Drug Interactions between cimetidine and Naropin Polyamp
This report displays the potential drug interactions for the following 2 drugs:
- cimetidine
- Naropin Polyamp (ropivacaine)
Interactions between your drugs
cimetidine ROPivacaine
Applies to: cimetidine and Naropin Polyamp (ropivacaine)
Coadministration with inhibitors of CYP450 3A4 may modestly increase the plasma concentrations of ropivacaine. Although ropivacaine is primarily metabolized by CYP450 1A2, it has been shown to undergo some metabolism via CYP450 3A4. In eight healthy volunteers, pretreatment with the 3A4 inhibitor erythromycin (500 mg three times a day for 6 days) was found to have only minor effects on the pharmacokinetics of a single dose of ropivacaine (0.6 mg/kg IV over 30 minutes) compared to placebo. However, in combination with the potent 1A2 inhibitor fluvoxamine (100 mg daily), erythromycin further increased the area under the plasma concentration-time curve (AUC) of ropivacaine by 50% compared to fluvoxamine alone, which increased the ropivacaine AUC by 3.7-fold. Fluvoxamine alone prolonged the elimination half-life of ropivacaine from 2.3 to 7.4 hours, while the addition of erythromycin further increased the half-life to 11.9 hours. In another study, pretreatment with the potent 3A4 inhibitor ketoconazole (100 mg twice daily for 2 days) decreased the mean total plasma clearance of ropivacaine (40 mg IV over 20 minutes) by just 15% in 12 healthy volunteers. Thus, it appears that CYP450 3A4 inhibitors may only have a significant effect on the pharmacokinetics of ropivacaine in the presence of a CYP450 1A2 inhibitor such as fluvoxamine, ciprofloxacin, or mexiletine.
References
- Halldin MM, Bredberg E, Angelin B, Arvidsson T, Askemark Y, Elofsson S, Widman M (1996) "Metabolism and excretion of ropivacaine in humans." Drug Metab Dispos, 24, p. 962-8
- Oda Y, Furuichi K, Tanaka K, Hiroi T, Imaoka S, Asada A, Fujimori M, Funae Y (1995) "Metabolism of a new local anesthetic, ropivacaine, by human hepatic cytochrome P450." Anesthesiology, 82, p. 214-20
- (2001) "Product Information. Naropin (ropivacaine)." Astra-Zeneca Pharmaceuticals
- McClure JH (1996) "Ropivacaine." Br J Anaesth, 76, p. 300-7
- Ekstrom G, Gunnarsson UB (1996) "Ropivacaine, a new amide-type local anesthetic agent, is metabolized by cytochromes P450 1A and 3A in human liver microsomes." Drug Metab Dispos, 24, p. 955-61
- Arlander E, Ekstrom G, Alm C, Carrillo JA, Bielenstein M, Bottiger Y, Bertilsson L, Gustafsson LL (1998) "Metabolism of ropivacaine in humans is mediated by CYP1A2 and to a minor extent by CYP3A4: An interaction study with fluvoxamine and ketoconazole as in vivo inhibitors." Clin Pharmacol Ther, 64, p. 484-91
- Jokinen MJ, Ahonen J, Neuvonen PJ, Olkkola KT (2000) "The effect of erythromycin, fluvoxamine, and their combination on the pharmacokinetics of ropivacaine." Anesth Analg, 91, p. 1207-12
Drug and food interactions
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
- Feely J, Wood AJ (1982) "Effects of cimetidine on the elimination and actions of ethanol." JAMA, 247, p. 2819-21
- Hansten PD (1992) "Effects of H2-receptor antagonists on blood alcohol levels." JAMA, 267, p. 2469
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
- (2001) "Product Information. Tagamet (cimetidine)." SmithKline Beecham
- Broughton LJ, Rodgers HJ (1981) "Decreased systenuc clearance of caffeine due to cimetidine." Br J Clin Pharmacol, 12, p. 155-9
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
- 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.
See also
Report options
Drug Interaction Classification
| Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. | |
| Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. | |
| 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. | |
| No interaction information available. |
Further information
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