Effect of High Protein Diet on Pharmacokinetic Parameters of Theophylline in Healthy Thai Volunteers

Abstract

Objectives: To examine effects of high protein diet on pharmacokineticsof theophylline in healthy Thai volunteers. Method: Eighthealthy males underwent two study phases, in which different typesof diet were offered. Normal protein diet (protein content 15%; NP)and high protein diet (protein content 20%; HP) were provided in thefirst and second phase, respectively. In each phase, participantsconsumed the test meals for 10 consecutive days. On day 11,theophylline (375 mg) was administered as a single oral dose. Bloodand saliva were collected for 48 hours post administration.Theophylline concentration in blood and saliva were quantitativelydetermined by HPLC method. Pharmacokinetic parameters(maximum plasma concentration (Cmax), area under plasmaconcentration-time curve (AUC0-∞), time to maximum concentration(Tmax), elimination half-life (t1/2) and clearance (Cl)) were analyzedusing WinNonlin Version 1.1., and statistically tested by paired t-test.Results: There were no significant differences betweenpharmacokinetic parameters obtained from NP group compared toHP group. Saliva theophylline were 65.5% (NP) and 65.7% (HP) ofplasma level, which was not statistically significant (P = 0.473).Conclusions: Diet containing 20% protein had no effects onpharmaco-kinetics of oral theophylline in healthy Thai volunteers.Keywords: theophylline, pharmacokinetic, high protein diet