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Drug Interactions between Enablex and posaconazole

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

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Interactions between your drugs

Major

darifenacin posaconazole

Applies to: Enablex (darifenacin) and posaconazole

ADJUST DOSE: Coadministration with potent inhibitors of CYP450 3A4 may significantly increase the plasma concentrations of darifenacin, which is partially metabolized by the isoenzyme. Darifenacin is also metabolized by CYP450 2D6, but 3A4 is the major pathway of metabolism in so-called poor metabolizers of 2D6 (approximately 7% of Caucasians and 2% of Asians and those of African descent). In a drug interaction study involving 10 extensive metabolizers and 1 poor metabolizer of 2D6, coadministration with the potent 3A4 inhibitor ketoconazole (400 mg) increased the mean steady-state peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of darifenacin (extended-release 7.5 mg once a day) approximately 5-fold each compared to values previously reported for extensive metabolizers of 2D6. In the poor metabolizer, Cmax and AUC of darifenacin increased approximately 13-fold each compared to values previously reported for poor metabolizers. When a 15 mg daily dose of extended-release darifenacin was given with ketoconazole, mean darifenacin Cmax and AUC in 3 extensive metabolizers increased approximately 12-fold compared to historical values, while Cmax and AUC increased approximately 6-fold in the poor metabolizer compared to historical values.

MANAGEMENT: The dosage of darifenacin should not exceed 7.5 mg/day when used with potent CYP450 3A4 inhibitors. Some authorities recommend avoiding concomitant use of darifenacin during and for 2 weeks after treatment with itraconazole.

References

  1. (2002) "Product Information. Sporanox (itraconazole)." Janssen Pharmaceuticals
  2. (2005) "Product Information. Enablex (darifenacin)." Novartis Pharmaceuticals
  3. Cerner Multum, Inc. "Australian Product Information."
  4. Niwa T, Shiraga T, Takagi A (2005) "Effect of antifungal drugs on cytochrome P450 (CYP) 2C9, CYP2C19, CYP3A4 activities in human liver microsomes." Biol Pharm Bull, 28, p. 1805-8
View all 4 references

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Drug and food interactions

Moderate

posaconazole food

Applies to: posaconazole

ADJUST DOSING INTERVAL: Food significantly increases the absorption of posaconazole from the oral suspension but only modestly from the delayed-release tablet. Following single-dose administration, posaconazole mean peak plasma concentration (Cmax) and systemic exposure (AUC) are approximately 2.5 to 3 times higher when the oral suspension is given with a nonfat meal or a nutritional supplement (14 grams of fat) than when given under fasting conditions, and approximately 3.5 to 4 times higher when given during or 20 minutes after a high-fat meal (50 grams of fat) than under fasting conditions. Acidic beverages may also increase posaconazole absorption. In 12 healthy volunteers, administration of a single 400 mg dose of posaconazole suspension with 12 ounces of ginger ale increased posaconazole Cmax by 92% and AUC by 70% compared to administration after fasting. In contrast, the Cmax and AUC of posaconazole increased by just 16% and 51%, respectively, when posaconazole tablets were given as a single 300 mg dose to healthy volunteers after a high-fat meal relative to a fasted state.

GENERALLY AVOID Concomitant use of alcohol and posaconazole administered in the form of delayed-release oral suspension may lead to a faster release of posaconazole. An in vitro dissolution study determined a potential for alcohol-induced dose-dumping with the delayed-release oral suspension of posaconazole.

MONITOR: In 5 study subjects, posaconazole Cmax decreased by 27% to 53% and AUC decreased by 33% to 51% when the oral suspension was administered via a nasogastric tube as opposed to orally.

MANAGEMENT: Posaconazole tablets should be taken with food, whereas posaconazole oral suspension should be administered during or immediately (i.e., within 20 minutes) following a full meal to enhance bioavailability. Patients who cannot eat a full meal should take the suspension with a liquid nutritional supplement or an acidic carbonated beverage such as ginger ale. In patients who cannot eat a full meal or tolerate an oral nutritional supplement or an acidic carbonated beverage and who do not have the option of taking another formulation of posaconazole, alternative antifungal therapy should be considered; otherwise, monitor patients closely for breakthrough fungal infections. Patients receiving posaconazole via a nasogastric tube should also be closely monitored due to increased risk of treatment failure associated with lower plasma exposure. Administration of alcohol with posaconazole from the delayed-release oral suspension formulation is not recommended.

References

  1. (2006) "Product Information. Noxafil (posaconazole)." Schering-Plough Corporation
  2. Sansone-Parsons A, Krishna G, Calzetta A, et al. (2006) "Effect of a nutritional supplement on posaconazole pharmacokinetics following oral administration to healthy volunteers." Antimicrob Agents Chemother, 50, p. 1881-3
  3. Krishna G, Moton A, Ma L, Malavade D, Medlock M, McLeod J (2008) "Effect of gastric pH, dosing regimen and prandial state, food and meal timing relative to dose, and gastro-intestinal motility on absorption and pharmacokinetics of the antifungal posaconazole." 18th European Congress of Clinical Microbiology and Infectious Diseases, April, p. 20
  4. Walravens J, Brouwers J, Spriet I, Tack J, Annaert P, Augustijns P (2011) "Effect of pH and Comedication on Gastrointestinal Absorption of Posaconazole: Monitoring of Intraluminal and Plasma Drug Concentrations." Clin Pharmacokinet, 50, p. 725-34
View all 4 references

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Minor

darifenacin food

Applies to: Enablex (darifenacin)

The consumption of grapefruit juice may be associated with increased plasma concentrations of darifenacin. The mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. The clinical significance is unknown.

References

  1. Cerner Multum, Inc. "UK Summary of Product Characteristics."

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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

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