Effect of grapefruit juice on the pharmacokinetics of theophylline in healthy male volunteers.
The effect of grapefruit juice (GFJ) on the pharmacokinetics of a single dose of theophylline was examined in an open crossover study. Healthy male volunteers were given sustained release theophylline (300 mg) along with 300 ml of either water or GFJ. Blood samples (2 ml) were collected at different time points from 0 to 48 h. Plasma was assayed for theophylline by HPLC and various pharmacokinetic parameters were calculated. Theophylline levels were lower at all time points with GFJ coadministration as compared to water but were significantly lower only during the absorption phase from 1 to 4 h. Although the pharmacokinetic parameters were not significantly different between the two groups, all values were reduced except Tmax which was slightly increased. The results indicate that patients may be advised not to consume GFJ when taking slow-release theophylline and monitoring of plasma theophylline levels in patients consuming GFJ might be helpful in better management of patient care.
Gupta
M C
MC
Department of Pharmacology, Postgraduate Institute of Medical Education & Research, Chandigarh, India.
Garg
S K
SK
Badyal
D
D
Malhotra
S
S
Bhargava
V K
VK
D000328:Adult; D019540:Area Under Curve; D001628:Beverages; D001993:Bronchodilator Agents / Q000493:pharmacokinetics*; D002957:Citrus; D018592:Cross-Over Studies; D003692:Delayed-Action Preparations; D004311:Double-Blind Method; D018565:Food-Drug Interactions; D006207:Half-Life; D006801:Humans; D008297:Male; D013806:Theophylline / Q000493:pharmacokinetics*
D001993:Bronchodilator Agents; D003692:Delayed-Action Preparations; D013806:Theophylline