Cialis (Tadalafil) is a Vasodilator
Yes, Cialis (tadalafil) is a vasodilator that works by inhibiting phosphodiesterase type 5 (PDE5), which increases cGMP levels causing smooth muscle relaxation and vasodilation. 1, 2
Mechanism of Action
- Tadalafil inhibits PDE5, which normally hydrolyzes cyclic guanosine monophosphate (cGMP) 1
- By preventing cGMP degradation, tadalafil enhances and prolongs the vasodilating effects of nitric oxide 1
- This vasodilation effect is the primary mechanism for its therapeutic benefits in both erectile dysfunction and pulmonary hypertension 1
- PDE5 inhibitors like tadalafil are classified as mild systemic vasodilators 2
Clinical Evidence of Vasodilatory Effects
- Clinical pharmacology studies have demonstrated that tadalafil potentiates the hypotensive effect of nitrates, confirming its vasodilatory properties 2
- When combined with other vasodilators such as alpha-blockers or alcohol, tadalafil can produce additive blood pressure-lowering effects 2
- Small reductions in blood pressure occur following coadministration of tadalafil with antihypertensive medications (including amlodipine, angiotensin II receptor blockers, bendrofluazide, enalapril, and metoprolol) 2
- Chronic tadalafil administration has been shown to improve endothelium-dependent vasodilation of cavernous arteries in men with erectile dysfunction 3
Vasodilatory Applications
- Tadalafil's vasodilatory properties make it effective for treating erectile dysfunction by increasing blood flow to the penis 1, 4
- While sildenafil is FDA-approved for pulmonary arterial hypertension (PAH), tadalafil was also being studied for PAH treatment as of 2009 due to its vasodilatory effects 1
- The vasodilatory effects of tadalafil can last up to 36 hours, significantly longer than sildenafil, providing a wider therapeutic window 5, 6
Clinical Considerations Related to Vasodilation
- Due to its vasodilatory effects, tadalafil is contraindicated in patients taking any form of organic nitrates 2
- If nitrate administration becomes medically necessary in a life-threatening situation, at least 48 hours should elapse after the last dose of tadalafil 2
- Caution is advised when tadalafil is coadministered with alpha-blockers as both are vasodilators and can have additive effects on blood pressure 2
- Substantial alcohol consumption (≥5 units) in combination with tadalafil can increase orthostatic symptoms (increased heart rate, decreased standing blood pressure, dizziness, headache) due to their combined vasodilatory effects 2
Comparative Vasodilatory Effects
- Both sildenafil and tadalafil are PDE5 inhibitors with similar vasodilatory mechanisms, but tadalafil has a longer half-life of 17.5 hours compared to sildenafil 5, 6
- This longer half-life allows tadalafil to provide more sustained vasodilatory effects, potentially offering greater flexibility for sexual activity 5
Understanding tadalafil's role as a vasodilator is important for clinical decision-making, particularly regarding potential drug interactions and contraindications in patients with cardiovascular conditions.