Pharmacokinetics of single doses of phenobarbital given intravenously and orally to dogs.
Pharmacokinetics of phenobarbital was studied in 10 healthy dogs after single IV or oral administration. Phenobarbital sodium was administered IV to 5 dogs in group A (5.5 mg/kg of body weight) and 5 dogs in group B (15 mg/kg). Serial venous blood samples (n = 21) were collected from each dog before (base line) and after the administration of phenobarbital sodium for pharmacokinetic evaluation. After a 30-day resting period, 3 dogs in group A and 3 in group B were randomly selected and used for an IV crossover treatment. The IV treatment mean half-life of phenobarbital sodium was 92.6 +/- 23.7 and 72.3 +/- 15.5 hours, whereas mean total clearance was 5.60 +/- 2.31 and 6.66 +/- 0.78 ml/hr/kg for doses of 5 and 15 mg/kg, respectively. The mean residence time was 124 +/- 34 hours and 106 +/- 23 hours for the 5.5 and 15 mg/kg, IV doses, respectively. Significant differences (P greater than 0.05) were not observed in pharmacokinetic parameters between the 2-dose study. After a 35-day resting period, dogs in groups A and B were treated as described for the single IV treatment, except that they were given a phenobarbital tablet orally. Serial venous blood samples (n = 24) were collected before (base line) and after the administration of phenobarbital. Mean bioavailability was 88.1 +/- 12.4% and 96.8 +/- 9.0%, half life of absorption was 0.263 +/- 0.185 and 0.353 +/- 0.443 hour, and lag time was 0.611 +/- 0.683 and 0.741 +/- 0.554 hour for groups A and B, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
D000284:Administration, Oral; D000704:Analysis of Variance; D000818:Animals; D001682:Biological Availability; D004285:Dogs / Q000378:metabolism*; D005260:Female; D006207:Half-Life; D007262:Infusions, Intravenous; D007700:Kinetics; D008297:Male; D010634:Phenobarbital / Q000008:administration & dosage / Q000378:metabolism*; D011897:Random Allocation; D012044:Regression Analysis
D010634:Phenobarbital