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Drug Interactions between altretamine and cimetidine

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Moderate

cimetidine altretamine

Applies to: cimetidine and altretamine

GENERALLY AVOID: According to a rat model, the coadministration with cimetidine may increase the half-life and toxicity of altretamine. The likely mechanism is cimetidine inhibition of altretamine metabolism via CYP450 isoenzymes. In the study, 20 to 120 mg/kg of cimetidine (up to 114% of recommended human dose based on BSA) increased in a dose-related manner the half-life of altretamine by 29% to 80%. Cimetidine 120 mg/kg increased the toxicity of a single 350 mg/kg dose of altretamine from LD30 to LD75. In contrast, ranitidine had no significant effect on half-life or toxicity of altretamine.

MANAGEMENT: Based on animal data as well as human case reports of increased toxicity when other antineoplastic agents have been administered with cimetidine, the concomitant use of altretamine and cimetidine should generally be avoided if possible. Ranitidine may be a safer alternative if H2-antagonist therapy is necessary. Famotidine and nizatidine may also be considered, since they have not been shown to interfere with CYP450 metabolism.

References (2)
  1. (2022) "Product Information. Hexalen (altretamine)." US Bioscience
  2. Hande K, Combs G, Swingle R, Combs GL, Anthony L (1986) "Effect of cimetidine and ranitidine on the metabolism and toxicity of hexamethylmelamine." Cancer Treat Rep, 70, p. 1443-5

Drug and food interactions

Minor

cimetidine food

Applies to: cimetidine

Concurrent use of cimetidine and ethanol may result in increased ethanol concentrations. The mechanism appears to be due to inhibition of gastric alcohol dehydrogenase by cimetidine, leading to increased bioavailability of the alcohol and inhibition of hepatic metabolism of alcohol. The clinical significance of this interaction is limited. More importantly, patients requiring cimetidine for gastrointestinal disease should be counseled to avoid alcohol to prevent worsening of their disease. The other H-2 receptor antagonists appear to have minimal effects on the concentrations of alcohol.

References (2)
  1. Feely J, Wood AJ (1982) "Effects of cimetidine on the elimination and actions of ethanol." JAMA, 247, p. 2819-21
  2. Hansten PD (1992) "Effects of H2-receptor antagonists on blood alcohol levels." JAMA, 267, p. 2469
Minor

cimetidine food

Applies to: cimetidine

Caffeine effects may be increased in patients also taking cimetidine. The mechanism may be due to decreased caffeine metabolism induced by cimetidine. Although adequate clinical data are lacking, a reduction in dose or elimination of caffeine may be needed if excess CNS stimulation is observed.

References (2)
  1. (2001) "Product Information. Tagamet (cimetidine)." SmithKline Beecham
  2. Broughton LJ, Rodgers HJ (1981) "Decreased systenuc clearance of caffeine due to cimetidine." Br J Clin Pharmacol, 12, p. 155-9
Minor

cimetidine food

Applies to: cimetidine

H2 antagonists may reduce the clearance of nicotine. Cimetidine, 600 mg given twice a day for two days, reduced clearance of an intravenous nicotine dose by 30%. Ranitidine, 300 mg given twice a day for two days, reduced clearance by 10%. The clinical significance of this interaction is not known. Patients should be monitored for increased nicotine effects when using the patches or gum for smoking cessation and dosage adjustments should be made as appropriate.

References (1)
  1. Bendayan R, Sullivan JT, Shaw C, Frecker RC, Sellers EM (1990) "Effect of cimetidine and ranitidine on the hepatic and renal elimination of nicotine in humans." Eur J Clin Pharmacol, 38, p. 165-9

Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

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