Determination of antihypertensive drugs by using ratio difference spectrophotometric method

Abstract

An accurate, sensitive and time saving spectrophotometric method has been developed and validated for the determination of two antihypertensive drug mixtures. Mixture 1 contains spironolactone (SPIR), furosemide (FUR) and anthranilic acid (ANTH) (impurity of furosemide) and mixture 2 contains triamterene (TRI), hydrochlorothiazide (HCZ) and chlorothiazide (CZ) (impurity of hydrochlorothiazide). In mixture 1, the determination of drugs depends on dividing the spectrum of ternary mixture by the spectrum of 10 µg/mL of standard furosemide and then spironolactone and anthranilic acid were determined using the difference in amplitude between 242.3 and 254.6 nm, and between 250.8 and 242.4 nm in the ratio spectrum, respectively. On the other hand, furosemide could be determined by dividing the spectrum of ternary mixture by the spectrum of 10 µg/mL of standard spironolactone and then it was determined using the difference in amplitude between 244.8 and 229.7 nm in the ratio spectrum. In mixture 2, the determination of drugs depends on dividing the spectrum of ternary mixture by spectrum of 10 µg/mL of standard triamterene and then hydrochlorothiazide and chlorothiazide were determined using the difference in amplitude between 268.9 and 232.8 nm, and between 292.9 and 250.7 nm in the ratio spectrum, respectively. On the other hand, triamterene could be determined by dividing spectrum of ternary mixture by spectrum of 10 µg/mL of standard hydrochlorothiazide and then triamterene was determined using the difference in amplitude between 230.1 and 244 nm in the ratio spectrum. The developed analytical methods were validated regarding good accuracy and precision according to The International Conference on Harmonisation guidelines, and they were applied to pharmaceutical preparations in addition to laboratory prepared mixtures successfully. Statistically the results were compared with those obtained by reported method and no significant difference was found.