2. Effects on Other Gastrointestinal Secretions
Oral ranitidine does not affect pepsin secretion. Total pepsin output is reduced in proportion to the decrease in volume of gastric juice.
Oral ranitidine has no significant effect on pentagastrin-stimulated intrinsic factor secretion.
Ranitidine has little or no effect on fasting or postprandial serum gastrin.
- Gastric bacterial flora—increase in nitrate-reducing organisms, significance not known.
- Prolactin levels—no effect in recommended oral or intravenous (IV) dosage, but small, transient, dose-related increases in serum prolactin have been reported after IV bolus injections of 100 mg or more.
- Other pituitary hormones—no effect on serum gonadotropins, TSH, or GH. Possible impairment of vasopressin release.
- No change in cortisol, aldosterone, androgen, or estrogen levels.
- No antiandrogenic action.
- No effect on count, motility, or morphology of sperm.
Oral doses of 6 to 10 mg/kg per day in two or three divided doses maintain gastric pH>4 throughout most of the dosing interval.
In a multicenter, double-blind, controlled, US study of endoscopically diagnosed duodenal ulcers, earlier healing was seen in the patients treated with ranitidine as shown in Table 3.
|Ranitidine *||Placebo *|
|Number Entered||Healed/Evaluable||Number Entered||Healed/Evaluable|
In these studies, patients treated with ranitidine reported a reduction in both daytime and nocturnal pain, and they also consumed less antacid than the placebo-treated patients.
|Ulcer Healed||Ulcer Not Healed|
Foreign studies have shown that patients heal equally well with 150 mg twice daily and 300 mg at bedtime (85% versus 84%, respectively) during a usual 4-week course of therapy. If patients require extended therapy of 8 weeks, the healing rate may be higher for 150 mg twice daily as compared to 300 mg at bedtime (92% versus 87%, respectively).
Studies have been limited to short-term treatment of acute duodenal ulcer. Patients whose ulcers healed during therapy had recurrences of ulcers at the usual rates.
Ranitidine has been found to be effective as maintenance therapy for patients following healing of acute duodenal ulcers. In two independent, double-blind, multicenter, controlled trials, the number of duodenal ulcers observed was significantly less in patients treated with ranitidine (150 mg at bedtime) than in patients treated with placebo over a 12-month period.
|Double-blind, Multicenter, Placebo-Controlled Trials|
|Multicenter Trial||Drug||Duodenal Ulcer Prevalence||No. of Patients|
|% = Life table estimate. RAN — ranitidine. PLC = placebo.|
|0-4 Months||0-8 Months||0-12 Months|
|RAN||20% *||24% *||35% *||138|
|RAN||12% *||21% *||28% *||174|
As with other H2-antagonists, the factors responsible for the significant reduction in the prevalence of duodenal ulcers include prevention of recurrence of ulcers, more rapid healing of ulcers that may occur during maintenance therapy, or both.
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