The disposition of theophylline in camels after intravenous administration

The pharmacokinetics of theophylline were,determined after an intravenous ( i.v.) dose of 2.36 mg/kg in six camels' and 4.72 mg/kg body weight in three camels. The data obtained (median and range) for the low and high dose, re spectively, were as follows: the distribution half-lives (t(1/2 alpha)) wer e 1.37 (0.64-3.25) and 2.66 (0.83-3.5) h, the elimination half-lives (t(1/2 beta)) were 11.8 (8.25-14.9) and 10.4 (10.0-13.5) h, the steady state volu mes of distribution (V-ss) were 0.88 (0.62-1.54) and 0.76 (0.63-0.76) L/kg, volumes of the central compartment (V-c) were 0.41 (0.35-0.63) and 0.51 (0 .36-0.52) L/kg, total body clearances (Cl-t) were 62.3 (39.4-97.0) and 50.2 (47.7-67.4) mL/h.kg body weight and renal clearance (V-r) for the low dose was 0.6 (0.42-0.96) mL/ h.kg body weight. There was no significant differe nce in the pharmacokinetic parameters between the two doses., Theophylline protein binding at a concentration of 5 mu g/mL was 32.2 +/- 3.3%. Caffeine was identified as a theophylline metabolite but its concentration-in serum and urine was small. Based on the pharmacokinetic values obtained in this study, a dosage of 7.5 mg/ kg bodyweight administered by i.v. injection at 12 h intervals can be recommended. This dosing regimen should achieve an av erage steady state serum concentration of 10 mu g/mL with peak serum concen tration not exceeding 15 mu g/mL.