Development and optimization of analytical method for determination the antihypertensive drugs

The Losartan potassium (LOS) is a drug used in the treatment of hypertensive patients1. It is sold in Brazil commercially associated with Hydrochlorothiazide (HCTZ), and, according to ANVISA1, LOS is among the best selling drugs in the country. The development of analytical methods which are simple, fast, selective and sensitive is importante to ensure not only the quality of the products, as well as detect the counterfeiting and/or adulteration of drugs. In this context it is proposed the development, optimization and validation of reversed phase HPLC method, isocratic, with UV detection for the determination of LOS and HCTZ in pharmaceutical formulations. The optimization of the chromatographic conditions was performed using Central Composite experimental design. Figure 1 shows the response surface methodology obtained in the optimization studies of the variables flow rate and temperature of the column. Using the optimized conditions: C18 column with temperature of 40 °C, mobile phase consisting of water: acetonitrile (50:50) and flow rate 0.60 mL min-1, symmetrical peaks with optimal resolution were obtained Figure 2. Analytical curves were constructed in the concentration range of 0.5 to 3.0 μg mL -1 (r = 0.9999) for LOS and 5.0 to 30 μg mL -1 (r = 0.9996) for HCTZ. The method was applied on commercial samples with recovery rates between 96.0 - 103.0%. The validation, considering the merit parameters recommended by ANVISA, allowed to verify that the proposed method is safe and reliable.