Cosolvents and Surfactants Effect on the Rate Constant (Log K) of ‎Efavirenz in Aqueous Solution

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Efavirenz is a non-nucleoside reverse transcriptase inhibitor clinically used for the ‎treatment of patients with human immunodeficiency virus (HIV) as it is effective in ‎reducing viral load in HIV-positive patients.‎ The objective of the present study was to investigate cosolvents and surfactants effect on ‎efavirenz under basic conditions.‎ The breakdown of efavirenz in basic aqueous solution of cosolvents and surfactants at 60°C ‎‎±0.2 was studied.‎ The breakdown was determined by UV spectrophotometry. The drug was seen to follow the ‎apparent first order rate kinetics and rate constant for the degradation were obtained from ‎plot of logarithm percent drug remaining versus time.‎ The kinetic reaction was shown to be hydroxide ion catalysed.‎ A significant increase in the stability of efavirenz was noted with the cosolvents and ‎surfactants investigated. The results obtained from the study suggested that cosolvents and ‎surfactants could be used to formulate and stabilise liquid pharmaceutical dosage forms of ‎efavirenz under basic conditions‎‎‎.