Mark Mascolini, IAS News

A study of tenofovir concentrations in HIV-infected, antiretroviral-experienced children starting this nucleotide analogue found steady-state exposures that approach those seen in adults taking 300 mg daily – approximately 3000 ng . h/mL.

The trial began with 18 children stopping a failing regimen and starting only tenofovir. Incremental dosing with 75-mg tablets aimed for a target dose of 175 mg/m2; the median administered dose was 208 mg/m2. Single-dose studies found a geometric mean area under the concentration-time curve (AUC) of 2150 ng . h/mL and a mean maximum concentration of 266 ng/mL.

Children then added other drugs to their regimen on the basis of treatment history and resistance patterns. Four weeks later, steady-state pharmacokinetic studies in 16 children showed a geometric mean AUC of 2920 ng . h/mL, which was significantly higher than the AUC in the single-dose study (P = 0.0004). The geometric mean maximum concentration at steady state measured 302 ng/mL.

Source: International AIDS Society

http://www.ias.se/article/show.asp?article=2566

Ref: Hazra R, Balis FM, Tullio AN et al. Single-dose and steady-state pharmacokinetics of tenofovir disoproxil fumarate in human immunodeficiency virus-infected children. Antimicrobial Agents and Chemotherapy 2004; 48:124-129.