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Drug Interactions between tamsulosin and telaprevir

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

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Interactions between your drugs

Major

tamsulosin telaprevir

Applies to: tamsulosin and telaprevir

GENERALLY AVOID: Coadministration with potent inhibitors of CYP450 3A4 may significantly increase the plasma concentrations of tamsulosin, which is primarily metabolized by the hepatic microsomal isoenzymes CYP450 3A4 and 2D6. Severe hypotension and priapism may occur. In 24 healthy volunteers, administration of a single 0.4 mg dose of tamsulosin with the potent CYP450 3A4 inhibitor ketoconazole (400 mg once daily for 5 days) resulted in a 2.2-fold increase in tamsulosin peak plasma concentration (Cmax) and 2.8-fold increase in systemic exposure (AUC). The magnitude of interaction may be increased further in individuals who have genetic polymorphisms of CYP450 2D6 resulting in reduced or absent enzyme activity, or so-called CYP450 2D6 poor metabolizers (approximately 7% of Caucasians and less than 2% of Asians and individuals of African descent). When a single 0.4 mg dose of tamsulosin was given to 24 healthy volunteers with the potent CYP450 2D6 inhibitor paroxetine (20 mg once daily for 9 days), tamsulosin Cmax and AUC increased by a factor of 1.3 and 1.6, respectively. A similar increase in exposure is expected in CYP450 2D6 poor metabolizers as compared to extensive metabolizers, hence a potentially greater impact of CYP450 3A4 inhibition.

MANAGEMENT: Since CYP450 2D6 poor metabolizers cannot be readily identified, concomitant use of tamsulosin with potent CYP450 3A4 inhibitors should generally be avoided. Some authorities recommend avoiding concomitant use of tamsulosin during and for 2 weeks after treatment with itraconazole. If tamsulosin administration is discontinued for several days or more at either the 0.4 or 0.8 mg dose, therapy should be reinitiated with the 0.4 mg once-daily dose and titrated gradually as needed.

References

  1. (2002) "Product Information. Sporanox (itraconazole)." Janssen Pharmaceuticals
  2. (2001) "Product Information. Flomax (tamsulosin)." Boehringer-Ingelheim
  3. Cerner Multum, Inc. "Australian Product Information."
  4. Franco-Salinas G, de la Rosette JJ, Michel MC (2010) "Pharmacokinetics and pharmacodynamics of tamsulosin in its modified-release and oral controlled absorption system formulations." Clin Pharmacokinet, 49, p. 177-88
  5. Kamimura H, Oishi S, Matsushima H, et al. (1998) "Identification of cytochrome P450 isozymes involved in metabolism of the alpha1-adrenoceptor blocker tamsulosin in human liver microsomes." Xenobiotica, 28, p. 909-22
View all 5 references

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Drug and food interactions

Moderate

tamsulosin food

Applies to: tamsulosin

ADJUST DOSING INTERVAL: Food may delay the gastrointestinal absorption of tamsulosin. The time to maximum plasma concentration (Tmax) is reached by 4 to 5 hours under fasted conditions and by 6 to 7 hours when tamsulosin is administered with food. The delay in Tmax has the desirable effect of smoothing the tamsulosin plasma concentration profile, thereby reducing fluctuation of the plasma peak and trough concentrations with multiple dosing. Food may also affect the extent of absorption of tamsulosin. It has been reported that taking tamsulosin under fasted conditions results in a 30% increase in bioavailability (AUC) and 40% to 70% increase in peak plasma concentration (Cmax) compared to fed conditions. The effects of food on the pharmacokinetics of tamsulosin are consistent regardless of whether tamsulosin is taken with a light meal or a high-fat meal.

MANAGEMENT: To ensure uniformity of absorption, tamsulosin should be administered approximately one-half hour following the same meal each day.

References

  1. (2001) "Product Information. Flomax (tamsulosin)." Boehringer-Ingelheim

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Moderate

telaprevir food

Applies to: telaprevir

ADJUST DOSING INTERVAL: Food significantly enhances the oral bioavailability of telaprevir. When given with a meal containing 533 kcal and 21 g fat, telaprevir systemic exposure (AUC) increased by 237% compared to administration under fasting conditions. The type of meal also affects the exposure to telaprevir. Relative to fasting, telaprevir AUC increased by approximately 117% with a low-fat meal (249 kcal; 3.6 g fat) and 330% with a high-fat meal (928 kcal; 56 g fat). In Phase 3 clinical trials, telaprevir doses were administered within 30 minutes of completing a meal or snack containing approximately 20 grams of fat.

MANAGEMENT: Telaprevir should be administered with food containing approximately 20 grams of fat. Patients should be advised that the fat content of the meal or snack is critical to the absorption of telaprevir. Food taken with telaprevir should be ingested within 30 minutes prior to each dose. Examples of some foods that could be taken with telaprevir include: bagel with cream cheese; half cup of nuts; 3 tablespoons of peanut butter; 1 cup of ice cream; 2 ounces of American or cheddar cheese; 2 ounces of potato chips; or half cup of trail mix.

References

  1. (2011) "Product Information. Incivek (telaprevir)." Vertex Pharmaceuticals

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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

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