Discontinue Daily Cialis Before Starting Levitra
Stop daily tadalafil (Cialis) at least 48 hours before initiating vardenafil (Levitra) therapy to avoid potential drug accumulation and enhanced hypotensive effects. 1
Rationale for the 48-Hour Washout Period
The 48-hour waiting period is based on tadalafil's extended half-life and duration of action compared to other PDE5 inhibitors:
- Tadalafil has a significantly longer half-life than vardenafil or sildenafil, requiring more time for complete drug clearance from the system 2
- ACC/AHA guidelines specifically state that nitrates are contraindicated within 48 hours of tadalafil use due to the risk of profound hypotension, MI, and even death—this same pharmacokinetic principle applies when switching between PDE5 inhibitors 1
- Overlapping PDE5 inhibitors could theoretically result in additive vasodilatory effects and increased risk of hypotension, though this specific interaction is not as well-studied as the nitrate interaction 1
Switching Strategy
When transitioning from daily tadalafil to vardenafil:
- Discontinue daily tadalafil and wait a minimum of 48 hours before the first dose of vardenafil 1
- Start vardenafil at standard dosing (typically 10 mg taken 25-60 minutes before sexual activity, adjustable to 5-20 mg based on efficacy and tolerability) 3
- Ensure proper patient education on vardenafil's pharmacologic profile: it should be taken in a fasted state for optimal absorption, as high-fat meals can delay efficacy 4, 5
- Avoid alcohol around the time of vardenafil use, as heavy alcohol impairs erectile function 4
Critical Safety Considerations
Before switching medications, verify the following:
- Confirm no concurrent nitrate use, as vardenafil is absolutely contraindicated with nitrates (though the exact safe interval for vardenafil after nitrate use has not been definitively established, blood pressure generally returns to baseline by 24 hours) 1
- Review cardiovascular risk status: high-risk cardiac patients (unstable angina, uncontrolled hypertension, recent MI/CVA, NYHA class II+ heart failure) should not receive ED treatment until stabilized 6, 7
- Check for alpha-blocker use, as concurrent use with PDE5 inhibitors requires caution due to additive hypotensive effects 2, 8
- Review CYP3A4 inhibitors/inducers in the patient's medication list, as these significantly affect PDE5 inhibitor plasma concentrations and may require dose adjustment 8
Why the Switch May Be Necessary
Common reasons for switching from tadalafil to vardenafil include:
- Incomplete response to daily tadalafil, though note that switching to a different PDE5 inhibitor can convert 25-40% of non-responders into responders 4, 5
- Side effect profile: vardenafil and avanafil have lower rates of myalgia compared to tadalafil 6
- Patient preference for on-demand rather than daily dosing 1
Common Pitfall to Avoid
Do not assume all PDE5 inhibitors are interchangeable without a washout period. While sildenafil and vardenafil have shorter half-lives (allowing same-day switching in theory), tadalafil's 48-hour window must be respected to minimize risk of additive effects and ensure accurate assessment of the new medication's efficacy 1, 2