Chloroquine Phosphate Tablets
Action and use
Antiprotozoal (malaria).
Definition
Chloroquine Phosphate Tablets contain Chloroquine Phosphate.
Content of chloroquine phosphate, C18H26ClN3,2H3PO4
92.5 to 107.5% of the stated amount.
Identification
TESTS
Dissolution
Comply with the requirements for Monographs of the British Pharmacopoeia in the dissolution test for tablets and capsules, Appendix XII B1, using as the medium 900 mL of 0.1m hydrochloric acid and rotating the basket at 100 revolutions per minute. Withdraw a sample of 10 mL of the medium. Measure the absorbance of a layer of suitable thickness of the filtered sample, suitably diluted if necessary, at the maximum at 344 nm, Appendix II B. Calculate the total content of chloroquine phosphate, C18H26ClN3,2H3PO4, in the medium taking 371 as the value of A(1%, 1 cm) at the maximum at 344 nm.
Related substances
Carry out the method for thin-layer chromatography, Appendix III A, using silica gel GF254 as the coating substance and a mixture of 50 volumes of chloroform, 40 volumes of cyclohexane and 10 volumes of diethylamine as the mobile phase. Apply separately to the plate 2 µL of each of the following solutions. For solution (1) shake a quantity of the powdered tablets containing 1 g of Chloroquine Phosphate with 20 mL of water for 30 minutes, centrifuge and use the supernatant liquid; if necessary filter through a glass fibre paper. For solution (2) dilute 1 mL of solution (1) to 100 mL with water. For solution (3) dilute 25 mL of solution (2) to 50 mL with water. After removal of the plate, allow it to dry in air and examine under ultraviolet light (254 nm). Any secondary spot in the chromatogram obtained with solution (1) is not more intense than the spot in the chromatogram obtained with solution (2) and not more than one such spot is more intense than the spot in the chromatogram obtained with solution (3).
Assay
Weigh and powder 20 tablets. Dissolve a quantity of the powder containing 0.5 g of Chloroquine Phosphate in 20 mL of 1m sodium hydroxide and extract with four 25-mL quantities of chloroform. Combine the chloroform extracts and evaporate to a volume of about 10 mL. Add 40 mL of anhydrous acetic acid and carry out Method I for non-aqueous titration, Appendix VIII A, determining the end point potentiometrically. Each mL of 0.1m perchloric acid VS is equivalent to 25.79 mg of C18H26ClN3,2H3PO4.
250 mg of Chloroquine Phosphate is approximately equivalent to 155 mg of chloroquine.