Co-beneldopa Capsules

Benserazide Hydrochloride and Levodopa Capsules

Dopa decarboxylase inhibitor + dopamine precursor; treatment of Parkinson's disease.

Co-beneldopa Capsules contain Benserazide Hydrochloride and Levodopa in the proportions, by weight, 1 part benserazide to 4 parts levodopa.

The capsules comply with the requirements stated under Capsules and with the following requirements.

95.0 to 105.0% of the stated amount.

95.0 to 105.0% of the stated amount.

A. Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions.

(1) Shake a quantity of the capsule contents containing 0.2 g of Levodopa with 40 mL of 0.1m hydrochloric acid for 10 minutes, filter and use the filtrate.

(2) 0.5% w/v of levodopa BPCRS in 0.1m hydrochloric acid.

(3) 0.142% w/v of benserazide hydrochloride BPCRS in 0.1m hydrochloric acid.

(a) Use a precoated cellulose plate (Merck plates are suitable).

(b) Use the mobile phase as described below.

(c) Apply 2 µL of each solution.

(d) Develop the plate to 10 cm.

(e) After removal of the plate, dry in a current of warm air for 5 minutes, spray with dilute phosphomolybdotungstic reagent, dry in a current of warm air for 30 seconds and spray with a 10% w/v solution of sodium hydroxide.

10 volumes of a 10% v/v solution of hydrochloric acid, 20 volumes of water and 70 volumes of propan-2-ol.

The chromatogram obtained with solution (1) shows two clearly separated spots, the spot with the higher Rf value corresponding to the spot in the chromatogram obtained with solution (2) and the spot with the lower Rf value corresponding to the spot in the chromatogram obtained with solution (3).

B. In the Assay, the chromatogram obtained with solution (1) exhibits two peaks with the same retention times as those due to benserazide and levodopa in the chromatogram obtained with solution (2).

Comply with the requirements for Monographs of the British Pharmacopoeia in the dissolution test for tablets and capsules, Appendix XII B1.

(a) Use Apparatus 2, rotating the basket at 100 revolutions per minute.

(b) Use 900 mL of 0.1m hydrochloric acid, at a temperature of 37°, as the medium.

Carry out the method for liquid chromatography, Appendix III D, using the following solutions.

(1) After 45 minutes withdraw a sample of 10 mL of the medium and filter. Use the filtered medium, diluted with the mobile phase if necessary, expected to contain 0.04 mg of Levodopa per mL.

(2) Dilute 1 volume of a 0.1% w/v solution of levodopa BPCRS in 0.1m orthophosphoric acid to 25 volumes with the mobile phase.

The chromatographic conditions described under Assay may be used. Disregard the peak due to benserazide.

Calculate the total content of levodopa, C₉H₁₁NO₄, in the medium using the declared content of C₉H₁₁NO₄ in levodopa BPCRS.

A. Carry out the method for liquid chromatography, Appendix III D, using the following solutions prepared in mobile phase that has been cooled to 4° and injected immediately.

(1) Shake a quantity of the contents of the capsules containing the equivalent of 0.1 g of benserazide with 100 mL, mix with the aid of ultrasound for 3 minutes, shaking occasionally, and filter through a 0.45-µm filter, discarding the first 5 mL of filtrate.

(2) 0.0005% w/v of benserazide impurity A BPCRS.

(3) 0.0005% w/v of each of benserazide hydrochloride BPCRS and benserazide impurity A BPCRS.

(a) Use a stainless steel column (12.5 cm × 4 mm) packed with octylsilyl silica gel for chromatography (5 µm) (Lichrospher RP8 is suitable).

(b) Use isocratic elution and the mobile phase described below.

(c) Use a flow rate of 1.2 mL per minute.

(d) Use an ambient column temperature.

(e) Use a detection wavelength of 220 nm.

(f) Inject 20 µL of each solution.

(g) For solution (1) allow the chromatography to proceed for nine times the retention time of benserazide.

Dissolve 4.76 g of potassium dihydrogen orthophosphate in 800 mL of water, adding 200 mL of acetonitrile and 1.22 g of sodium decanesulfonate and adjusting the pH to 3.5 with orthophosphoric acid.

The test is not valid unless, in the chromatogram obtained with solution (3) the resolution factor between the two principal peaks is at least 2.0.

In the chromatogram obtained with solution (1):

the area of any peak corresponding to benserazide impurity A is not greater than the area of the principal peak in the chromatogram obtained with solution (2) (0.5%);

the area of any other secondary peak is not greater than the area of the peak due to benserazide in the chromatogram obtained with solution (3) (0.5%);

the sum of the areas of any secondary peaks is not greater than twice the area of the peak due to benserazide in the chromatogram obtained with solution (3) (1%).

Disregard any peak with an area less than 0.1 times the area of the peak due to benserazide in the chromatogram obtained with solution (3) (0.05%).

B. Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions.

(1) Prepare immediately before use; shake a quantity of the contents of the capsules containing 0.1 g of Levodopa with 10 mL of a mixture of equal volumes of anhydrous formic acid and methanol.

(2) Dilute 1 volume of solution (1) to 200 volumes with methanol.

(3) Equal volumes of solution (1) and a solution prepared by dissolving 30 mg of l-tyrosine in 1 mL of anhydrous formic acid and diluting to 100 mL with methanol.

(a) Use a precoated cellulose plate (Merck plates are suitable).

(b) Use the mobile phase as described below.

(c) Apply separately to the plate, as bands 20 mm long, 10 µL of each of solutions (1) and (2) and 20 µL of solution (3) and dry in a current of air.

(d) Develop the plate to 15 cm.

(e) After removal of the plate, dry in a current of warm air, spray with a freshly prepared mixture containing equal volumes of a 10% w/v solution of iron(iii) chloride hexahydrate and a 5% w/v solution of potassium hexacyanoferrate(iii) and examine the plate immediately.

10 volumes of a 10% v/v solution of hydrochloric acid, 20 volumes of water and 70 volumes of propan-2-ol.

Any secondary band in the chromatogram obtained with solution (1) is not more intense than the band in the chromatogram obtained with solution (2) (0.5%). The test is not valid unless the chromatogram obtained with solution (3) shows a distinct band, at a higher Rf value than the principal band, which is more intense than the band in the chromatogram obtained with solution (2).

Carry out the method for liquid chromatography, Appendix III D, using the following solutions.

(1) Shake a quantity of the mixed contents of 20 capsules containing 0.1 g of Levodopa with 80 mL of 0.1m orthophosphoric acid for 5 minutes, mix with the aid of ultrasound for 30 minutes, cool, add sufficient 0.1m orthophosphoric acid to produce 100 mL and mix. Filter the resulting solution through a 0.45-µm filter (Whatman GF/C is suitable), discarding the first 5 mL of filtrate, and dilute 10 volumes of the filtrate to 100 volumes with the mobile phase.

(2) Dissolve 28.7 mg of benserazide hydrochloride BPCRS and 0.1 g of levodopa BPCRS in sufficient 0.1m orthophosphoric acid to produce 100 mL, mix and dilute 10 volumes of the resulting solution to 100 volumes with the mobile phase.

(a) Use a stainless steel column (25 cm × 4 mm) packed with octylsilyl silica gel for chromatography (5 µm) (Lichrospher RP8 is suitable).

(b) Use isocratic elution and the mobile phase described below.

(c) Use a flow rate of 1.2 mL per minute.

(d) Use an ambient column temperature.

(e) Use a detection wavelength of 220 nm.

(f) Inject 20 µL of each solution.

Dissolve 4.76 g of potassium dihydrogen orthophosphate in 800 mL of water, adding 200 mL of acetonitrile and 1.22 g of sodium decanesulfonate and adjusting the pH to 3.5 with orthophosphoric acid.

The chromatogram obtained with solution (2) shows two principal peaks; the retention time of the peak due to benserazide is about three times that of the peak due to levodopa.

Calculate the content of C₁₀H₁₅N₃O₅ and of C₉H₁₁NO₄ in each capsule using the declared contents of C₁₀H₁₅N₃O₅ in benserazide hydrochloride BPCRS and of C₉H₁₁NO₄ in levodopa BPCRS.

Co-beneldopa Capsules should protected from moisture.

The quantity of Benserazide Hydrochloride is stated in terms of the equivalent amount of benserazide.