In vitro drug-drug interaction study between Montelukast Sodium and Amlodipine Besylate at gastric and intestinal pH

Kazi Ashfak Ahmed Chowdhury, Mohammad Shah Hafez Kabir, Tanvir Ahmad Chowdhury, Mohammed Munawar Hossain, A.T.M. Mostafa Kamal, Md. Rafi-Uz-Zaman Akanda, Abul Hasanat

Present study was aimed to evaluate the in vitro complexation nature and strength of complex which may be formed due to interaction between Montelukast Sodium and Amlodipine Besylate. The interaction of Montelukast Sodium and Amlodipine Besylate has been studied in aqueous systems at a fixed temperature (37⁰C) at both gastric pH (pH 1.0 and pH 3.0) and intestinal pH (pH 6.5 and pH 6.8) by using some physical methods as spectral observation, Job’s method of continuous variation, Ardon’s method. From spectrophotometric study, Montelukast Sodium and Amlodipine Besylate give different spectra when Montelukast Sodium mixed with Amlodipine Besylate in 1:1 ratio the intensity of the spectra of Montelukast Sodium change remarkably due to interaction. The jobs plot was obtained by plotting absorbance difference against the mole fraction of the each drug at pH 1.0, pH 3.0, pH 6.5 and pH 6.8. Montelukast Sodium strong 1:1 complex with Amlodipine Besylate and lower spectra indicate the formation of 1:1 complexes of Montelukast Sodium with Amlodipine Besylate. These may indicate strong kinetics of complexation between Montelukast Sodium with Amlodipine Besylate. The value of stability constant for the complexation of Montelukast Sodium with Amlodipine Besylate at pH 1.0, pH 3.0, pH 6.5 and pH 6.8 were obtained from the spectral data using Ardon’s plot. The value of stability constant for the drug-drug system at pH pH 1.0, pH 3.0, pH 6.5 and pH 6.8 are 1.9412, 2.0323, 2.0952 and 2.2203 respectively. At pH 6.8 it is found that Montelukast Sodium form relatively stable complex with Amlodipine Besylate (stability constant 2.2203) is high in comparison to pH 1. It can therefore be concluded that a careful consideration is needed during concurrent administration of Montelukast Sodium with Amlodipine Besylate.