A review of tenofovir and lamivudine dosing errors in patients on highly active anti retroviral therapy with renal impairment at the university teaching hospital in Lusaka,Zambia

Abstract

Objectives Drug dosing errors are common in patients with renal impairment and could cause adverse effects and poor outcomes. The study reviewed tenofovir and lamivudine dosing errors as a component of the highly active antiretroviral therapy (HAART) regimen in patients with renal impairment at the University Teaching Hospital (UTH) in Lusaka, Zambia. The dosages of drugs cleared renally should be adjusted according to creatinine clearance or glomerular filtration rate. The aim of the study was to determine the frequency of tenofovir and lamivudine dosing errors in patients on HAART with renal impairment at UTH. Methodology A retrospective cross sectional study which involved review of patient files of 76 study patients with renal impairment at the Adult infectious Diseases Center (AIDC) at UTH was undertaken. Data analysis was done using Statistical Package for Social Sciences (SPSS) version 16.0 and association between dosing errors and prescribed dose were executed using Pearson Chi-square tests. Outcome measures were compliance with manufacturers’ literature and Zambia Consolidated Guidelines for Treatment and Prevention of HIV Infection (2014). Documentation of drug regimen prescribed, dose and frequency were used to measure appropriateness of dose prescribed. Results This study did not reveal any tenofovir dosing errors. Tenofovir was dosed correctly in patients (100%, 3/3) with renal impairment. Lamivudine dosing errors were found to be 40% in patients on HAART with renal impairment. Lamivudine was under dosed in 8% of the patients and overdosed in 32% of the patients on HAART with renal impairment. A statistically significant association between the dose of lamivudine prescribed and dosing error type was observed (CI 95, p< 0.001). Conclusion Tenofovir dosing errors in patients on HAART with renal impairment are not prevalent while lamivudine dosing errors in the same patient population have a prevalence of 40% at the University Teaching Hospital.