Tadalafil
Tadalafil
Overview
Tadalafil (Cialis/Adcirca) is a long-acting PDE5 inhibitor FDA-approved for erectile dysfunction benign prostatic hyperplasia and pulmonary arterial hypertension. Its 17-36 hour half-life — dramatically longer than sildenafil's 4-5 hours — earned it the nickname 'the weekend pill' and enables a daily low-dose regimen that provides continuous ED treatment without on-demand timing. Tadalafil has become the preferred PDE5 inhibitor for daily use and has generated significant research interest for applications in heart failure muscle wasting and cancer biology beyond its approved indications.
Mechanism of Action
Tadalafil inhibits PDE5 through the same mechanism as sildenafil — preventing cGMP breakdown and prolonging smooth muscle relaxation in response to nitric oxide signaling. Its superior selectivity for PDE5 over PDE6 (retinal) and PDE11 (testicular/cardiac) gives it a cleaner side effect profile than sildenafil with less visual disturbance and better tolerability. The extended half-life results from tadalafil's highly lipophilic structure which increases tissue distribution and slows elimination. Daily low-dose tadalafil (2.5-5mg) maintains continuous penile smooth muscle relaxation improving erectile function with less on-demand planning. Recent research has identified potential muscle-preserving effects through PDE5 inhibition in skeletal muscle and cardioprotective effects through improved cardiac cGMP signaling.
Dosage Information
Typical Dose
5-20 mg as needed or 2.5-5 mg daily
Frequency
As needed (at least 30 minutes before activity) or once daily
Administration
Oral tablet
Notes
Daily dosing (2.5-5mg) eliminates need for timing before sexual activity. Food does not affect absorption unlike sildenafil. Absolute contraindication with nitrates.
Where does Tadalafil sit?
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Evidence Score
0.75
Compound Data
Molecular Formula
C22H19N3O4
Molecular Weight
389.40 g/mol
IUPAC Name
(2R,8R)-2-(1,3-benzodioxol-5-yl)-6-methyl-3,6,17-triazatetracyclo[8.7.0.03,8.011,16]heptadeca-1(10),11,13,15-tetraene-4,7-dione
PubChem CID
110635Potential Side Effects
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Quick Facts
- Administration
- Oral tablet
- Typical Dose
- 5-20 mg as needed or 2.5-5 mg daily
- Frequency
- As needed (at least 30 minutes before activity) or once daily
- References
- 0 curated + 48 from PubMed
- Clinical Trials
- 41 registered
- Evidence Score
- 0.8 / 100