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Drug Interactions between Ethyol and Viagra

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

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Interactions between your drugs

Moderate

amifostine sildenafil

Applies to: Ethyol (amifostine) and Viagra (sildenafil)

MONITOR: Concomitant use with antihypertensive agents or drugs with hypotensive effects may increase the risk and severity of hypotension associated with amifostine. Hypotension has been reported frequently in patients treated with amifostine. It is usually transient (lasting from 5 to 15 minutes) and closely associated with amifostine administration, but may persist or become evident hours after administration. Moreover, hypotension can occur despite adequate hydration and positioning of the patient. Significant drops in systolic blood pressure have been reported, in some cases resulting in premature termination of amifostine infusion. In rare cases, sometimes during or after hypotension, patients have experienced tachycardia, bradycardia, dyspnea, apnea, hypoxia, chest pain, myocardial ischemia, renal failure, myocardial infarction, convulsions, unconsciousness, respiratory arrest, and cardiac arrest.

MANAGEMENT: If medically feasible, antihypertensive medications should be interrupted 24 hours prior to amifostine administration. Blood pressure should be closely monitored during and after treatment. In addition to hypotension, transient hypertension or exacerbation of preexisting hypertension may occur from intravenous hydration, discontinuation of antihypertensive medications, or other causes. Patients who continue their hypotensive medication(s) during amifostine therapy should be carefully monitored for the development of hypotension. Clinical symptoms of hypotension are usually quickly reversed by fluid infusion and postural management.

References

  1. "Product Information. Ethyol (amifostine)." Alza PROD (2001):
  2. "Product Information. Xatral (alfuzosin)." Sanofi-Synthelabo Canada Inc (2002):

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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. "Effects of grapefruit juice on the pharmacokinetics of sildenafil." Clin Pharmacol Ther 71 (2002): 21-29

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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.

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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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