Development and Application of Liquid Chromatographic Method for Simultaneous Determination of Elvitegravir, Tenofovir Disoproxil Fumarate, Emtricitabine, and Cobicistat in Fixed Dosage Form
Introduction: Quad pill is fixed-dose combinations containing four drugs in a single tablet with the intention of reducing the number of tablets that need to be taken. Elvitegravir/ Cobicistat/ Emtricitabine/ Tenofovir disoproxil fumarate (“QUAD”) – is a complete regimen intended for treatment of HIV infection. Developing a single analytical method for the estimation of individual drugs in a quad pill is very challenging, due to the formation of drug-drug and drug-excipient interactions. Method: Chromatographic separation of the four antiviral drugs was achieved by using a gradient elution at a flow rate of 1.0 mL/min on Inertsil ODS 3V C18 column (250 m×4.6 mm, 5 μm particle size, 100Å pore size) at ambient temparature. Mobile phase A of the gradient solvent system was KH2PO4 (0.02M) in 1000 ml of water and by adjusting the pH to 2.5 with dilute orthophosphoric acid and mobile phase B was acetonitrile. UV detection at 240nm was employed to monitor the analytes. Results: A linear response was observed for emtricitabine over the concentration range 20-240 μg/mL, for tenofovir disoproxil fumerate over the concentration range of 30-360 μg/mL, for elvetegravir and cobicistat over the concentration range of 15-180 μg/mL. Limit of detection (LOD) for emtricitabine, Tenofovir disoproxil fumerate, elveltegravir and cobicisate were 0.02μg/ mL, 0.03μg/mL, 0.75μg/mL and 3μg/mL respectively. Limit of quantification (LOQ) for emtricitabine, Tenofovir disoproxil fumerate, elveltegravir and cobicisate were 0.06μg/mL, 0.09μg/mL, 2.25μg/mL and 9μg/mL respectively. Conclusion: The present study demonstrates the applicability of chromatographic method to develop a new, sensitive, single HPLC method for the simultaneous quantitative determination of four antiviral agents in fixed pharmaceutical dosage form.