The pharmacokinetics of ranitidine in patients with chronic duodenal ulceration: a comparison of responders and non-responders.
The pharmacokinetics of orally administered ranitidine were studied in 17 male patients with chronic duodenal ulceration. The patients were divided into 2 groups, 10 responders and 7 nonresponders, on the basis of their endoscopic response to ranitidine treatment. The 10 responders were studied both after a single 150 mg dose (SD) and after multiple dosing (MD) with ranitidine 150 mg twice daily for 4 weeks. The area under the curve (AUC) and maximum concentration (Cmax) were significantly higher (p less than 0.01 and p less than 0.05, respectively) after MD than after SD, but the half-life (t1/2) and minimum concentration (Cmin) 12 h postdosing did not differ. The non-responders were studied after MD only and their pharmacokinetic characteristics were compared with those of responders. No differences between the 2 groups were found. However, 2 non-responders had particularly low plasma ranitidine levels and high acid output. Such patients may need larger doses of ranitidine for adequate suppression of gastric acid. Five patients (4 responders and 1 non-responder) received ranitidine 20 mg i.v. The drug followed a two-compartment model, with mean values for t1/2 beta, volume of distribution steady-state and total plasma clearance of 80 min, 701 and 680 ml/min, respectively. The oral bioavailability of ranitidine in these 5 patients showed wide variation (27-76%; mean 51%).
D000284:Administration, Oral; D000328:Adult; D000897:Anti-Ulcer Agents / Q000378:metabolism* / Q000627:therapeutic use; D004381:Duodenal Ulcer / Q000188:drug therapy / Q000378:metabolism*; D005663:Furans / Q000378:metabolism* / Q000627:therapeutic use; D005744:Gastric Acid / Q000378:metabolism; D006801:Humans; D007263:Infusions, Parenteral; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D010418:Pentagastrin; D011899:Ranitidine; D013997:Time Factors
D000897:Anti-Ulcer Agents; D005663:Furans; D011899:Ranitidine; D010418:Pentagastrin