Chimie médicale

Development and Validation for the Simultaneous Quantification of Prazosin, Amlodipine, Diltiazem and Verapamil in API, Dosage Formulation and Human Serum by RP-HPLC: Application to in vitro Interaction Studies

Abstract

Najma Sultana, Saeed Arayne M and Shabana Naz Shah

A novel reversed-phase liquid chromatographic method with UV detection for rapid and accurate simultaneous quantitation of prazosin (PRZ) and the key calcium channel blockers (CCBS), amlodipine besylate (AML), diltiazem hydrochloride (DIL) and verapamil hydrochloride (VER) in active pharmaceutical ingredients, pharmaceutical dosage formulations and human serum has been developed and validated according to ICH guidelines.

The reduced run time and low cost of analysis are additional merits of the method. This method showed the best resolution by using pre-packed Nucleosil® C18 (10 μm, 25 × 0.46 cm) column at ambient temperature. The mobile phase consisting of methanol:water:acetonitrile (55:35:10 v/v; pH adjusted to 2.65 with phosphoric acid) was pumped at a flow rate of 1.0 mL min-1 with an average operating pressure of 130 kg/cm2 and effluent was monitored at 238 nm. Linearity of the method in the concentration range 5-100 μg mL-1 for prazosin and 10-600 μg mL-1 for calcium channel blockers showed good linear relationships for all the analytes (R2 < 0.9998). The LLOD values were 32.8, 30.6, 54.2, 29.9 and LLOQ were 99.4, 92.6, 164.2, 90.5 ng mL-1 for PRZ, AML, DIL and VER respectively, as per ICH guide lines acceptance criteria of 98 - 102%.

The newly developed method has been successfully employed for studying the interactions between prazosin and ca-channel blockers at simulated human body conditions; the results envisage a positive interaction between the two classes of drugs, as the percent recovery of the drugs almost changed, which indicate that prazosin may not be safe to co-administer with these antihypertensive drugs