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Drug Interactions between Demulen and Ormazine

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

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Interactions between your drugs

Moderate

chlorproMAZINE ethinyl estradiol

Applies to: Ormazine (chlorpromazine) and Demulen (ethinyl estradiol / ethynodiol)

MONITOR: High chlorpromazine plasma concentrations and toxicity have been reported during concomitant use of an oral contraceptive. Chlorpromazine levels increased six-fold (from 134 ng/mL to 838 ng/mL) approximately one week after a patient started taking an ethinyl estradiol-norgestrel combination contraceptive, and she experienced tremors and severe dyskinesias. The mechanism is unknown but inhibition of CYP450 metabolism or effects on P-glycoprotein transport by contraceptive hormones have been suggested. Causality was not clearly determined.

MANAGEMENT: Until more information is available, monitoring for signs and symptoms of chlorpromazine toxicity when oral contraceptives are added to the regimen is recommended. Patients should be advised to notify their physician if they experience symptoms such as tremor, dyskinesias, or excessive sedation.

References

  1. Chetty M, Miller R (2001) "Oral contraceptives increase the plasma concentrations of chlorpromazine." Ther Drug Monit, 23, p. 556-8

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Drug and food interactions

Moderate

chlorproMAZINE food

Applies to: Ormazine (chlorpromazine)

GENERALLY AVOID: Concurrent use of ethanol and phenothiazines may result in additive CNS depression and psychomotor impairment. Also, ethanol may precipitate dystonic reactions in patients who are taking phenothiazines. The two drugs probably act on different sites in the brain, although the exact mechanism of the interaction is not known.

MANAGEMENT: Patients should be advised to avoid alcohol during phenothiazine therapy.

References

  1. Lutz EG (1976) "Neuroleptic-induced akathisia and dystonia triggered by alcohol." JAMA, 236, p. 2422-3
  2. Freed E (1981) "Alcohol-triggered-neuroleptic-induced tremor, rigidity and dystonia." Med J Aust, 2, p. 44-5

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Minor

ethinyl estradiol food

Applies to: Demulen (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: Demulen (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: Demulen (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.

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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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