Development of a Validated LC-MS/MS Method for Simultaneous Quantification of Antiretroviral Drugs in Plasma Samples from HIV Patients in Taraba State

Therapeutic drug monitoring of antiretroviral agents is a valuable tool for optimising HIV treatment outcomes, particularly in resource-limited settings where drug resistance development and treatment failure are more prevalent. Simultaneous quantification of multiple ARV drugs in a single analytical run reduces cost and sample volume requirements. This study developed and validated a liquid chromatography-tandem mass spectrometry method for the simultaneous determination of efavirenz, lamivudine, and tenofovir in dried blood spot samples from HIV-positive patients receiving treatment at the ART clinic of Taraba State Specialist Hospital, Jalingo. Dried blood spots were extracted by protein precipitation with methanol-water and analysed on a C18 column using gradient elution. Method validation followed the EMA guideline on bioanalytical method validation, assessing selectivity, linearity, accuracy, precision, matrix effects, and stability. The method showed linear response over the clinically relevant concentration ranges for all three compounds with correlation coefficients above 0.998. Accuracy ranged from 94.8 to 107.2% across all analytes and quality control levels. Matrix effects were within acceptable limits following isotope-labelled internal standard correction. The validated method was applied to monitor plasma drug concentrations in 48 patients, revealing subtherapeutic efavirenz levels in 21% of the cohort, which correlated with higher viral load measurements. This method provides a practical and sensitive tool for ARV therapeutic drug monitoring in North East Nigerian clinical settings. Keywords: LC-MS/MS, antiretroviral drugs, therapeutic drug monitoring, HIV, Taraba State.