Development and characterization of Telmisartan self-microemulsifying drug delivery system for bioavailability enhancement

Abstract

Telmisartan is a potent, long-lasting, nonpeptide antagonist of the angiotensin II type-1 (AT1) receptor that is indicated for the treatment of essential hypertension. It belongs to a class II drug in BCS classification i.e. low solubility and high permeability. One of the major problems with this drug is its low solubility in biological fluids which results into poor bioavailability after oral administration. The objective of present work was to develop a self microemulsifying drug delivery system (SMEDDS) to enhance the oral bioavailability of poorly water soluble Telmisartan. SMEDDS is a mixture of oil, surfactant, and cosurfactant, which are emulsified in aqueous medium under gentle digestive motility in the gastrointestinal tract. Psuedoternary phase diagrams were constructed to identify the efficient self-emulsifying region. A SMEDDS were further evaluated for its percentage transmittance, emulsification time, drug content, phase separation, globule size, zeta potential, pH, refractive index, X-ray diffraction, Differential scanning calorimetry and in vitro dissolution studies. Optimized formulation was also compared with marketed product (Telma 20) in male spraguedawley rats. The pharmacokinetic study exhibited 1.54 fold increase in the oral bioavailability of Telmisartan SMEDDS compared with the Marketed product.