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Drug Interactions between conivaptan and emtricitabine / nelfinavir / tenofovir disoproxil

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

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Interactions between your drugs

Major

nelfinavir conivaptan

Applies to: emtricitabine / nelfinavir / tenofovir disoproxil and conivaptan

CONTRAINDICATED: Coadministration with potent inhibitors of CYP450 3A4 may significantly increase the plasma concentrations of vasopressin receptor antagonists conivaptan and tolvaptan, both of which are almost exclusively metabolized by the isoenzyme. According to the product labeling, administration of oral conivaptan 10 mg in combination with 200 mg of the potent CYP450 3A4 inhibitor ketoconazole resulted in 4- and 11-fold increases in conivaptan peak plasma concentration (Cmax) and systemic exposure (AUC), respectively, compared to administration alone. Similarly, when a single 30 mg oral dose of tolvaptan was administered to 19 healthy volunteers following pretreatment with ketoconazole 200 mg/day for 3 days, tolvaptan Cmax increased by 3.5-fold and AUC increased by 5.4-fold, although 24-hour urine output increased by just 1.3-fold due to the saturable nature of tolvaptan's effect on urinary excretion rate.

MANAGEMENT: Concomitant use of conivaptan or tolvaptan with potent CYP450 3A4 inhibitors is considered contraindicated. Some authorities recommend avoiding concomitant use of conivaptan or tolvaptan during and for 2 weeks after treatment with itraconazole.

References (4)
  1. (2002) "Product Information. Sporanox (itraconazole)." Janssen Pharmaceuticals
  2. (2006) "Product Information. Vaprisol (conivaptan)." Cumberland Pharmaceuticals Inc
  3. Cerner Multum, Inc. "Australian Product Information."
  4. (2009) "Product Information. Samsca (tolvaptan)." Otsuka American Pharmaceuticals Inc

Drug and food interactions

Minor

tenofovir food

Applies to: emtricitabine / nelfinavir / tenofovir disoproxil

Food enhances the oral absorption and bioavailability of tenofovir, the active entity of tenofovir disoproxil fumarate. According to the product labeling, administration of the drug following a high-fat meal increased the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of tenofovir by approximately 14% and 40%, respectively, compared to administration in the fasting state. However, administration with a light meal did not significantly affect the pharmacokinetics of tenofovir compared to administration in the fasting state. Food delays the time to reach tenofovir Cmax by approximately 1 hour. Tenofovir disoproxil fumarate may be administered without regard to meals.

References (1)
  1. (2001) "Product Information. Viread (tenofovir)." Gilead Sciences

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.