Population pharmacokinetics of an angiotensin II receptor antagonist, telmisartan, in healthy volunteers and hypertensive patients

OBJECTIVE: To describe the factors affecting pharmacokinetics of telmisartan, an angiotensin II receptor antagonist, a population pharmacokinetic (PPK) model has been developed based upon the data collected from healthy volunteers and hypertensive patients. METHODS: A total of 1566 plasma samples were collected from 20 healthy volunteers and 129 hypertensive patients, together with the demographic background. The data were analyzed by the NONMEM program using two-compartment model with first-order absorption. The robustness of the obtained PPK model was validated by the bootstrapping resampling method. RESULTS: The oral clearance (CL/F) was found to be associated with age, dose and alcohol consumption, but neither related to serum creatinine nor smoking history. The volume of distribution for the central compartment was related to age and dose, and the volume of distribution for the peripheral compartment was related to body weight and gender. The absorption rate constant (Ka) and the absorption lag time were described as function of dose. The CL/F decreased with advanced age. The CL/F decreased and Ka increased with higher dose, reflecting the super-proportional increase in the plasma levels of telmisartan. The AUC and C(max) values predicted by the present PPK model were well consistent with the observed values. The means of parameter estimates obtained with 200 bootstrap replicates were within 95-111% of the final parameter estimates from the original data set. CONCLUSION: A PPK model for telmisartan developed here well described the individual variability and exposure, and robustness of the model has been validated by the bootstrapping method.