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Biomedical subjects

R L McIsaac

Publications and source records attributed to R L McIsaac.

11 recordsLinked to original sources
PubMed1991

Ranitidine in the treatment of duodenal ulcer disease: relationship between antisecretory effect and ulcer healing rate.

The relationship between drug-induced suppression of intragastric acidity and the rate of duodenal ulcer healing was examined using data for a single drug, ranitidine, from 156 clinical trials involving 16,362 patients together with data on acid suppression from 37 studies of intragastric acidity in 630 subjects. In these studies ranitidine was given in doses ranging from 150 mg to 1200 mg per day administered in 9 different dosage regimens. The overall percentage of patients whose duodenal ulcers healed at 2 and 4 weeks on the different regimens was highly correlated with the percentage suppression of 24-hour intragastric acidity induced by different regimens. Thus the therapeutic benefit of a given ranitidine dosage regimen in healing duodenal ulcers relates directly to its antisecretory effect.

Drug Administration Schedule↗
PubMed1991

The evolution of peptic ulcer therapy. A role for temporal control of drug delivery.

The treatment of acid peptic disease has involved a series of attempts to control gastric acid secretion in order to heal and to prevent recurrence of duodenal ulcers. Early treatment attempted to heal by neutralizing gastric acid with diet modification, the Sippy diet, and Doll's milk drip. Just before the turn of the century, surgeons began performing gastric resections. In 1943, Dr. Lester Dragstedt performed the first truncal vagotomy to limit cholinergic stimulation of gastric acid secretion. This led to surgery that combined gastric resections with vagotomy. In 1970, the first parietal cell vagotomy was performed. This microsurgical technique limited vagal initiation of acid secretion while minimizing the impact on other gastrointestinal functions. By the 1960s, pharmacological intervention included antacids to neutralize acid and anticholinergics to reduce the amount of acid produced. These treatments varied in their effectiveness, and some of them caused significant side effects. In 1976, treatment of acid peptic disease began a new phase with the introduction of the first H2 receptor antagonist, cimetidine. Ranitidine, the second H2 receptor antagonist, produced greater acid suppression in the morning and at night with bid dosing than cimetidine with quid dosing. The knowledge that there is a circadian pattern in acid production, with higher levels between 10 PM and 2 AM, resulted in the development and use of a single evening dose of ranitidine. Ongoing research continues to investigate the effects of dose timing and the influence of more potent acid-suppressing agents. Finally, the issue of maintenance therapy and gastric acid secretion was addressed. The clinical advantage that ranitidine has over cimetidine in the prevention of ulcer recurrence can be attributed to its control of nocturnal acid suppression.

Gastric Acid↗
PubMed1978

The effect of highly selective vagotomy on the relationship between gastric mucosal blood flow and acid secretion in man.

Previous work has shown that the duodenal ulcer population can be defined by a lower ratio between gastric mucosal blood flow and acid secretion (during pentagastrin stimulation) than is found in normal subjects. The results of the present investigation have shown that the ratio is restored to normality by highly selective vagotomy. This suggests that increased tonic activity of the vagus on the parietal cell is one of the important disorders in duodenal ulceration.

Adult↗