Tenofovir systemic exposure

Tenofovir systemic exposure refers to the levels of the drug tenofovir in the blood plasma, typically quantified by the area under the curve (AUC) or maximum concentration (Cmax) (Gilead Sciences, 2023). It is a pharmacokinetic measure rather than a biological target such as a receptor or enzyme. The actual therapeutic target of the active metabolite, tenofovir diphosphate, is the HIV-1 reverse transcriptase enzyme, where it acts as a chain terminator to inhibit viral replication (PubChem, 2024). High systemic exposure of tenofovir, particularly when administered as the prodrug tenofovir disoproxil fumarate (TDF), has been linked to clinical safety concerns including proximal renal tubulopathy and reductions in bone mineral density (StatPearls, 2023). In contrast, the prodrug tenofovir alafenamide (TAF) was developed to achieve lower systemic exposure while delivering higher concentrations of the active drug to target cells, thereby improving the safety profile (FDA, 2015). Monitoring systemic exposure is essential when tenofovir is co-administered with pharmacokinetic enhancers like ritonavir, which can significantly increase plasma levels and the risk of toxicity (NIH, 2023). This parameter is critical for evaluating drug-drug interactions and optimizing dosing regimens in patients with renal impairment. Overall, managing tenofovir systemic exposure is a key strategy in balancing the antiviral efficacy and long-term safety of HIV and HBV treatments.

Other names

Tenofovir plasma concentrationTenofovir AUCTenofovir pharmacokinetics

Not applicable; this is a pharmacokinetic parameter. The drug tenofovir acts as a nucleotide reverse transcriptase inhibitor (NRTI) (PubChem, 2024).