Simultaneous estimation of novel antihypertensive drug combination efonidipine hydrochloride and telmisartan using liquid chromatographic method

The combination of efonidipine hydrochloride and telmisartan is used in the treatment of hypertension. Simultaneous estimation of both drugs in marketed formulation was carried out by using an accurate and precise isocratic RP – HPLC method. Symmetry® C18 (250 × 4.6 mm, 5 µm) column as a stationary phase and acetonitrile (ACN): 0.05 M Potassium dihydrogen phosphate buffer (75:25, v/v) as a mobile phase with a flow rate of 1 ml/min was used for the study. Detection was carried out at 251 nm. The developed method was found to be linear in the concentration range of 0.2 – 15 µg/ml for both drugs with correlation co-efficient of 0.998 for efonidipine and 0.996 for telmisartan. The proposed method was validated as per ICH Q 2 (R1) guideline. Forced degradation study was carried out to find out instrinsic stability of both the molecules. Efonidipine was found to be susceptible to base hydrolysis and oxidative stress degradation while telmisartan was stable in acid-base hydrolysis, oxidative stress, dry heat and photo stability testing conditions. Drug content in tablet dosage form is determined by proposed method where it exhibited good recovery which shows the applicability of method for analysis of combination of drugs.