Description:
FIELD OF THE INVENTION

The present invention relates to an improved process for the preparation of Rocuronium Bromide.

The invention further relates to an improved process for the preparation of Rocuronium Bromide free of residual solvents as well as diacetyl impurity and des-pyrrolidine keto impurity as well as other impurities.

Diacetyl Impurity Des- pyrrolidine keto Impurity

BACKGROUND OF THE INVENTION

Rocuronium Bromide is a non-depolarizing neuromuscular blocking agent with a rapid to intermediate onset depending on dose and intermediate duration and is indicated for inpatients and outpatients as an adjunct to general anesthesia to facilitate both rapid sequence and routine tracheal intubation, and to provide skeletal muscle relaxation during surgery or mechanical ventilation.

It is chemically known as 1-[17ß-(acetyloxy)-3a-hydroxy-2ß-(4-morpholinyl)-5a-androstan-16ß-yl]-1-(2-propenyl)pyrrolidinium Bromide and is represented by Formula I.

Formula I
Rocuronium Bromide and related compounds are described in US 4894369 A (hereinafter referred as US’369). US’369 discloses process of preparation of Rocuronium Bromide as represented in Scheme-I below:

Scheme-I
US’369 describes the physical and chemical characteristics of Rocuronium bromide, but does not detail the identity and quantity of the impurities, the chemical stability, solid state stability, and “shelf life” of the product. Moreover, patent U.S. Pat. No. 4,894,369 does not disclose whether it is possible to provide Rocuronium Bromide as a stable, pure solid. Furthermore, no information is provided in relation to how this compound may be obtained in such a form. It was found that following the process given in US’369 results in compound with significant amount of impurity. The reason is the significant increase in the amounts of impurities in the product, which was probably caused by carry over impurity from previous steps also, attempts to remove the residual organic solvents to the desired level by performing more drastic techniques known in the art, such as drying under high vacuum at elevated temperatures for extended periods of time, also failed. The reason is the significant increase in the amounts of impurities in the product, which was probably caused by degradation.

US 8242265 B2 discloses process of purification of Rocuronium Bromide in which Rocuronium Bromide is first dissolved in carbonated aqueous solution and then freeze dried. US’265 does not talk about impurity level of final freeze dried product and is focused only on elimination of residual solvents.

US 2006/0058275 describes buffering the aqueous solution to prevent the formation of a basic pH. Sodium acetate is used as preferred buffer. However, when the buffered solution is freeze dried, the resulting solid contains unacceptable amounts of buffer. US’275 also discloses use of water and acetic acid for the lyophilization of final compound, however use of acetic acid is not advisable which results in formation of Allyl Acetate impurity which is genotoxic.

CN 103435674 B discloses a preparation method of Rocuronium Bromide, which comprises the following steps: dissolving crude Rocuronium Bromide in DCM, adding alumina, stirring vigorously for 2-4 h, filtering with filter paper and an organic filter membrane respectively, and dropwise adding the obtained filtrate into vigorously stirred diethyl ether to separate out a large amount of white solid; and dissolving the white solid in a dilute acetic acid solution, wherein the pH value of the dilute acetic acid solution is 3-5, quickly freezing the solution into ice, and then freeze-drying. However, the content of acetic acid in the Rocuronium Bromide pure product obtained by the scheme is about 20 wt%, and the Rocuronium Bromide pure product does not meet the USP pharmacopoeia standard. In CN’674 too much acetic acid is added for keeping Rocuronium Bromide in water stable, the filtrate needs to be added into vigorously stirred diethyl ether, and when industrial production is carried out, a large amount of diethyl ether needs to be used, using excess amount of diethyl ether have serious potential safety hazard.
CN 113368115 B discloses use of acetic acid and water in lyophilization process. However, use of acetic acid is not advisable as use of acetic acid invokes the formation of Allyl Acetate impurity which is genotoxic. CN 113368115 B does not describe any further purification to decrease the impurity in final compound.

The present invention overcomes the problems and difficulties associated with prior art process and provides a commercially viable process for the production of pure Rocuronium Bromide with pharmaceutically acceptable level of impurities as well as free of residual solvents.

OBJECT OF THE INVENTION

Main object of the present invention is to provide an improved process for the preparation of Rocuronium Bromide.

Another object of the present invention is to provide an improved process for the preparation of Rocuronium Bromide free of residual solvents as well as diacetyl impurity and des-pyrrolidine keto impurity as well as other impurities.

Diacetyl Impurity Des- pyrrolidine keto Impurity

In another object the present invention provides an improved process for the preparation of Rocuronium Bromide of Formula I,

Formula I
comprising the steps of:
a) acetylating (2ß,3a,5a,16ß,17ß)-2-(4-morpholinyl)-16-(1-pyrrolidinyl)androstane-3,17-diol of Formula II to give (2ß,3a, 5a,16ß,17ß)-2-(4-morpholinyl)-16-(1-pyrrolidinyl)-androstane-3,17-diol-17-acetate of Formula III,

Formula II Formula III
b) reacting compound of Formula III with allyl bromide to give Rocuronium Bromide; and
c) treating crude Rocuronium Bromide obtained in step b) with hydrobromic acid followed by lyophilization to give pure Rocuronium Bromide.

In another object the present invention provides an improved process for the preparation of Rocuronium Bromide of Formula I free of residual solvents; diacetyl impurity; des-pyrrolidine keto impurity as well as other impurities

Formula I
Comprising the steps of:
a) reacting compound of Formula III with allyl bromide to give crude Rocuronium Bromide,
b) treating the crude Rocuronium bromide with suitable acid followed by suitable base in presence of suitable solvent; and
c) lyophilizing Rocuronium Bromide obtained in step b).

SUMMARY OF THE INVENTION

In one aspect the present invention provides an improved process for the preparation of Rocuronium Bromide of Formula I,

Formula I
comprising the steps of:
a) acetylating (2ß,3a,5a,16ß,17ß)-2-(4-morpholinyl)-16-(1-pyrrolidinyl) androstane-3,17-diol of Formula II to give (2ß,3a, 5a,16ß,17ß)-2-(4-morpholinyl)-16-(1-pyrrolidinyl)-androstane-3,17-diol-17-acetate of Formula III,

Formula II Formula III
b) reacting compound of Formula III with allyl bromide to give Rocuronium Bromide; and
c) treating crude Rocuronium Bromide obtained in step b) with hydrobromic acid followed by lyophilization to give pure Rocuronium Bromide.

In one aspect the present invention provides an improved process for the preparation of Rocuronium Bromide of Formula I free of residual solvents; diacetyl impurity; des-pyrrolidine keto impurity as well as other impurities,

Formula I
comprising the steps of:
a) reacting compound of Formula III with allyl bromide to give crude Rocuronium Bromide,
b) treating the crude Rocuronium bromide with suitable acid followed by suitable base in presence of suitable solvent; and
c) lyophilizing Rocuronium Bromide obtained in step b).

Another aspect of the present invention is to provide a stable pharmaceutical composition of Rocuronium Bromide having less amount of impurities and residual solvents.

DETAILED DESCRIPTION
The present invention will now be explained in details. While the invention is susceptible to various modifications and alternative forms, specific embodiment thereof will be described in detail below. It should be understood, however that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternative falling within the scope of the invention as defined by the appended claims.

The steps of a method may be providing more details that are pertinent to understanding the embodiments of the present invention and so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

Further characteristics and advantages of the process according to the invention will result from the description herein below of preferred exemplary embodiments, which are given as indicative and non-limiting examples.

In one embodiment of the present invention provides an improved process for the preparation of Rocuronium Bromide of Formula I,

Formula I
comprising the steps of:
a) acetylating (2ß,3a,5a,16ß,17ß)-2-(4-morpholinyl)-16-(1-pyrrolidinyl) androstane-3,17-diol of Formula II to give (2ß,3a, 5a,16ß,17ß)-2-(4-morpholinyl)-16-(1-pyrrolidinyl)-androstane-3,17-diol-17-acetate of Formula III,

Formula II Formula III
b) reacting compound of Formula III with allyl bromide to give Rocuronium Bromide; and
c) treating crude Rocuronium Bromide obtained in step b) with hydrobromic acid / ascorbic acid followed by lyophilization to give pure Rocuronium Bromide.
In one embodiment, solvent used for acetylating the compound of Formula II is selected from polar aprotic solvents such as dimethyl formamide (DMF), dimethyl acetamide (DMAc), N-methyl pyrrolidinone (NMP), and dimethyl sulfoxide (DMSO); halogenated solvents such as dichloromethane (DCM), dichlorobenzene, dichloroethane; esters such as ethyl acetate (EtOAc), n-butyl acetate, isopropyl acetate, n-propyl acetate, propenyl acetate, pentyl acetate; ethers such as diethyl ether, tetrahydrofuran (THF), dioxane, methyl tetrahydrofuran (Me-THF); ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone; organic amines such as secondary and tertiary amines; other solvents such as acetonitrile, xylene, toluene water; and mixture thereof.

In another embodiment, acetylation of the compound of Formula II in step a) is carried out by using acetic anhydride in presence of base selected from inorganic base such as sodium hydroxide, potassium hydroxide, cesium hydroxide, lithium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, cesium carbonate, cesium bicarbonate or organic base such as trimethylamine, dimethylamine, ammonia, pyridine or mixture thereof. In preferable embodiment base used is trimethylamine.

In another embodiment acetylated compound of Formula III is purified by recrystallization of crude compound obtained in step a) with solvent selected from polar solvents such as methanol, ethanol, n-propanol, isopropanol, glycol; polar aprotic solvents such as dimethyl formamide (DMF), dimethyl acetamide (DMAc), N-methyl pyrrolidinone (NMP), and dimethyl sulfoxide (DMSO); halogenated solvents such as dichloromethane (DCM), dichlorobenzene, dichloroethane; esters such as ethyl acetate (EtOAc), n-butyl acetate, isopropyl acetate, n-propyl acetate, propenyl acetate, pentyl acetate; ethers such as diethyl ether, tetrahydrofuran (THF), dioxane, methyl tetrahydrofuran (Me-THF); ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone; organic amines such as secondary and tertiary amines; other solvents such as acetonitrile, xylene, toluene water; and mixture thereof. Preferred solvent used for crystallization is acetonitrile.

In an embodiment, allylation of compound of Formula II in step b) is carried out in presence of solvent selected from polar solvents such as methanol, ethanol, n-propanol, isopropanol, ethylene glycol; polar aprotic solvents such as dimethyl formamide (DMF), dimethyl acetamide (DMAc), N-methyl pyrrolidinone (NMP), and dimethyl sulfoxide (DMSO); halogenated solvents such as dichloromethane (DCM), dichlorobenzene, dichloroethane; esters such as ethyl acetate (EtOAc), n-butyl acetate, isopropyl acetate, n-propyl acetate, propenyl acetate, pentyl acetate; ethers such as diethyl ether, tetrahydrofuran (THF), dioxane, methyl tetrahydrofuran (Me-THF); ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone; organic amines such as secondary and tertiary amines; other solvents such as acetonitrile, xylene, toluene water; and mixture thereof.

In an embodiment, Hydrobromic acid (HBr/Hydrogen Bromide) or ascorbic acid used in step c) helps in stabilizing the Rocuronium Bromide. Addition of HBr/ascorbic acid to Rocuronium Bromide helps in stabilizing the molecule and also decreasing degradation impurities as well as genotoxic impurities during lyophilization. Hence it is advantageous to use HBr/ascorbic acid when compared to acetic acid. Use of acetic acid invokes the formation of allyl acetate impurity which is genotoxic and limit is equivalent to allyl bromide itself. Use of HBr / ascorbic acid avoids the formation of allyl acetate impurity and also molecule is stable under lyophilization conditions. Further the possibility of counter-ion interactions between bromide and acetate is also diminished. Hence, use of HBr / ascorbic acid in place of acetic acid is far better than acetic acid to stabilize the molecule and increasing the purity level.

In another embodiment present invention provides a novel process for the lyophilization of Rocuronium Bromide comprising steps of:
a) dissolving Rocuronium Bromide in carbonated water,
b) adding hydrobromic acid or ascorbic acid to solution of step a; and
c) lyophilizing the solution of step b).

In another embodiment carbonated water as used in step a) is prepared by purging carbon dioxide in water to achieve pH 6.0-8.0 of aqueous solution at temperature 2-5oC.

In another embodiment addition of hydrobromic acid at step b) is done either dissolving hydrogen bromide directly into the aqueous solution containing Rocuronium Bromide or adding aquous solution of hydrogen bromide to a solution containing Rocuronium Bromide.

In another embodiment lyophilization at step c) is carried out at temperature as low as – 40oC.

In another embodiment of the present invention provides an improved process for the preparation of Rocuronium Bromide of Formula I free of residual solvents; diacetyl impurity; des-pyrrolidine keto impurity as well as other impurities,

Formula I
comprising the steps of:
a) reacting compound of Formula III with allyl bromide to give crude Rocuronium Bromide,
b) treating the crude Rocuronium bromide with suitable acid followed by suitable base in presence of suitable solvent; and
c) lyophilizing Rocuronium Bromide obtained in step b).

In an embodiment allylation of Step a) is performed by treating compound III with allyl bromide in present of solvent.
In an embodiment, solvent used in step a) is selected from polar solvents such as methanol, ethanol, n-propanol, isopropanol, ethylene glycol; polar aprotic solvents such as dimethyl formamide (DMF), dimethyl acetamide (DMAc), N-methyl pyrrolidinone (NMP), and dimethyl sulfoxide (DMSO); halogenated solvents such as dichloromethane (DCM), dichlorobenzene, dichloroethane; esters such as ethyl acetate (EtOAc), n-butyl acetate, isopropyl acetate, n-propyl acetate, propenyl acetate, pentyl acetate; ethers such as diethyl ether, tetrahydrofuran (THF), dioxane, methyl tetrahydrofuran (Me-THF); ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone; organic amines such as secondary and tertiary amines; other solvents such as acetonitrile, xylene, toluene water; and mixture thereof.

Suitable acid used in step b) is selected from inorganic acid selected from Hydrobromic acid, Hydrochloric acid (HCl), Sulphuric acid. Organic acids include multivalent organic acids, in particular citric acid, phosphoric acid, oxalic acid, succinic acid, tartaric acid, aspartic acid, ascorbic acid, maleic acid, acetic acid, benzoic acid, phthalic acid, mandelic acid and fumaric acid.

Suitable base used in step b) is selected from inorganic or organic base. Inorganic base may be selected from but not limited to sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, potassium tert. butoxide, potassium acetate, sodium acetate, cesium carbonate, potassium hydroxide, sodium hydroxide, calcium hydroxide, magnesium hydroxide, lithium hydroxide, ammonium hydroxide, sodium methoxide, potassium methoxide, and the like. Organic base may be selected from but not limited to pyridine, dimethyl amine, triethyl amine, ?,?-diisopropylethyl amine, N-methyl morpholine, ?,?-dimethyl piperazine, N-methyl piperidine. Prefered base used in present invention is sodium bicarbonate, sodium carbonate or sodium carbonate.

Suitable solvent used in step b) is selected from dimethyl formamide (DMF), dimethyl acetamide (DMAc), N-methyl pyrrolidinone (NMP), and dimethyl sulfoxide (DMSO); halogenated solvents such as dichloromethane (DCM), dichlorobenzene, dichloroethane; esters such as ethyl acetate (EtOAc), n-butyl acetate, isopropyl acetate, n-propyl acetate, propenyl acetate, pentyl acetate; ethers such as diethyl ether, tetrahydrofuran (THF), dioxane, methyl tetrahydrofuran (Me-THF); ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone; organic amines such as secondary and tertiary amines; other solvents such as acetonitrile, xylene, toluene water; and mixture thereof.

In step c) lyophilization is carried out by any process disclosed in prior art.

In another embodiment process as described in present invention may proceed without the isolation of intermediate compounds.

In further embodiment, the Rocuronium Bromide of Formula I obtained by the process of the present invention is optionally crystallized in organic solvent.

In another embodiment organic solvent used for crystallization of compound of Formula I is selected from polar aprotic solvents such as dimethyl formamide (DMF), dimethyl acetamide (DMAc), N-methyl pyrrolidinone (NMP), and dimethyl sulfoxide (DMSO); halogenated solvents such as dichloromethane (DCM), dichloroethane; esters such as ethyl acetate (EtOAc), n-butyl acetate, isopropyl acetate, n-propyl acetate, propenyl acetate, pentyl acetate; ethers such as diethyl ether, tetrahydrofuran (THF), dioxane, methyl tetrahydrofuran (Me-THF); MTBE; DIPE; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone; organic amines such as secondary and tertiary amines; other solvents such as acetonitrile, xylene, cyclohexane, hexane, heptane, toluene water; and mixture thereof.

In further embodiment, the present invention further provides a composition comprising Rocuronium Bromide of Formula I obtained by the process of the present invention along with at least one pharmaceutically acceptable excipients thereof.

In further embodiment, the present invention provides a solid comprising Rocuronium Bromide with purity more than 98% and preferably more than 99.5%.

In another embodiment, Rocuronium Bromide as prepared by the process of the present invention is characterized by particle size distribution wherein, d90 is 0.1µm to 200µm.

In a preferred embodiment, Rocuronium Bromide as prepared by the process of the present invention is characterized by particle size distribution wherein, d90 is 2.0 µm to 150µm.

In a preferred embodiment, Rocuronium Bromide prepared by the process of the present invention results in amorphous Form.

The present invention is explained below by way of examples. However, the examples are provided as one of the possible way to practice the invention and should not be considered as limitation of the scope of the invention.

EXAMPLES:
Example 1: Preparation of (2ß,3a, 5a,16ß,17ß)-2-(4morpholinyl)-16-(1-pyrrolidinyl)androstane-3,17-diol-17-acetate
(2ß,3a,5a,16ß,17ß)-2-(4-morpholinyl)-16-(1-pyrrolidinyl)androstane-3,17-diol (10.0 g) in dichloromethane (100 ml) was added triethylamine (11.38 g) followed by addition of acetic anhydride in dichloromethane (3.43 g in 20 ml) at 20-25°C. Stirred for 15-20 hrs. After reaction, mass was washed with DM water, stirred, settled and separated the layers. The resulting mixture was concentrated under vacuum to get crude material which was crystallised in acetonitrile to get pure material. Yield (8.0 g).

Example 2: Preparation of Rocuronium Bromide
(2ß,3a, 5a,16ß,17ß)-2-(4morpholinyl)-16-(1-pyrrolidinyl)androstane-3,17-diol-17-acetate (10 g), dichloromethane (10 mL) was added to round bottom flask at 25-30ºC. Allyl bromide (3.71 g) and DM water (1.1 mL) was added to above reaction mass at 20-25°C. Stirred for 12-14 hours at 20-25°C. The solvent was removed under vacuum and residue was dissolved in dichloromethane (50 ml) at 20-25°C then washed with 20% Sodium Bromide (20.0mL), stirred, settled and separated layers at 20-25°C. The solvent was removed under vacuum and residue was dissolved in dichloromethane (60 ml) and added activated carbon (0.5g) at 20-25°C. The mass was filtered, washed with dichloromethane (20 mL) and solution was slowly added into methyl tertiary butyl ether (400 ml) at 20-25°C under nitrogen within 1-2 hrs. Mixture was stirred for 2-3 hrs at 20-25°C under nitrogen. Solid material was filtered under nitrogen and washed with methyl tertiary butyl ether (10.0 mL) at 20-25°C under nitrogen. Suck dry under vacuum to get wet material.

Example 3: Lyophilisation
Prepared carbonated water by purging carbon dioxide in water at 2-5°C, wet material was dissolved in carbonated DM Water (50 mL). Sufficient CO2 was purged to achieve pH 7.0-7.3 of aqueous solution. Hydrobromic Acid (0.01 g) was added into the aqueous solution (Observed pH: 6.8-7.0). Purged Nitrogen and simultaneously apply Vacuum to degas the mass. The aqueous solution was then lyophilized at -40°C and then dried at not more than 30°C under vacuum till water content is not more than 3.0 %.

Example 3: Preparation of (2ß,3a, 5a,16ß,17ß)-2-(4morpholinyl)-16(1-pyrrolidinyl)-androstane-3,17-diol-17-acetate
To (2ß,3a, 5a,16ß,17ß)-2-(4-morpholinyl)-16-(1-pyrrolidinyl) androstane-3,17-diol (100.0 g) in acetonitrile (1000 ml) were added triethylamine (100.05 g) followed by addition of acetic anhydride (30.25 g in 20 ml) at 80-85°C under nitrogen and stirred at 80-85oC for 5-6 hrs and material was cooled to get crude product. Crude material was crystallised in acetonitrile to get pure product (90.0g). HPLC purity = 99.0%.

Example 4: Preparation of Rocuronium Bromide
Product obtained in example 3 was dissolved in dichloromethane (70 mL) at room temperature and added allyl bromide (30.01 g) then added DM water (5 mL) at 10-20°C.Stired for 20-24 hours at 10-20oC.After the reaction is completed dichloromethane (100 ml) was added and reaction mass was cooled to 0-10oC.Water (200ml) was added and pH was adjusted using 5% aqueous hydro bromic acid solution at 10-15oC to settle the layer. Aqueous layer was separated charged in round bottom flask and washed with dichloromethane after washing aqueous layer was charged in round bottom flask and charge dichloromethane (300 ml) at 10-15oC and adjust the pH using sodium bicarbonate (30 g) and raise the temperature up to 10-15oC and the resulting mixture was stirred and layer was separated. Combined layer was washed with 20% sodium bromide solution at 15-20oC solvent was removed and residue was dissolved in dichloromethane. Dichloromethane solution was slowly added in methyl tertiary butyl ether and stir for 30 min at 20-25oC. Solid material was filtered and washed with methyl tertiary butyl ether and suck dried under vacuum to get crude material (100 g).

Example 4: Purification of Crude Rocuronium Bromide
Crude material was charged with demineralized water and pH was adjusted to acedic range using carbon dioxide purging at 10-20oC.Wet material obtained was dissolved in carbonated water at 10-20oC and pH was adjusted to neutral using carbon dioxide purging. Martial was filtered through hyflo and washed with water. After washing filtrate was charged in separately and freeze out at -40oC and lyophilized at -80oC for 48 hrs to get pure material (95.0g). HPLC purity ? 99.8%.

Example 5: Preparation Succinate salt of Rocuronium Bromide
Crude Rocuronium Bromide (10.0 g) was dissolved in 120 ml dichloromethane and succinic acid 1.06 g was added at 10-15°C and stirred for 24.0 hrs or till complete crystallization at 10-15°C product thus obtained was filtered and washed with dichloromethane (10.0 ml). Material was dried under vacuum at 25°C for 4-5 hours (10.68g, 89.5% yield). Chromatographic purity =99.0%. The all unknown impurities were found below 0.05% (By PLC) in the isolated product. Succinate salt of Rocuronium was dissolved in 50 ml dichloromethane and 100.0ml Purified water and cool to 10-15°C. Sodium bicarbonate (8.65g) at 10-15°C was added slowly and temperature was raised to 15-20°C and stirred at 15-20°C for 15-30 minutes to separate the layer. The organic layer was washed with saturated sodium bromide solution (20 ml), stired at 15-20°C for 15-30 minutes and layer was separated. The solvent was removed under vacuum and residue was dissolved in Dichloromethane (80 ml) at 20-25°C. Dichloromethane solution was added slowly into methyl tertiary butyl ether (400 ml) at 20-25°C under nitrogen within 1.0hr and Stirred for 30.0 minute at 20-25°C under nitrogen. Solid was filtered and washed with methyl tertiary butyl ether (50.0 mL) at 20-25°C under nitrogen. Material was suck dried under vacuum to get dried material (10.0g). Chromatographic purity=99.0%.

Analytical Data showing the process results in free of residual solvents; diacetyl impurity; des-pyrrolidine keto impurity as well as other impurities
Residual Solvents:
S. N Batch Number Residual Solvent (ppm)
Acetone Methanol MTBE Dichloromethane Acetonitrile
1. Batch-1 ND ND ND ND ND
2. Batch-2 ND ND ND ND ND

Impurity Profile:
Sr. No Related Substance
(Wt.% by HPLC) Batch-1
Batch-2

Purity 99.94% 99.94%
1. Rocuromium Related compound A ND ND
2. Rocuromium Related compound B ND ND
3. Rocuromium Related compound C 0.06 0.06
4. Rocuromium Related compound D ND ND
5. Rocuromium Related compound F ND ND
6. Rocuromium Related compound G ND ND
7. Rocuromium Related compound H ND ND
9. Rocuromium Related compound E ND ND
10. Diacetyl impurity; ND ND
11. Des-pyrrolidine keto impurity ND ND
* Related compounds/other Impurities as described in specification are given in pharmacopeia/or as given below
Related Compounds Structures:
Related Compounds Related Compounds

Related Compound A

Related Compound G

Related Compound B

Related Compound E

Related Compound C

Related Compound F

Related Compound D Related Compound H

Example 6: Preparation citrate salt of Rocuronium Bromide
Crude Rocuronium Bromide 10.0 g obtained in example 4 was dissolved in 50 ml methanol and added 1.63 g citric acid at 10-15°C. Stirred the resulting mixture at 10-15°C for 24.0 hrs till complete crystallization at 10-15°C. Material was filtered and washed with methanol (10.0 ml) and dried under vacuum at 25°C for 6-8 hours (12.08g, 92.0%d yield) to get the citrate salt. Chromatographic purity =99.0%. The all unknown impurities were found below 0.05% (By HPLC) in the isolated product. Citrate salt 10.0 g thus obtained was dissolved in 50 ml dichloromethane and 100.0 ml Purified water and cool to 10-15°C then slowly added solid sodium bicarbonate (5.45g) at 10-15°C and temperature was raised to 15-20°C and stir at 15-20°C for 15-30 minutes to separate the layer. The organic layer was washed with saturated sodium bromide solution (20 ml) and stirred at 15-20°C for 15-30 minutes and again layers was separated. The solvent was removed under vacuum and residue was dissolved in Dichloromethane (80 ml) at 20-25°C. Dichloromethane solution was slowly added into methyl tertiary butyl ether (400 ml) at 20-25°C under nitrogen within 1.0hr and stirred for 30.0 minute at 20-25°C under nitrogen. Solid as washed with methyl tertiary butyl ether (50.0 mL) and filtered. Obtained solid was suck dried under vacuum to final material (10.0g). Chromatographic purity=99.0%.
Example 7: Preparation citrate salt of Rocuronium Bromide
Crude Rocuronium Bromide 10.0 g was dissolved in 50 ml isopropyl alcohol was added 1.63 g citric acid at 10-15°C and Stirred at 10-15°C till complete crystallization. After Filtration material was washed with isopropyl alcohol (10.0 ml and dried under vacuum at 25°C for 6-8 hours (12.08g, 92.0% yield). Chromatographic purity =99.0%. The all unknown impurities were found below 0.05% (By HPLC) in the isolated product. Citrate salt of Rocuronium was dissolved in 10.0 g of Succinate salt in 50 ml dichloromethane and 100.0ml purified water and cooled to 10-15°C to this was slowly added solid sodium bicarbonate (5.45g) at 10-15°C. Raised temperature to 15-20°C and stir at 15-20°C for 15-30 minutes then layer separated. The organic layer was washed with saturated sodium bromide solution (20 ml), stir at 15-20°C for 15-30 minutes and layer was separated. The solvent was removed under vacuum and residue was dissolved in Dichloromethane (80 ml) at 20-25°C and to this slowly added dichloromethane solution into methyl tertiary butyl ether (400 ml) at 20-25°C under nitrogen within 1.0hrs and Stirred for 30.0 minute at 20-25°C. Solid was filtered and washed with methyl tertiary butyl ether (50.0 mL) at 20-25°C. Suck dried under vacuum to get material (10.0g) material. Chromatographic purity=99.0%.
, Claims:WE CLAIM
1. A process for the preparation of Rocuronium Bromide of Formula I,

Formula I

comprising the steps of:
a) acetylating (2ß,3a, 5a,16ß,17ß)-2-(4-morpholinyl)-16-(1-pyrrolidinyl) androstane-3,17-diol of Formula II to give (2ß,3a, 5a,16ß,17ß)-2-(4-morpholinyl)-16-(1-pyrrolidinyl)-androstane-3,17-diol-17-acetate of Formula III,

Formula II Formula III
b) reacting compound of Formula III with allyl bromide to give Rocuronium Bromide; and
c) treating crude Rocuronium Bromide obtained in step b) with hydrobromic acid or ascorbic acid followed by lyophilization to give pure Rocuronium Bromide.

2. The process as claimed in claim 1, wherein acetylation of compound of Formula II is carried out in presence of solvent selected from polar solvents such as methanol, ethanol, n-propanol, isopropanol, ethylene glyucol, polar aprotic solvents such as dimethyl formamide (DMF), dimethyl acetamide (DMAc), N-methyl pyrrolidinone (NMP), and dimethyl sulfoxide (DMSO); halogenated solvents such as dichloromethane (DCM), dichlorobenzene, dichloroethane; esters such as ethyl acetate (EtOAc), n-butyl acetate, isopropyl acetate, n-propyl acetate, propenyl acetate, pentyl acetate; ethers such as diethyl ether, tetrahydrofuran (THF), dioxane, methyl tetrahydrofuran (Me-THF); ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone; organic amines such as secondary and tertiary amines; other solvents such as acetonitrile, xylene, toluene water; and mixture thereof.

3. The process as claimed in claim 1, wherein acetylation of compound of Formula II is carried out in presence of base selected from trimethylamine, dimethylamine, ammonia, pyridine or mixture thereof.

4. A process for the preparation of Rocuronium Bromide of Formula I free of residual solvents; diacetyl impurity; des-pyrrolidine keto impurity as well as other impurities,

Formula I
comprising the steps of:
a) reacting compound of Formula III with allyl bromide to give crude Rocuronium Bromide,
b) treating the crude Rocuronium bromide with suitable acid followed by suitable base in presence of suitable solvent; and
c) lyophilizing Rocuronium Bromide obtained in step b).

5. The process as claimed in claim 4, wherein acid used in step b) is selected from inorganic acid selected from Hydrobromic acid, Hydrochloric acid or organic acids selected from citric acid, phosphoric acid, oxalic acid, succinic acid, tartaric acid, aspartic acid, hydrochloric acid, maleic acid, acetic acid, benzoic acid, phthalic acid, ascorbic acid, mandelic acid and fumaric acid.

6. The process as claimed in claim 4, wherein base used in step b) is selected from inorganic or organic base. Inorganic base selected from sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, potassium tert. butoxide, potassium acetate, sodium acetate, cesium carbonate, potassium hydroxide, sodium hydroxide, calcium hydroxide, magnesium hydroxide, lithium hydroxide, ammonium hydroxide, sodium methoxide, potassium methoxide, and the like. Organic base selected from pyridine, dimethyl amine, triethyl amine, ?,?-diisopropylethyl amine, N-methyl morpholine, ?,?-dimethyl piperazine, N-methyl piperidine.

7. A process for the lyophilization of Rocuronium Bromide comprising:
a) dissolving Rocuronium Bromide in carbonated water,
b) adding hydrobromic acid or ascorbic acid to solution of step a); and
c) lyophilizing the solution of step b).

8. The process as claimed in claim 6), wherein the lyophilization is carried out at temperature -40oC.

9. Rocuronium Bromide having a purity of greater than 99.9% by HPLC.

Dated 21st day of March, 2023 For Mankind Pharma Ltd.

Dr. Anil Kumar
Chief Scientific Officer