In-vitro interaction studies of verapamil with fluoroquinolones using first order derivative UV spectrophotometry and RP-HPLC

Verapamil, a calcium channel blocker, is classified as a class IV anti-arrhythmic agent. It is used in the treatment of hypertension, as an important therapeutic agent for angina pectoris, ischemic heart disease, hypertension and hypertrophic cardiomyopathy. Many in-vivo studies have been carried out to find out the effects on concurrent use of calcium channel blocker with various groups of drugs. In the present paper an in-vitro approach was adapted to study the interaction of verapamil with commonly administered fluoroquinolones i.e. ciprofloxacin, levofloxacin, norfloxacin and sparfloxacin. The interaction studies were carried out in different simulated body fluids pH ranges from 1-9 at 37 °C. To perform these studies first-derivative UV spectrophotometric (using zero-crossing technique) and simultaneous RP-HPLC methods were developed and validated. HPLC analysis was conducted on Shim-pack CLC-ODS (6.0 X 150 mm) column. The mobile phase constituted of acetonitrile: water (45:55), whose pH was adjusted to 2.8 and pumped at a flow rate of 1.2 mL min^-1 at 230 nm. The results obtained from both methodologies indicated that the availability of verapamil was not affected by simultaneous administration of fluoroquinolones. Hence the two drugs could be safely administered concomitantly.