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Drug Interactions between Jalyn and lonafarnib

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

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Interactions between your drugs

Major

tamsulosin lonafarnib

Applies to: Jalyn (dutasteride / tamsulosin) and lonafarnib

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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Moderate

dutasteride lonafarnib

Applies to: Jalyn (dutasteride / tamsulosin) and lonafarnib

MONITOR: Based on in vitro data, coadministration with inhibitors of CYP450 3A4 may increase the plasma concentrations of dutasteride, which is metabolized by the isoenzyme. No clinical drug interaction studies have been conducted. However, a population pharmacokinetic analysis found decreased clearance of dutasteride when it is coadministered with the moderate CYP450 3A4 inhibitors, verapamil and diltiazem (37% and 44%, respectively). In contrast, no decrease in dutasteride clearance was seen during coadministration with amlodipine, a calcium channel blocker that is not a CYP450 3A4 inhibitor.

MANAGEMENT: The possibility of prolonged and/or increased pharmacologic effects of dutasteride should be considered during concomitant therapy with CYP450 3A4 inhibitors, particularly potent ones like itraconazole, ketoconazole, posaconazole, voriconazole, conivaptan, nefazodone, cobicistat, delavirdine, protease inhibitors, and ketolide and certain macrolide antibiotics.

References

  1. (2002) "Product Information. Duagen (dutasteride)." GlaxoSmithKline Healthcare

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Drug and food interactions

Major

lonafarnib food

Applies to: lonafarnib

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of lonafarnib. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Inhibition of hepatic CYP450 3A4 may also contribute. The interaction has not been studied with grapefruit juice, but has been reported for other CYP450 3A4 inhibitors. When a single 50 mg oral dose of lonafarnib was administered following pretreatment with the potent CYP450 3A4 inhibitor ketoconazole (200 mg once daily for 5 days) in healthy study subjects, lonafarnib peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 270% and 425%, respectively, compared to lonafarnib administered alone. In general, the effect of grapefruit juice is concentration-, dose- and preparation-dependent, and can vary widely among brands. Certain preparations of grapefruit juice (e.g., high dose, double strength) have sometimes demonstrated potent inhibition of CYP450 3A4, while other preparations (e.g., low dose, single strength) have typically demonstrated moderate inhibition. Increased exposure to lonafarnib may increase the risk and/or severity of adverse effects such as nausea, vomiting, diarrhea, anorexia, electrolyte disturbances, liver enzyme elevations, myelosuppression, infection, and hypertension.

ADJUST DOSING INTERVAL: Food does not have clinically relevant effects on the oral bioavailability of lonafarnib. When a single 75 mg oral dose of lonafarnib was administered with a high-fat meal (952 calories; approximately 43% from fat) in healthy subjects, lonafarnib Cmax and AUC decreased by 55% and 29%, respectively, compared to administration under fasted conditions. When administered with a low-fat meal (421 calories; approximately 12% from fat), lonafarnib Cmax decreased by 25% and AUC decreased by 21% relative to fasting. However, administration with food may help improve gastrointestinal tolerance to lonafarnib, which may commonly cause nausea, vomiting, diarrhea, and abdominal pain.

MANAGEMENT: Lonafarnib should be administered with the morning and evening meals and an adequate amount of water. Patients should avoid consumption of grapefruit or grapefruit juice and Seville oranges (also known as bitter or sour oranges).during treatment with lonafarnib.

References

  1. (2020) "Product Information. Zokinvy (lonafarnib)." Eiger BioPharmaceuticals

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Moderate

tamsulosin food

Applies to: Jalyn (dutasteride / 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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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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