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Biomedical subjects

R Gugler

Publications and source records attributed to R Gugler.

At least 37 records · Page 2Linked to original sources
PubMed1990

Effects of antacids on the clinical pharmacokinetics of drugs. An update.

Since a previous review by Hurwitz was published in 1977 a large number of reports on drug interactions with antacids have appeared, few of which are of clinical relevance. Tetracyclines form insoluble complex molecules by metal ion chelation with various antacids; tetracycline absorption may be decreased by more than 90% by this interaction. Of the new class of quinolone antibiotics, the absorption of ciprofloxacin and ofloxacin is reduced by 50 to 90% in the presence of aluminium- and magnesium hydroxide-containing antacids. In contrast to early work showing inhibition of the absorption of beta-adrenergic blocking drugs by antacids, subsequent studies did not confirm a reduction in the bioavailability of either atenolol or propranolol during antacid treatment; indeed, they showed an increase in the plasma concentrations of metoprolol when the drug was coadministered with an antacid. The bioavailability of captopril was significantly reduced in the presence of an antacid, and lower plasma concentrations of this angiotensin-converting enzyme inhibitor were accompanied by a reduction of its effect on the systolic blood pressure of the patients. The absorption of the cardiac glycosides digoxin and digitoxin is not inhibited by antacids to a significant degree, although earlier studies had shown a positive effect when the dissolution of the glycoside preparations was relatively poor. Antacids reduce the bioavailability of the H2-receptor antagonists cimetidine and ranitidine only when high antacid doses are used and when the drugs are administered simultaneously. The bioavailability of famotidine was not significantly altered by a potent antacid preparation, although a trend towards reduced absorption was observed. Iron absorption is significantly decreased in the presence of sodium bicarbonate and calcium carbonate, but is nearly complete when coadministered with aluminium-magnesium hydroxide. Nonsteroidal anti-inflammatory drugs such as naproxen, tenoxicam, ketoprofen, ibuprofen and piroxicam are not affected in their absorption by antacid treatment. Theophylline bioavailability is unchanged when the drug is given together with antacids, although its rate of absorption may be altered, leading to a reduction or an increase in the time of the occurrence of peak plasma drug concentrations.

Adrenergic beta-Antagonists↗
PubMed1989

[Granulomatous colitis with pseudopolyp in schistosomiasis].

A 26-year-old Arab had epigastric pain and bloody mucous stools. At coloscopy distal proctitis and a polyp at the rectosigmoid junction were discovered. The polyp had granulomatous inflammatory changes and eggs of Schistosoma mansoni with a characteristic egg shell, central miracidium and lateral spine. Bilharziasis should be considered in the differential diagnosis of chronic inflammatory disease of the intestines.

Adult↗
PubMed1989

[The value of x-ray signs in the follow-up of Crohn's disease].

The value of various radiological signs in the follow-up of Crohn's disease has been studied in 175 radiological examinations of the gastro-intestinal tract in 39 patients. Changes in the significant radiological signs in Crohn's disease, such as spicula, cobblestone pattern, stenoses and fistulas, provide information on the development of the disease and on the effect of treatment. The signs have a prognostic significance only insofar as their persistence excludes any improvement. Radiological follow-up is particularly useful for spotting complications and for the early recognition of recurrences.

Adolescent↗
PubMed1989

[The course of Crohn disease and side effect profile with long-term treatment using metronidazole].

In a prospective study 21 patients with Crohn's disease not responding to standard treatment (salazosulfapyridine and/or corticosteroids) received metronidazole in a dose of 12 to 20 mg per kg body weight over 6 and 12 months respectively. The objectives were documentation of side effects and pharmacokinetic behaviour of metronidazole in relation to the course of the disease. In 3 months intervals and 3 months after the end of treatment activity indices were determined, the side effects of metronidazole were recorded and the drug plasma concentration was measured. Compliance of drug intake was excellent (94%). Best-Index decreased to a minimum after 6 months, orosomucoid after 3 months. Side effects from metronidazole (black tongue, dark urine, paraesthesia, metallic taste, epigastric pain, skin reactions, nausea) were reported by over 80% of the patients at any time of the study. Nearly 50% of patients developed paraesthesia, which was still present 3 months after the end of treatment. A mean dose of 15.4 mg per kg corresponded to a mean plasma concentration of 10.9 micrograms/ml of metronidazole. Plasma concentrations were not related to treatment success nor to the incidence of side effects. Treatment of Crohn's disease with metronidazole for longer than 3 months is not recommended both because of lack of additional therapeutic gain and because of the increasing risk of side effects.

Adolescent↗
PubMed1989

Effect of an aluminium-hydroxide containing antacid on the oral bioavailability of pirenzepine.

The effect of an antacid containing aluminium-hydroxide, magnesium-hydroxide and calcium carbonate (Trigastril) on the bioavailability of orally administered pirenzepine (Gastricur) was evaluated in 10 subjects in a double-blind single dose cross-over study. Pirenzepine was assayed in plasma by a highly sensitive high-performance liquid chromatographic method. A 2-compartment model was taken as a basis for the calculation of the plasma concentration curves and the pharmacokinetic parameters. The oral bioavailability of a 50 mg pirenzepine tablet concomitantly administered with 10 ml of the antacid gel preparation was slightly but not significantly greater than that of pirenzepine in the presence of a placebo gel. This was reflected by a mean increase of 18-28% in area under the curve (AUC 0-32, AUC 0-infinity, resp.) and of 26% in Cmax-values. There was no significant difference in the biological half-life of pirenzepine between the two treatments (10.1-9.4 h).

Administration, Oral↗
PubMed1987

Does smoking interfere with the effect of histamine H2-receptor antagonists on intragastric acidity in man?

The interaction between smoking and the effect of histamine H2-antagonists on intragastric acidity was examined in a double blind double dummy placebo controlled study. Healthy volunteers, 11 smokers and 10 non-smokers, were given, on four separate days at least one week apart, either placebo or cimetidine 800 mg nocte or ranitidine 2 X 150 mg per day or ranitidine 300 mg nocte. Tablets were taken at 2115 and 0900 h. Smokers smoked a cigarette hourly from 0700 to 2300 h. Breakfast, lunch, and dinner were standardised. Intragastric acidity was measured with a combined intragastric glass electrode and a solid state recorder. The subjects were fully ambulatory. The three histamine H2-receptor antagonist regimens were less effective (p = 0.04) in smokers than in non-smokers, but the difference between acidity of smokers and non-smokers was small. Means of medians of pH during a 24-h period with placebo, cimetidine 800 mg, ranitidine 2 X 150 mg and ranitidine 300 mg were 1.6, 2.3, 3.1, and 2.7 in smokers and 1.5, 2.7, 3.2, and 3.1 in non-smokers, respectively. In a second part of the study seven chronic smokers were reexamined after acutely stopping smoking: inhibition of gastric acidity by histamine H2-receptor antagonists was similar before and after withdrawal. Smoking does not affect intragastric acidity in untreated volunteers and only slightly decreases the effectiveness of histamine H2-receptor antagonists on intragastric acidity. This effect best in part explains the unfavourable effect of smoking on healing of peptic ulcer in patients treated with these drugs.

Adult↗
PubMed1987

[Inhibition of microsomal enzyme activity of the liver by various H2 receptor antagonists].

The inhibition of 7-ethoxycoumarin deethylase activity by four different H2-receptor antagonists was studied using rat liver microsomes. The compounds tested represent two classes of H2-antagonists, i. e. structures with (cimetidine and oxmetidine) and without (ranitidine and SKF 93479) an imidazole ring. The microsomes were prepared from untreated and phenobarbital-treated animals. It was found that all four compounds, even those without an imidazole ring, inhibited deethylase activity. The compounds inhibited in the following order: SKF 93479 (90%) greater than cimetidine (58%) = oxmetidine (58%) greater than ranitidine (23%). In microsomes from phenobarbital-induced animals, the inhibitory activity of oxmetidine was increased 5-fold. Only the inhibitory potency of cimetidine was increased by preincubation of the H2-antagonist with the microsomes prior to the addition of the substrate.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1986

Treatment of active duodenal ulcers with famotidine. A double-blind comparison with ranitidine.

In a double-blind multicenter trial, 100 patients with active duodenal ulcer were treated with a single nocturnal dose of famotidine 40 mg or ranitidine 300 mg. Antacid tablets were allowed as additional treatment if needed for pain relief. Endoscopy was repeated after two weeks, and again after four weeks if the ulcer had not healed earlier. Two patients in the famotidine group were withdrawn from the study because of non-compliance with the protocol. After two weeks, ulcers in 64 percent of the patients receiving famotidine and 46 percent of the patients receiving ranitidine were healed (p = 0.072). After four weeks, healing rates were 94 percent (famotidine) and 90 percent (ranitidine). Pain relief was rapid in either treatment group, with a tendency for better response during the day in the famotidine group. Mean antacid consumption during the first week was 3.0 tablets (34.5 mmol) in the famotidine group and 4.1 tablets (47.2 mmol) in the ranitidine group. Famotidine provides excellent healing and relief of symptoms in patients with duodenal ulcer disease.

Adult↗
PubMed1986

Inhibition of human liver cytochrome P-450 by omeprazole.

The effects of omeprazole on cytochrome P-450 mediated 7-ethoxycoumarin deethylation were studied in human liver microsomes. Omeprazole inhibited both the high and low affinity components of deethylation, with an estimated Ki of 0.03 mM for the high affinity component. The results are further evidence that the previously reported prolongation of the half-life of diazepam by omeprazole in vivo is due to inhibition of cytochrome P-450 monooxygenases.

7-Alkoxycoumarin O-Dealkylase↗