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Drug Interactions between ethinyl estradiol / ethynodiol and tegaserod

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

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Interactions between your drugs

Minor

ethinyl estradiol tegaserod

Applies to: ethinyl estradiol / ethynodiol and tegaserod

Tegaserod decreased levonorgestrel plasma concentrations by less than 10% in a clinical study with a low-dose triphasic oral contraceptive (n=45). The mechanism is unknown. There were no changes in ethinyl estradiol concentrations or in contraceptive efficacy. No action is necessary.

References

  1. Vickers AE, Zollinger M, Dannecker R, Tynes R, Heitz F, Fischer V (2001) "In vitro metabolism of tegaserod in human liver and intestine: assessment of drug interactions." Drug Metab Dispos, 29, p. 1269-76
  2. (2002) "Product Information. Zelnorm (tegaserod)." Novartis Pharmaceuticals

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Drug and food interactions

Moderate

tegaserod food

Applies to: tegaserod

ADJUST DOSING INTERVAL: Food reduces the bioavailability of tegaserod by 40 to 65% and the maximum plasma concentration (Cmax) by 20 to 40%.

MANAGEMENT: Tegaserod should be taken before meals.

References

  1. (2002) "Product Information. Zelnorm (tegaserod)." Novartis Pharmaceuticals

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Minor

ethinyl estradiol food

Applies to: ethinyl estradiol / ethynodiol

Coadministration with grapefruit juice may increase the bioavailability of oral estrogens. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall induced by certain compounds present in grapefruits. In a small, randomized, crossover study, the administration of ethinyl estradiol with grapefruit juice (compared to herbal tea) increased peak plasma drug concentration (Cmax) by 37% and area under the concentration-time curve (AUC) by 28%. Based on these findings, grapefruit juice is unlikely to affect the overall safety profile of ethinyl estradiol. However, as with other drug interactions involving grapefruit juice, the pharmacokinetic alterations are subject to a high degree of interpatient variability. Also, the effect on other estrogens has not been studied.

References

  1. Weber A, Jager R, Borner A, et al. (1996) "Can grapefruit juice influence ethinyl estradiol bioavailability?" Contraception, 53, p. 41-7
  2. Schubert W, Eriksson U, Edgar B, Cullberg G, Hedner T (1995) "Flavonoids in grapefruit juice inhibit the in vitro hepatic metabolism of 17B-estradiol." Eur J Drug Metab Pharmacokinet, 20, p. 219-24

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Minor

ethinyl estradiol food

Applies to: ethinyl estradiol / ethynodiol

The central nervous system effects and blood levels of ethanol may be increased in patients taking oral contraceptives, although data are lacking and reports are contradictory. The mechanism may be due to enzyme inhibition. Consider counseling women about this interaction which is unpredictable.

References

  1. Hobbes J, Boutagy J, Shenfield GM (1985) "Interactions between ethanol and oral contraceptive steroids." Clin Pharmacol Ther, 38, p. 371-80

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Minor

ethynodiol food

Applies to: ethinyl estradiol / ethynodiol

The central nervous system effects and blood levels of ethanol may be increased in patients taking oral contraceptives, although data are lacking and reports are contradictory. The mechanism may be due to enzyme inhibition. Consider counseling women about this interaction which is unpredictable.

References

  1. Hobbes J, Boutagy J, Shenfield GM (1985) "Interactions between ethanol and oral contraceptive steroids." Clin Pharmacol Ther, 38, p. 371-80

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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

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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

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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