No change in calculated creatinine clearance after tenofovir initiation among Thai patients.

OBJECTIVES Thai patients have a lower average body weight than patients from western Europe or the USA. Tenofovir is largely prescribed at the standard dosage of 300 mg once daily: therefore, the per kilogram dose is higher in Thailand than in the USA. We asked the question whether this higher per kilogram dose was associated with more nephrotoxicity. METHODS Thai patients from the Staccato trial were treated with tenofovir/lamivudine combined with ritonavir-boosted saquinavir. Creatinine values were measured before the start of tenofovir and then every 12 weeks. Renal function was assessed using the Cockcroft-Gault formula and the MDRD formula. To compare CL(CR) before and after tenofovir, the t-paired or Wilcoxon signed rank tests were used. One-way analysis of variance and Spearman's correlation coefficient were used to study CL(CR) longitudinally. RESULTS CL(CR) remained stable after a median of 21 weeks on tenofovir (difference of +1.06 mL/min; 95% CI -2.7-4.8, P=0.58), even among patients with underlying diseases. The mean CL(CR) remained stable across time (P=0.17). CONCLUSIONS We did not find renal dysfunction on tenofovir among Thai patients included in the Staccato trial. Tenofovir could be safely prescribed at a standard dosage of 300 mg once daily in the Thai population.