The syndrome of chronic pulmonary disease and gastroduodenal ulceration; a clinical study and literature review

Lack of influence of an intensive antacid regimen on theophylline bioavailability

We examined the influence of a large-volume, therapeutic antacid regimen, administered for three full days, on the steady-state bioavailability of a conventional-release and sustained-release theophylline product, Aminophyllin and Theodur, respectively. Nine stable asthmatics voluntarily completed a four-phase investigation requiring a total stay of 12 days in the Clinical Research Unit. The treatments consisted of administration of the formulations mentioned with and without antacids to each patient in a randomized sequence. Four patients participated in an additional phase where antacids were administered q2h around the clock for three days. After coadministration of theophylline plus antacids for two days, theophylline therapy was discontinued while numerous blood samples were obtained over 22 hr and analyzed for theophylline content via radioimmunoassay. Antacids had no predictable, consistent influence on theophylline absorption rate as determined by the absorption rate constant, the time to maximal theophylline concentration, or the lag time for theophylline absorption. Antacids had no detectable influence on theophylline elimination half-life and had no consistent, statistically significant effect on the extent of theophylline bioavailability, according to measurements of maximal concentration, AUC measured over the appropriate steady-state dosing interval, or elimination-rate adjusted AUC. The substantial intraindividual changes for all parameters of theophylline bioavailability that occurred for control and treatment phases likely represent spontaneous, random between-day variability in theophylline disposition independent of antacid administration, as evidenced by the comparability of the percent coefficient of variation for parameters of bioavailability across all phases. Our data demonstrate that therapeutic antacid administration has no effect on steady-state theophylline bioavailability and does not alter the intrinsic variability in theophylline absorption. Based on the results of our data, it is unlikely that a clinically significant (greater than 20%) decrease in theophylline absorption would occur in any patient treated intensively with antacids concurrently.

Effects of chronic hypoxia on canine gastric secretion

Interdigestive gastirc acid output and acid secretory response to histamine, insulin and pentagastrin were studied in five dogs before and after creation of a right to left extracardiac vascular shunt. The arterial PO2 decreased from 81.5 +/- 5.5 mm Hg to 39.8 +/- 6.0 mm Hg postoperatively with no change in arterial pH or PaCO2. Basal (interdigestive) acid output increased from 1.19 +/- 0.26 mEq/hr to 4.97 +/- 0.81 mEq/hr postoperatively. Acid secretory response to insulin was increased after the induction of chronic hypoxia. Increased sensitivity to pentagastric was also observed although parietal cell mass (maximum histamine-stimulated output) was unchanged postoperatively. Changes in acid secretory response and PaO2 were present at one week and were sustained through twelve weeks after shunting. Chronic hypoxia resulted in gastric acid hypersecretion secondary to enhanced sensitivity of the parietal cell to a combination of neural and humoral stimuli.

Effect of chronic hypercapnia on gastric secretion in the dog

Images