From the Guidelines
Tadalafil should be used with caution when taking dilantin due to potential interactions that may reduce its effectiveness or increase side effects. Taking tadalafil while on dilantin (phenytoin) requires careful medical supervision, as dilantin is a strong enzyme inducer that may significantly lower tadalafil levels in the bloodstream, potentially reducing its effectiveness for erectile dysfunction or other conditions 1. The combination of tadalafil and dilantin is not recommended, particularly given the higher side effect risk, as stated in the 2021 AUA guideline for the management of lower urinary tract symptoms attributed to benign prostatic hyperplasia 1.
Some key considerations when using tadalafil with dilantin include:
- Dilantin may increase the metabolism of tadalafil through the liver's cytochrome P450 3A4 enzyme system, causing the medication to be cleared from the body more quickly than intended
- The potential for reduced tadalafil effectiveness due to this interaction
- The need for potential dosage adjustments of tadalafil to compensate for this interaction
- The importance of monitoring for side effects like dizziness or blood pressure changes, given the impact of both medications on cardiovascular function
It is essential to consult a healthcare provider before taking tadalafil with dilantin, as they can provide personalized guidance and monitoring to ensure safe treatment 1.
From the Research
Tadalafil and Dilantin Interaction
- There are no direct studies on the interaction between tadalafil and Dilantin (phenytoin) in the provided evidence.
- However, it is known that Dilantin is a cytochrome P450 enzyme inducer, which can affect the metabolism of other drugs 2.
- Tadalafil is metabolized by cytochrome P450 enzymes, specifically CYP3A4 3, 4.
- Induction of CYP3A4 by Dilantin could potentially decrease the plasma concentrations of tadalafil, leading to reduced efficacy.
- On the other hand, some studies suggest that tadalafil can alter the activity of cytochrome P450 enzymes, including CYP3A4 4, 5.
- The clinical significance of these interactions is unclear, and more studies are needed to fully understand the potential effects of concomitant use of tadalafil and Dilantin.
- It is recommended to exercise caution when prescribing tadalafil to patients taking Dilantin, and to monitor for potential interactions and adjust the dosage as needed 2.