048164 Czech system, b) introducing a system suitability assessment solution containing cetrorelix acetate, diluent and impurity stock solution and recording the chromatogram, c) introduction of a standard solution containing cetrorelix acetate and diluent into the chromatographic system, d) introducing a sample containing an aqueous solution of cetrorelix acetate and a placebo preparation into the chromatographic system and e) determination of the relative retention time and relative response factor for the impurity and cetrorelix acetate peaks relative to the cetrorelix acetate peak. 12. The method according to claim 10 or 11, wherein the mobile phase A and B in the HPLC analysis comprises a buffer, acetonitrile and tetrahydrofuran, and wherein the determined relative retention time and relative response factor for the decapeptide peak are 0.57 and 1.0, respectively.