Chlorpropamide Tablets
Action and use
Inhibition of ATP-dependent potassium channels (sulfonylurea); treatment of diabetes mellitus.
Definition
Chlorpropamide Tablets contain Chlorpropamide.
Content of chlorpropamide, C10H13ClN2O3S
92.5 to 107.5% of the stated amount.
Identification
Extract a quantity of the powdered tablets containing 1 g of Chlorpropamide with five 4-mL quantities of acetone, filter and evaporate the filtrate carefully to dryness on a water-bath. The infrared absorption spectrum of the residue, Appendix II A, is concordant with the reference spectrum of chlorpropamide (RS 057).
Tests
Dissolution
Comply with the requirements for Monographs of the British Pharmacopoeia in the dissolution test for tablets and capsules, Appendix XII B1.
Calculate the total content of chlorpropamide, C10H13ClN2O3S, in the medium taking 469 as the value of A(1%, 1 cm) at the maximum at 230 nm.
Related substances
Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions.
11.5 volumes of 13.5m ammonia, 30 volumes of cyclohexane, 50 volumes of methanol and 100 volumes of dichloromethane.
The test is not valid unless the chromatogram obtained with solution (6) shows three clearly separated spots with Rf values of approximately 0.4, 0.6 and 0.9 corresponding to chlorpropamide, 4-chlorobenzenesulfonamide and 1,3-dipropylurea, respectively.
In the chromatogram obtained with solution (1):
any spot corresponding to 4-chlorobenzenesulfonamide is not more intense than the spot in the chromatogram obtained with solution (2) (0.3%);
any spot corresponding to 1,3-dipropylurea is not more intense than the spot in the chromatogram obtained with solution (3) (0.3%);
any other secondary spot is not more intense than the spot in the chromatogram obtained with solution (4) (0.3%);
not more than two such spots are more intense than the spot in the chromatogram obtained with solution (5) (0.1%).
Assay
Weigh and powder 20 tablets. Shake a quantity of the powder containing 0.25 g of Chlorpropamide with 40 mL of methanol for 20 minutes, add sufficient methanol to produce 50 mL, mix, filter and dilute 5 mL of the filtrate to 100 mL with 0.1m hydrochloric acid. Dilute 10 mL of this solution to 250 mL with 0.1m hydrochloric acid and measure the absorbance of the resulting solution at the maximum at 232 nm, Appendix II B. Calculate the content of C10H13ClN2O3S taking 598 as the value of A(1 cm, 1%) at the maximum at 232 nm.