LC and LC-MS methods for the investigation of polypills for the treatment of cardiovascular diseases. Part 1. Separation of active components and classification of their interaction/degradation products.

"Polypill" is a fixed-dose combination (FDC) containing three or more drugs in a single pill. The same is under development for the treatment and prevention of cardiovascular diseases. In the present study, gradient LC methods were developed for simultaneous determination of the possible components of a polypill, i.e., lisinopril, aspirin and one each among atenolol/hydrochlorothiazide and atorvastatin/simvastatin/pravastatin, in the presence of a total of 13 major interaction/degradation products. The drugs and the products were well separated using a reversed-phase (C-8) column and a mobile phase comprising of acetonitrile: phosphate buffer (pH 2.3). Other HPLC parameters were flow rate, 1 ml/min; detection wavelength, 210 nm; column oven temperature, 60 degrees C; and injection volume, 5 microl. The methods were validated for linearity, precision, accuracy, and specificity. These were further modified to make them compatible for LC-MS studies by removal of the phosphate buffer and adjustment of pH by formic acid. The suitability of the methods for LC-MS studies was established by matching the theoretical mass values of the drugs with those obtained experimentally. These methods were used to determine mass values of the major interaction/degradation products, which helped to know the source of their origin.