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Drug Interaction Report

3 potential interactions and/or warnings found for the following 2 drugs:

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Interactions between your drugs

Moderate

clonazePAM voriconazole

Applies to: clonazepam, voriconazole

MONITOR: Coadministration with voriconazole may increase the plasma concentrations of drugs that are substrates of CYP450 2C19, 2C9, and/or 3A4. The mechanism is decreased clearance due to inhibition of those isoenzymes by voriconazole. Increased plasma levels and/or pharmacologic effects of drugs such as cyclosporine, sirolimus, tacrolimus (3A4 substrates), and warfarin (2C9 substrate) have been reported during coadministration with voriconazole.

MANAGEMENT: Caution is advised if voriconazole must be used concomitantly with medications that undergo metabolism by CYP450 2C19, 2C9 and/or 3A4, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever voriconazole is added to or withdrawn from therapy. The manufacturer specifically recommends that a dosage reduction be considered for benzodiazepines, statins, long-acting opiates, and vinca alkaloids that are metabolized by the affected isoenzymes when used with voriconazole.

References (3)
  1. (2002) "Product Information. VFEND (voriconazole)." Pfizer U.S. Pharmaceuticals
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  3. Cerner Multum, Inc. "Australian Product Information."

Drug and food interactions

Moderate

voriconazole food

Applies to: voriconazole

ADJUST DOSING INTERVAL: Food reduces the oral absorption and bioavailability of voriconazole. According to the product labeling, administration of multiple doses of voriconazole with high-fat meals decreased the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) by 34% and 24%, respectively, when the drug is administered as a tablet, and by 58% and 37%, respectively, when administered as the oral suspension.

MANAGEMENT: To ensure maximal oral absorption, voriconazole tablets and oral suspension should be taken at least one hour before or after a meal.

References (2)
  1. (2002) "Product Information. VFEND (voriconazole)." Pfizer U.S. Pharmaceuticals
  2. Wohlt PD, Zheng L, Gunderson S, Balzar SA, Johnson BD, Fish JT (2009) "Recommendations for the use of medications with continuous enteral nutrition." Am J Health Syst Pharm, 66, p. 1438-67
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

Therapeutic duplication warnings

No duplication 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.

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Further information

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

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