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Drug Interactions between Tracleer and Viagra

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

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Interactions between your drugs

Moderate

sildenafil bosentan

Applies to: Viagra (sildenafil) and Tracleer (bosentan)

MONITOR: Coadministration of bosentan and sildenafil may result in increased bosentan plasma concentrations and decreased sildenafil plasma concentrations. The mechanism is sildenafil inhibition of bosentan metabolism via CYP450 3A4 and 2C9, and bosentan induction of sildenafil metabolism via these same isoenzymes. In healthy subjects, coadministration of multiple doses of bosentan (125 mg twice a day) and sildenafil (80 mg three times a day) resulted in a 50% increase in bosentan systemic exposure (AUC) and a 63% reduction of sildenafil systemic exposure. Bosentan peak plasma concentration (Cmax) increased by 42% and sildenafil Cmax decreased by 55%. The combination did not lead to clinically significant changes in blood pressure, supine or standing.

MANAGEMENT: No dosage adjustment of either drug is necessary, whether sildenafil is used for the treatment of pulmonary arterial hypertension (PAH) or erectile dysfunction. However, adding sildenafil to bosentan therapy does not provide any beneficial effect on exercise capacity in the treatment of PAH. If prescribed together, the possibility of prolonged and/or increased pharmacologic effects of bosentan, including serious adverse effects such as hepatotoxicity, should be considered. Patients should be advised to seek medical attention if they experience signs and symptoms of hepatotoxicity such as fever, rash, anorexia, nausea, vomiting, fatigue, right upper quadrant pain, dark urine, and jaundice.

References

  1. (2001) "Product Information. Tracleer (bosentan)." Actelion Pharmaceuticals US Inc
  2. (2005) "Product Information. Revatio (sildenafil)." Pfizer U.S. Pharmaceuticals Group

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Drug and food interactions

Moderate

sildenafil food

Applies to: Viagra (sildenafil)

GENERALLY AVOID: Coadministration with grapefruit juice may slightly increase the oral bioavailability and delay the onset of action of sildenafil. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. In a randomized, crossover study with 24 healthy male volunteers, ingestion of 250 mL of grapefruit juice one hour before and concurrently with a 50 mg dose of sildenafil increased the mean area under the plasma concentration-time curve (AUC) of sildenafil and its pharmacologically active N-desmethyl metabolite by 23% and 24%, respectively, compared to water. Peak plasma concentrations (Cmax) were unaltered, but the time to reach sildenafil Cmax was prolonged by 0.25 hour. The observed increase in sildenafil bioavailability is unlikely to be of clinical significance in most individuals. However, pharmacokinetic interactions involving grapefruit juice are often subject to a high degree of interpatient variability and may be significant in the occasional susceptible patient. Indeed, one subject in the study had a 2.6-fold increase in sildenafil concentrations.

MANAGEMENT: It may be advisable to avoid administration of sildenafil with grapefruit juice to prevent potential toxicity and delay in onset of action.

References

  1. Jetter A, Kinzig-Schippers M, Walchner-Bonjean M, et al. (2002) "Effects of grapefruit juice on the pharmacokinetics of sildenafil." Clin Pharmacol Ther, 71, p. 21-29

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Therapeutic duplication warnings

Therapeutic duplication is the use of more than one medicine from the same drug category or therapeutic class to treat the same condition. This can be intentional in cases where drugs with similar actions are used together for demonstrated therapeutic benefit. It can also be unintentional in cases where a patient has been treated by more than one doctor, or had prescriptions filled at more than one pharmacy, and can have potentially adverse consequences.

Duplication

Agents for pulmonary hypertension

Therapeutic duplication

The recommended maximum number of medicines in the 'agents for pulmonary hypertension' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'agents for pulmonary hypertension' category:

  • Tracleer (bosentan)
  • Viagra (sildenafil)

Note: In certain circumstances, the benefits of taking this combination of drugs may outweigh any risks. Always consult your healthcare provider before making changes to your medications or dosage.

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

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

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