Day-night and individual differences in response to constant-rate ranitidine infusion.
Twelve ulcer patients with inactive disease received constant-rate infusions of ranitidine, in doses of 6.25 and 10.0 mg/hr, during separate 24-h spans. Gastric pH and serum ranitidine concentrations were monitored. Serum ranitidine concentrations did not vary significantly after attainment of steady-state. For the group, gastric acidity was controlled above pH 4 during the day; however, at night, when gastric acid secretion was greatest under placebo conditions, ranitidine less effectively controlled gastric pH. There was individual variation in response to ranitidine. Patients (8/12) evidencing control of gastric acidity (pH greater than or equal to 4) for at least 16 h when infused with ranitidine (6.25 mg/h) were considered responders. Those (4/12) not so well controlled were designated poor responders. With parenteral infusion of 6.25, as well as 10.0 mg/h ranitidine, responders evidenced a relatively high 24-h mean pH and only minor day-night variation in gastric acidity. In contrast, poor responders were characterized by a low 24-h mean pH and high-amplitude circadian variation in gastric acidity. Poor responders evidenced statistically significant (p less than 0.05) lower gastric pH responses to parenteral infusions than did responders. A similar, significant difference between the two groups was observed when the percentage of time that gastric pH was maintained below 4 was considered. Differences between responders and poor responders to ranitidine infusion are unknown. Since Zollinger-Ellison syndrome patients were not included in the study, observed differences in drug response cannot be ascribed to hypersecretion of gastric acid.
White
C
C
Department of Pharmaceutics, University of Houston, School of Pharmacy, Texas 77030.
Smolensky
M H
MH
Sanders
S W
SW
Buchi
K N
KN
Moore
J G
JG
D000328:Adult; D000704:Analysis of Variance; D002940:Circadian Rhythm; D004381:Duodenal Ulcer / Q000503:physiopathology*; D015738:Famotidine / Q000008:administration & dosage* / Q000494:pharmacology; D005744:Gastric Acid / Q000378:metabolism*; D006801:Humans; D007262:Infusions, Intravenous; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D011899:Ranitidine / Q000008:administration & dosage* / Q000493:pharmacokinetics / Q000494:pharmacology
D015738:Famotidine; D011899:Ranitidine