The invention relates to a novel process for purification the pharmaceutical product Sugammadex.

OVERVIEW OF THE PRIOR ART

Sugammadex, i.e. 6A,6B,6C,6D,6E,6F,6G,6H-Octakis-S-(2-earboxyethyl)- 6A,6B,6C,6D,6E,6F,6G-octasulfanyl-gamma-cyelodextrin octasodium salt of formula (1),

is a modified g-cyclodextrin.

Sugammadex is the first selective relaxant binding agent for reversal of neuromuscular blockade by the agent rocuronium or vecuronium in general anesthesia. It was approved in 2008 by EMEA. It is marketed in the form of a sterile solution for intravenous injection under the brand name Bridion®. Sugammadex was first disclosed in WO2001040316. Processes for preparation of sugammadex are disclosed for example in W020001040316, WO2012025937,

W02014125501, W02016194001, WO2017163165 or WO2017144734 applications.

In the prior art processes a compound of formula (2),

is transformed into sugammadex using 3-mercaptopropanoic acid and a sodium base, for example NaH, Na alkoxide or NaOH. The removal of inorganic ions originated in the base from obtained sugammadex is not trivial. Prior art processes advise to use for example dialysis or chromatographic purification. These techniques are not suitable for commercial production.

Sugammadex is marketed in the form of a sterile solution for intravenous injection. It is required to maintain the level of inorganic ions (represented for example by osmolality or sodium content values) on certain levels (for example osmolality value should be between 300 and 500 mOsm/kg according to Bridion® Summary of product characteristics available on webpages of European Medicines Agency).

Therefore, there exists a need for an improved and efficient process for the purification of sugammadex.

BRIEF DESCRIPTION OF THE PRESENT INVENTION The invention provides a process for the preparation of a solid form of sugammadex comprising:

a. Suspending sugammadex in a solvent mixture comprising an aliphatic alcohol, 10-30% (vol%) water and an alkylacetate;

b. Isolating the solid form of sugammadex.

Obtained solid form of sugammadex can be characterized by XRPD pattern having 2Q values 5.5°, 6.0°, 7.6° and 8.5° degrees 2 theta ( ± 0.2 degrees 2 theta). Obtained solid sugammadex can be further characterized by XRPD spectrum depicted in Figure 1. DETAILED DESCRIPTION OF THE PRESENT INVENTION

The invention provides a process for the preparation of a solid form of sugammadex comprising:

a. Suspending sugammadex in a solvent mixture comprising an aliphatic alcohol, 10-30% (vol%) water and an alkylacetate;

b. Isolating the solid form of sugammadex.

The aliphatic alcohol can be for example methanol or ethanol or 1 -propanol or 2- propanol or butanol or 2-butanol or tert-butanol, preferably it is methanol or ethanol, more preferred is methanol.

The alkylacetate can be selected from for example methylacetate or ethylacetate or propylacetate or butylacetate or tert-butylacetate, preferably it is ethylacetate.

The amount of water in the solvent mixture can be between 10 and 30 % (vol%), preferably it is between 20 and 25% (vol%). The amount of water between 10 and 30% (vol%) ensures that sugammadex remains in a solid phase, i.e. the mixture is a suspension.

By use of the presented process inorganic ions can be easily removed from the obtained solid sugammadex. Additionally to that the obtained solid sugammadex is in the form of a crystalline compound that is characterized by XRPD pattern having 2Q values 5.5°, 6.0°, 7.6° and 8.5° degrees 2 theta ( +_0.2 degrees 2 theta). Obtained solid sugammadex can be further characterized by XRPD spectrum depicted in Figure 1.

The amount of the alkylacetate in the solvent mixture can be between 1 and 10 % (vol%), preferably it is between 1 and 5% (vol%), more preferably between 1.1 and 2% (vol%).

There are several possibilities how the suspension in the solvent mixture can be prepared. Sugammadex can be suspended in the aliphatic alcohol. Water and the alkylacetate are subsequently added to the suspension. Altenatively sugammadex can be suspended in a mixture of water and the aliphatic alcohol and the alkylacetate. The suspension can also be prepared by suspending sugammadex in mixture of water and the aliphatic alcohol to which the alkylacetate is subsequently added. The suspension of sugammadex in the solvent mixture can be optionally heated to a temperature between 30°C and the reflux temperature of used solvent mixture, preferably it is heated to a temperature between 45°C and 65°C. The suspension is stirred at this temperature for 0.5 to 10 hours, preferably for 1 to 3 hours.

The suspension is then cooled to a temperature between -l0°C and 30°C, preferably to a temperature between 10 and 25 °C and is stirred at this temperature for between 0.5 and 3 hours.

Obtained sugammadex is isolated by a suitable isolation technique, for example by filtration and is washed with for example an aliphatic alcohol such as methanol or ethanol or propanol. Obtained sugammadex is dried at an elevated temperature for example between 50 and 90°C, preferably between 80 and 88°C.

The obtained sugammadex can be characterized by XRPD pattern having 2Q values 5.5°, 6.0°, 7.6° and 8.5° degrees 2 theta ( ± 0.2 degrees 2 theta). The obtained sugammadex can be further characterized by XRPD pattern having 2Q values 4.6°, 5.5°, 6.0°, 7.6°, 8.5° and 12.7° degrees 2 theta ( ^0.2 degrees 2 theta). The obtained sugammadex can be also characterized by XRPD values given in following table:

The obtained sugammadex can be also characterized by XRPD pattern depicted in

Figure 1. Sugammadex used in the process can be obtained by any method disclosed in the prior art, for example by a method disclosed in W02001040316, WO2012025937,

W02014125501, W02016194001, WO2017163165 or WO2017144734 applications.

In comparison to a purification processes disclosed in the prior art the presented purification process has following advantages:

1. It is suitable for industrial scale;

2. It offers material in API quality with controlled amount of inorganic impurities;

3. The produced material is crystalline solid that allows better drying and prevents formation of agglomerates.

The following examples are intended to illustrate the scope of the present invention but not to limit it thereto.

XRPD patterns were obtained using the following measurement conditions:

Panalytical Empyrean diffractometer with Q/2Q geometry (transmition mode), equipped with a PixCell 3D detector

EXAMPLES Example 1 : Purification of sugammadex

199 g of sugammadex prepared according to a procedure disclosed in example 4 of WO2017144734 application was suspended in 1526 ml of water/methanol (1:4 vohvol) mixture. The suspension was heated to 50°C. 22 ml of ethylacetate was added to the suspension and the suspension was stirred for 60 minutes at 50°C. The suspension was cooled to 25°C and filtered. The filtration cake was washed with 3x300 ml of methanol. Isolated sugammadex was dried at 85°C to yield 175.5 g of sugammadex. XRPD pattern of obtained sugammadex corresponds to XRPD pattern depicted in Figure 1. Example 2: Purification of sugammadex

199 g of sugammadex prepared according to a procedure disclosed in example 4 of WO2017144734 application was suspended in 1221 ml of methanol. 305 ml of water was added to the suspension. The suspension was heated to 50°C. 22 ml of ethylacetate was added to the suspension and the suspension was stirred for 60 minutes at 50°C. The suspension was cooled to 25°C and filtered. The filtration cake was washed with 3x300 ml of methanol. Isolated sugammadex was dried at 85°C to yield 179 g of sugammadex. XRPD pattern of obtained sugammadex corresponds to XRPD pattern depicted in Figure 1. Example 3: Purification of sugammadex

199 g of sugammadex prepared according to a procedure disclosed in example 4 of WO2017144734 application was suspended in 1526 ml of water/ethanol (1:4 vokvol) mixture. The suspension was heated to 50°C. 22 ml of ethylacetate was added to the suspension and the suspension was stirred for 60 minutes at 50°C. The suspension was cooled to 25°C and filtered. The filtration cake was washed with 3x300 ml of ethanol. Isolated sugammadex was dried at 85°C to yield 172 g of sugammadex. XRPD pattern of obtained sugammadex corresponds to XRPD pattern depicted in Figure 1.

Example 4: Purification of sugammadex

66 g of sugammadex prepared according to a procedure disclosed in example 4 of

WO2017144734 application was suspended in 508 ml of water/2-propanol (1:4 vokvol) mixture. The suspension was heated at 50°C. 8 ml of propylacetate was added to the suspension and the suspension was stirred for 60 minutes at 50°C. The suspension was cooled to 25 °C and filtered. The filtration cake was washed with 3x100 ml of 2-propanol. Isolated sugammadex was dried at 85°C to yield 56 g of sugammadex. XRPD pattern of obtained sugammadex corresponds to XRPD pattern depicted in Figure 1.

Example 5: Purification of sugammadex

66 g of sugammadex prepared according to a procedure disclosed in example 4 of

WO2017144734 application was suspended in 508 ml of water/ethanol (1:4 vokvol) mixture. The suspension was heated at 50°C. 8 ml of methylacetate was added to the suspension and the suspension was stirred for 60 minutes at 50°C. The suspension was cooled to 25°C and filtered. The filtration cake was washed with 3x100 ml of ethanol. Isolated sugammadex was dried at 85°C to yield 57 g of sugammadex. XRPD pattern of obtained sugammadex corresponds to XRPD pattern depicted in Figure 1.

Example 6: Purification of sugammadex

66 g of sugammadex prepared according to a procedure disclosed in example 4 of WO2017144734 application was suspended in a mixture comprising 406 ml of methanol and

101 ml of water and 8 ml of ethylacetate. The suspension was heated at 50°C and was stirred at this temperature for 60 minutes. The suspension was cooled to 25°C and filtered. The filtration cake was washed with 3x100 ml of methanol. Isolated sugammadex was dried at 85°C to yield 55 g of sugammadex. XRPD pattern of obtained sugammadex corresponds to

XRPD pattern depicted in Figure 1. Example 7: Comparison of osmolalities and sodium content of sugammadex samples

In the following table the osmolalities of sugammadex solution and sodium content in sugammadex samples are summarized. It can be concluded that by using the process according to presented invention both osmolality and sodium content values are significantly decreased when comparing to sugammadex prepared according to the prior art.

Osmolality was measured using OSMOMAT 3000 (Gonotec), a solution (concentration 108 mg/ml) of sugammadex in water was used. The osmolality of the solution was obtained by comparison of freezing point of the sugammadex solution and the freezing point of water.

The sodium content was obtained by titration of sugammadex solution in glacial acetic acid (concentration 3 mg/ml) using 0.1 M solution of HCIO4 using Titrator 794 DMS Titrino, Metrohm. The endpoint (VEQ) was determined potentiometrically.

Theoretical amount (% wt) of sodium in sugammadex is 8.5 % (wt/wt).