Description
Tadalafil (Cialis) is a selective inhibitor of phosphodiesterase type 5 (PDE-5). The substance was developed by Lilly/ICOS and has been approved since 2003 for treatment of erectile dysfunction. Clinical approval extensions include pulmonary arterial hypertension (Adcirca) and benign prostatic hyperplasia.
Per study reports Tadalafil blocks PDE-5, the enzyme that breaks down cGMP in vascular smooth muscle. With higher cGMP, smooth muscle relaxes and blood flow increases - in the penile corpus cavernosum this results in erection-promoting action with sexual stimulation.
What distinguishes Tadalafil from Sildenafil is the substantially longer half-life of about 17.5 hours vs 3-5 hours for Sildenafil. Effectively this means an action window of up to 36 hours after a dose - referred to in research as the “weekend pill”. This decouples compound intake temporally from sexual activity, showing advantages in subject satisfaction in studies.
A second important property is food independence: unlike Sildenafil, Tadalafil’s action is not reduced by fatty meals. Bioavailability remains constant.
Known effects in studies: headache, back pain (often described), facial flushing, nasal congestion, in rare cases visual disturbances.
You can order Tadalafil as oral tablets in one bottle with 20mg per tablet.
This information is for research and educational purposes only. No medical recommendations.
Risks & Safety
Tadalafil sits in the mid range of the risk scale. As a PDE-5 inhibitor approved for over two decades the compound is well characterized, but one interaction is serious.
Documented in studies and the literature:
- Nitrate interaction: combination with nitrates or NO donors is contraindicated due to a massive blood pressure drop - the most serious of the known interactions.
- Headache and back pain: headache and the back-pain pattern typical of Tadalafil are frequently documented.
- Facial flushing and nasal congestion: flushing and nasal congestion are consistently documented as vasodilatory effects.
- Priapism risk: a prolonged painful erection is a documented rare risk of the PDE-5 inhibitor class.
- Visual disturbances: in rare cases visual disturbances are described in the studies.
Monitoring via bloodwork is recommended. This classification does not replace medical advice. Risk and responsibility for any actual use lie entirely with the buyer.
Studies
- Efficacy and Safety of Tadalafil for the Treatment of Erectile Dysfunction: Results of Integrated Analyses - Journal of Urology 2002, Brock et al: Integrated analysis of five RCTs, documents efficacy and a window of responsiveness up to 36 hours.
- Tadalafil Once Daily in Men with Erectile Dysfunction: An Integrated Analysis of Data Obtained from 1913 Patients - European Urology 2014, Porst et al: Integrated analysis of six RCTs on daily low-dose tadalafil 2.5mg and 5mg.
- The Clinical Pharmacokinetics of Phosphodiesterase-5 Inhibitors for Erectile Dysfunction - Journal of Clinical Pharmacology 2005, Gupta et al: Comparative review of the pharmacokinetic profile of all three PDE-5 inhibitors.
- Phosphodiesterase 5 Inhibitors for Erectile Dysfunction - Annals of Pharmacotherapy 2005, Setter et al: Direct class comparison of sildenafil, tadalafil and vardenafil.
