Increased Blood Ethanol Levels Following Cimetidine but Not Ranitidine

Seitz, H.K.; Bösche, J; Czygan, P.; Veith, S.; Simon, Bernd; Kommereli, Burkhard

doi:10.1016/s0140-6736(83)92043-3

Cited by 27 publications

(12 citation statements)

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“…No significant alteration in the elimination rate of ethanol was observed. Seitz et al (1983) reported an increase in peak ethanol concentration (in 8 male subjects from 73.0 to 85.9 mg/dl and in AVC from 304 to 350 mg/dl· h) after cimetidine 1 g/day.…”

Section: Ethanolmentioning

confidence: 92%

Pharmacokinetic Interactions of Cimetidine 1987

Somogyi

Muirhead

1987

Clinical Pharmacokinetics

185

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The number of studies on drug interactions with cimetidine has increased at a rapid rate over the past 5 years, with many of the interactions being solely pharmacokinetic in origin. Very few studies have investigated the clinical relevance of such pharmacokinetic interactions by measuring pharmacodynamic responses or clinical endpoints. Apart from pharmacokinetic studies, invariably conducted in young, healthy subjects, there have been a large number of in vitro and in vivo animal studies, case reports, clinical observations and general reviews on the subject, which is tending to develop an industry of its own accord. Nevertheless, where specific mechanisms have been considered, these have undoubtedly increased our knowledge on the way in which humans eliminate xenobiotics. There is now sufficient information to predict the likelihood of a pharmacokinetic drug-drug interaction with cimetidine and to make specific clinical recommendations. Pharmacokinetic drug interactions with cimetidine occur at the sites of gastrointestinal absorption and elimination including metabolism and excretion. Cimetidine has been found to reduce the plasma concentrations of ketoconazole, indomethacin and chlorpromazine by reducing their absorption. In the case of ketoconazole the interaction was clinically important. Cimetidine does not inhibit conjugation mechanisms including glucuronidation, sulphation and acetylation, or deacetylation or ethanol dehydrogenation. It binds to the haem portion of cytochrome P-450 and is thus an inhibitor of phase I drug metabolism (i.e. hydroxylation, dealkylation). Although generally recognised as a nonspecific inhibitor of this type of metabolism, cimetidine does demonstrate some degree of specificity. To date, theophylline 8-oxidation, tolbutamide hydroxylation, ibuprofen hydroxylation, misonidazole demethylation, carbamazepine epoxidation, mexiletine oxidation and steroid hydroxylation have not been shown to be inhibited by cimetidine in humans but the metabolism of at least 30 other drugs is affected. Recent evidence indicates negligible effects of cimetidine on liver blood flow. Cimetidine reduces the renal clearance of drugs which are organic cations, by competing for active tubular secretion in the proximal tubule of the kidney, reducing the renal clearances of procainamide, ranitidine, triamterene, metformin, flecainide and the active metabolite N-acetylprocainamide. This previously unrecognised form of drug interaction with cimetidine may be clinically important for both parent drug, and metabolites which may be active.(ABSTRACT TRUNCATED AT 400 WORDS)

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Section: Ethanolmentioning

confidence: 92%

Pharmacokinetic Interactions of Cimetidine 1987

Somogyi

Muirhead

1987

Clinical Pharmacokinetics

185

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“…mono-oxygenase system in the liver and inhibits microsomal drug metabolism. Seitz et al (1983) studied the effect of ranitidine on ethanol disposition in 8 male volunteers who received a 20% v/v ethanol solution (0.8 g/kg body-502 weight) after pretreatment with ranitidine 300 mg/ day or placebo for 7 days. Neither peak plasma concentrations nor the AVC of ethanol were affected by ranitidine administration.…”

Section: Fentanylmentioning

confidence: 99%

Interactions and Non-Interactions with Ranitidine

Kirch

Hoensch

Janisch

1984

Clinical Pharmacokinetics

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At present, there are two H2-receptor antagonists available for the treatment of peptic ulcer disease - cimetidine and ranitidine. Cimetidine is well known to interact with a number of concurrently administered drugs. Like cimetidine, ranitidine binds to cytochrome P-450 in the liver where it appears to exert an inhibitory effect, but to a lesser extent than cimetidine. Both H2-receptor antagonists may also reduce hepatic blood flow. Several drugs which are known to interact with cimetidine have been found not to interact significantly with ranitidine, including propranolol, lignocaine, phenytoin and diazepam. However, significant pharmacokinetic interactions between ranitidine and several other drugs have been established. These interactions may be attributed variously to an effect of ranitidine on hepatic metabolism or to an effect on the absorption of concomitantly administered drugs. For example, the bioavailability of midazolam is significantly increased due to the influence of ranitidine on gastric pH and thus on absorption of midazolam, leading to an increased soporific effect of this benzodiazepine; an effect of ranitidine on oxidative liver metabolism also appears to be a contributory factor in this interaction. Conversely, ranitidine distinctly reduced protein-bound cobalamin absorption from a mean of 7.66% prior to ranitidine administration to 0.84% during treatment with ranitidine 300 mg daily. A significant pharmacokinetic interaction has also been demonstrated between ranitidine and procainamide: the AUC of procainamide increased and the renal clearance fell significantly from a mean of 378 to 309 ml/min with ranitidine co-administration. However, this interaction is due to a different mechanism. In this case, ranitidine appears to compete with procainamide for the common renal proximal tubular secretion site. The reported interactions of ranitidine with warfarin, metoprolol, nifedipine, theophylline and fentanyl appear to be due to inhibition of cytochrome P-450. In a clinical study, warfarin clearance was significantly reduced from 66.7 to 48.7 ml/min by ranitidine, and by cimetidine to 42.9 ml/min. Similarly, the elimination half-lives of metoprolol and nifedipine were distinctly prolonged and the AUCs significantly increased by ranitidine. However, the latter pharmacokinetic interactions appear unlikely to be of clinical significance since the clinical effects of metoprolol and nifedipine were unaffected by ranitidine treatment. In therapeutic concentrations, ranitidine inhibited the disappearance of fentanyl from an in vitro microsomal preparation, indicating that it inhibits microsomal drug metabolism.(ABSTRACT TRUNCATED AT 400 WORDS)

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“…A 7-day pretreatment with ranitidine did not alter the peak plasma alcohol concentration, AUC or elimination rate following a single oral dose of alcohol (Dobrilla et al 1984;Seitz et al 1983). Similar results were observed by Holtzman et al (1985) during long term ethanol consumption.…”

Section: Alcoholmentioning

confidence: 78%

Side Effects of Ranitidine

et al. 1991

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Ranitidine was first marketed in 1981; since then many patients have been treated such that much experience has been accumulated on the safety of this histamine H2-receptor antagonist in the treatment of gastroduodenal disease. A wide array of ranitidine-associated side effects has been described, but infrequently. As so much information is now available, the aim of this review is to assess the weight of evidence for a causal link between ranitidine and the reported side effects. Overall, ranitidine is well tolerated. The incidence of general side effects at less than 2% is very similar to placebo. Headaches, tiredness, dizziness and mild gastrointestinal disturbance (e.g. diarrhoea, constipation and nausea) are among the most frequent complaints, but have very seldom resulted in stopping treatment. Cardiovascular side effects are extremely rare and unpredictable with the usual doses of oral ranitidine (at most 1 in 1 million patients). They mostly comprise sinusal bradycardia and atrioventricular blockade, especially after rapid intravenous administration, receding after cessation of the drug. Clinical studies, however, have not shown a significant pharmacological effect of ranitidine on the cardiovascular system via H2-receptors, even though individual sensitivities cannot be ruled out in a few isolated reports. Ranitidine is unlikely to be directly hepatotoxic: a transient change in liver function tests has been noted in only 1 in 100 to 1 in 1000 patients. Several cases of mixed hepatitis have been reported, but very few were fully documented. The incidence of ranitidine-associated acute hepatitis has been estimated to be less than 1 in 100,000 patients. Neuropsychiatric complications may be less common and clinically quite similar to those reported with cimetidine, i.e. confusion, disorientation, hallucinations, delirium. These side effects have occurred especially in critically ill and multiple-therapy patients, or patients with chronic renal or hepatic failure, so that the direct causal link with ranitidine treatment was often difficult to ascertain. Even though an H2-receptor-mediated effect is an attractive hypothesis (since similar complications were noted with other H2-receptor antagonists), other mechanisms have been suggested to play a role, e.g. cholinergic or histaminic effects. The overall incidence of neuropsychiatric complications is probably markedly less than 1%. White cell injury (i.e. agranulocytosis) appears to be the most frequent haematological complication, even though case reports are very few and poorly documented.(ABSTRACT TRUNCATED AT 400 WORDS)

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Increased Blood Ethanol Levels Following Cimetidine but Not Ranitidine

Cited by 27 publications

References 0 publications

Pharmacokinetic Interactions of Cimetidine 1987

Pharmacokinetic Interactions of Cimetidine 1987

Interactions and Non-Interactions with Ranitidine

Side Effects of Ranitidine

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