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Drug Interactions between clonazepam and ethinyl estradiol / norelgestromin

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

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Interactions between your drugs

Minor

clonazePAM ethinyl estradiol

Applies to: clonazepam and ethinyl estradiol / norelgestromin

Oral contraceptives may prolong the half-life of certain benzodiazepines that undergo hepatic oxidative metabolism (such as diazepam and chlordiazepoxide). Other benzodiazepines also may participate in this interaction. Close observation for signs and symptoms of altered benzodiazepine effect is recommended.

References (4)
  1. Patwardhan RV, Mitchell MC, Johnson RF, Schenker S (1983) "Differential effects of oral contraceptive steroids on the metabolism of benzodiazepines." Hepatology, 3, p. 248-53
  2. Stoehr GP, Kroboth PD, Juhl RP, Wender DB, Phillips JP, Smith RB (1984) "Effect of oral contraceptives on triazolam, temazepam, alprazolam, and lorazepam kinetics." Clin Pharmacol Ther, 36, p. 683-90
  3. Abernethy DR, Greenblatt DJ, Divoll M, Arendt R, Ochs HR, Shader RI (1982) "Impairment of diazepam metabolism by low-dose estrogen-containing oral-contraceptive steroids." N Engl J Med, 306, p. 791-2
  4. Scavone JM, Greenblatt DJ, Locniskar A, Shader RI (1988) "Alprazolam pharmacokinetics in women on low-dose oral contraceptives." J Clin Pharmacol, 28, p. 454-7

Drug and food interactions

Moderate

clonazePAM food

Applies to: clonazepam

GENERALLY AVOID: Acute ethanol ingestion may potentiate the CNS effects of many benzodiazepines. Tolerance may develop with chronic ethanol use. The mechanism may be decreased clearance of the benzodiazepines because of CYP450 hepatic enzyme inhibition. Also, it has been suggested that the cognitive deficits induced by benzodiazepines may be increased in patients who chronically consume large amounts of alcohol.

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

References (7)
  1. MacLeod SM, Giles HG, Patzalek G, Thiessen JJ, Sellers EM (1977) "Diazepam actions and plasma concentrations following ethanol ingestion." Eur J Clin Pharmacol, 11, p. 345-9
  2. Whiting B, Lawrence JR, Skellern GG, Meier J (1979) "Effect of acute alcohol intoxication on the metabolism and plasma kinetics of chlordiazepoxide." Br J Clin Pharmacol, 7, p. 95-100
  3. Divoll M, Greenblatt DJ, Lacasse Y, Shader RI (1981) "Benzodiazepine overdosage: plasma concentrations and clinical outcome." Psychopharmacology (Berl), 73, p. 381-3
  4. Juhl RP, Van Thiel DH, Dittert LW, Smith RB (1984) "Alprazolam pharmacokinetics in alcoholic liver disease." J Clin Pharmacol, 24, p. 113-9
  5. Ochs HR, Greenblatt DJ, Arendt RM, Hubbel W, Shader RI (1984) "Pharmacokinetic noninteraction of triazolam and ethanol." J Clin Psychopharmacol, 4, p. 106-7
  6. Staak M, Raff G, Nusser W (1979) "Pharmacopsychological investigations concerning the combined effects of dipotassium clorazepate and ethanol." Int J Clin Pharmacol Biopharm, 17, p. 205-12
  7. Nichols JM, Martin F, Kirkby KC (1993) "A comparison of the effect of lorazepam on memory in heavy and low social drinkers." Psychopharmacology (Berl), 112, p. 475-82
Moderate

ethinyl estradiol food

Applies to: ethinyl estradiol / norelgestromin

MONITOR: Coadministration of ethinyl estradiol may increase the plasma concentrations of drugs that are primarily metabolized by CYP450 1A2. In a study of 30 healthy volunteers administered the CYP450 1A2 substrate tizanidine, the systemic exposure (AUC) of tizanidine was 3.9 times greater in women using an oral contraceptive containing ethinyl estradiol.

MANAGEMENT: Patients should be monitored for increased adverse effects of the CYP450 1A2 substrate during concomitant use with ethinyl estradiol. Product labeling for the specific CYP450 1A2 substrate should be consulted for additional recommendations.

References (1)
  1. Granfors MT, Backman JT, Laitila J, Neuvonen PJ (2005) "Oral contraceptives containing ethinyl estradiol and gestodene markedly increase plasma concentrations and effects of tizanidine by inhibiting cytochrome P450 1A2." Clin Pharmacol Ther, 78, p. 400-11
Minor

ethinyl estradiol food

Applies to: ethinyl estradiol / norelgestromin

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 (2)
  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
Minor

ethinyl estradiol food

Applies to: ethinyl estradiol / norelgestromin

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

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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