Nevirapine Concentrations in Saliva Measured by Thin Layer Chromatography and Self-Reported Adherence in Patients on Antiretroviral Therapy at Kilimanjaro Christian Medical Centre, Tanzania

Abstract

Thin layer chromatography (TLC) can be used to perform therapeutic drug monitoring in resource-limited settings, where more expensive analytical methods, such as high-performance liquid chromatography or liquid chromatography-mass spectrometry, are not feasible. The aim of this cross-sectional study was to compare saliva concentrations of nevirapine (NVP) with self-reported adherence in patients on NVP-containing antiretroviral treatment at Kilimanjaro Christian Medical Centre, Moshi, Tanzania. HIV-infected patients using a combination of zidovudine + lamivudine + NVP, or stavudine + lamivudine + NVP, for more than 4 weeks were included. Saliva samples were collected using dental cotton rolls impregnated with citric acid (20 mg). Saliva NVP concentrations were analyzed using TLC. Adherence to ARV medication was assessed by self-reporting using the Morisky scale. Of the 91 study participants, 79 (86.8%) had therapeutic saliva NVP concentrations (ie, >1.75 mg/L) and 12 (13.2%) had subtherapeutic concentrations. Self-reported adherence among the study participants was high in 62 participants (68.1%), moderate in 24 (26.4%), and low in 5 (5.5%). Fifty-seven (91.9%) of the study participants with high self-reported adherence had therapeutic saliva NVP concentrations. Of the 5 participants with low self-reported adherence, 3 had therapeutic NVP concentrations. A high proportion of patients had therapeutic NVP saliva concentrations as measured by TLC, which showed a good agreement with self-reported adherence.