Interaction of Losartan potassium with the micelles of Triton X 100

Article history: Received on: 02/03/2013 Revised on: 29/03/2013 Accepted on: 15/04/2013 Available online: 12/05/2013 This study is an investigation of the physicochemical interaction of Losartan potassium (LST K), an angiotensinII receptor (type AT1) antagonist, with micelles of triton X, a nonionic surfactant. The effect of micelles on the spectral properties of LSTK was monitored on at pH 7.4 and at room temperature. The spectrum of LST K showed gradual and progressive bathochromic and hypochromic shift in presence of increasing concentrations of triton X 100. The binding constant Kb of LST K to triton X 100 micelles was calculated using the differential absorbance at λ = 225 nm& was found to be 4.13 ± 0.35 ×10 5 mol -1 L. By using pseudo-phase model, the partition coefficient between the bulk water and Triton X 100 micelles, Kx, was calculated from both differential absorbance Δ A225, Kx = 2.26 ±0.12 x10 5 mol -1 L. The binding of LST K to Triton X 100 micelles implied a shift in drug acidity constant (Δ pKa = 0.8)