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Drug Interactions between Detrol LA and Terbinex with Eco Formula

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

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Interactions between your drugs

Moderate

terbinafine tolterodine

Applies to: Terbinex with Eco Formula (hydroxypropyl chitosan / terbinafine topical) and Detrol LA (tolterodine)

Consumer information for this interaction is not currently available.

MONITOR: Coadministration with drugs that are inhibitors of CYP450 2D6 may increase the plasma concentrations of tolterodine, which is primarily metabolized by this isoenzyme in most patients (referred to as "extensive metabolizers") to an active metabolite that is equipotent to tolterodine. A subset of the population (about 7%) is devoid of CYP450 2D6 (referred to as "poor metabolizers" or PMs) and uses CYP450 3A4 to metabolize tolterodine to an inactive metabolite instead. In a study to assess this interaction, fluoxetine (a potent CYP450 2D6 inhibitor) was administered concurrently with immediate release tolterodine. It was observed that fluoxetine significantly inhibited the metabolism of tolterodine immediate release in extensive metabolizers, resulting in a 4.8-fold increase in tolterodine systemic exposure (AUC). There was a 52% decrease in the peak plasma concentration (Cmax) and a 20% decrease in the AUC of tolterodine's active metabolite. During this interaction the sums of unbound serum concentrations of tolterodine and its active metabolite are about 25% higher, meaning little alteration in the overall pharmacological activity of tolterodine is expected. However, increased plasma concentrations may increase the risk of adverse effects associated with tolterodine, including QT prolongation and anticholinergic effects.

MANAGEMENT: During concomitant therapy with drugs that inhibit CYP450 2D6 activity, the possibility of prolonged and/or increased pharmacologic effects of tolterodine should be considered. Increased monitoring may be particularly important when the CYP450 2D6 inhibitor has a similar adverse effect profile to that of tolterodine or when its inhibitory effects are long lasting (e.g., rolapitant can increase the plasma concentrations and risk of adverse effects of CYP450 2D6 substrates for at least 28 days). Patients should be counseled to report any increases in side effects or changes in condition.

References

  1. "Product Information. Detrol (tolterodine)." Pharmacia and Upjohn PROD (2001):
  2. Brynne N, Svanstrom C, AbergWistedt A, Hallen B, Bertilsson L "Fluoxetine inhibits the metabolism of tolterodin-pharmacokinetic implications and proposed clinical relevance." Br J Clin Pharmacol 48 (1999): 553-63
  3. "Product Information. Varubi (rolapitant)." Tesaro Inc. (2015):
  4. "Product Information. Tolterodine Tartrate ER (tolterodine)." Ajanta Pharma USA (2021):
  5. "Product Information. Tolterodine Tartrate (tolterodine)." Greenstone LLC (2014):
  6. "Product Information. Detrusitol XL (tolterodine)." Viatris UK Healthcare Ltd (2023):
View all 6 references

Drug and food interactions

No alcohol/food interactions were found. However, this does not necessarily mean no interactions exist. Always consult your healthcare provider.

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.