Description

Simple

A medication used to treat erectile dysfunction, an enlarged prostate, and high blood pressure.

Clinical

A phosphodiesterase 5 inhibitor used to treat erectile dysfunction, benign prostatic hyperplasia, and pulmonary arterial hypertension.

Overview

Tadalafil is an orally administered drug used to treat male erectile dysfunction (impotence). It is marketed worldwide under the brand name Cialis. It is a phosphodiesterase 5 (PDE5) inhibitor. Tadalafil's distinguishing pharmacologic feature is its longer half-life (17.5 hours) compared with Viagra and Levitra (4-5 hours). This longer half-life results in a longer duration of action and is, in part, responsible for the Cialis nickname of the "weekend pill." This longer half-life also is the basis of current investigation for tadalafil's use in pulmonary arterial hypertension as a once-daily therapy.

Pharmacology

Indication

Used for the treatment of erectile dysfunction.

Pharmacodynamic

Tadalafil is used to treat male erectile dysfunction (impotence) and pulmonary arterial hypertension (PAH). Part of the physiological process of erection involves the release of nitric oxide (NO) in the corpus cavernosum. This then activates the enzyme guanylate cyclase which results in increased le... Read more

Mechanism of action

Penile erection during sexual stimulation is achieved by the relaxation of penile arteries and corpus cavernosal smooth muscles, leading to increased blood flow to the organ. This response is mediated by the release of nitric oxide (NO) from nerve terminals and endothelial cells, which stimulates th... Read more

Absorption

After single oral-dose administration, the maximum observed plasma concentration (Cmax) of tadalafil is achieved between 30 minutes and 6 hours (median time of 2 hours). Absolute bioavailability of tadalafil following oral dosing has not been determined.

Protein binding

94%

Volume of distribution

63 L

Clearance

oral cl=2.5 L/hr

Half life

17.5 hours

Route of elimination

Tadalafil is excreted predominantly as metabolites, mainly in the feces (approximately 61% of the dose) and to a lesser extent in the urine (approximately 36% of the dose).

Toxicity

Oral, Rat LD50 = 2000 mg/kg, no deaths or toxicity.

Adverse Effects

Contraindications

  • Regions: US
  • With Categories Coadmin:
      • Name: Organic Nitrates
      • Drugbank Id: DBCAT002456

Food Interactions

    Information currently not available.

Interactions

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  • Paracetamol(acetaminophen)
  • Paxil(paroxetine)
  • Pamelor(nortriptyline)
  • Panadol(acetaminophen)
  • Patanol(olopatadine ophthalmic)
  • Pataday(olopatadine ophthalmic)
  • Parnate(tranylcypromine)
  • Pazeo(olopatadine ophthalmic)
1-benzylimidazole
1-benzylimidazole may decrease the antihypertensive activities of Tadalafil.
2,5-Dimethoxy-4-ethylamphetamine
2,5-Dimethoxy-4-ethylamphetamine may decrease the antihypertensive activities of Tadalafil.
2,5-Dimethoxy-4-ethylthioamphetamine
2,5-Dimethoxy-4-ethylthioamphetamine may decrease the antihypertensive activities of Tadalafil.
4-Bromo-2,5-dimethoxyamphetamine
4-Bromo-2,5-dimethoxyamphetamine may decrease the antihypertensive activities of Tadalafil.
4-Methoxyamphetamine
4-Methoxyamphetamine may decrease the antihypertensive activities of Tadalafil.
5-methoxy-N,N-dimethyltryptamine
5-methoxy-N,N-dimethyltryptamine may decrease the antihypertensive activities of Tadalafil.
7,8-Dichloro-1,2,3,4-tetrahydroisoquinoline
7,8-Dichloro-1,2,3,4-tetrahydroisoquinoline may increase the hypotensive activities of Tadalafil.
Abacavir
Tadalafil may decrease the excretion rate of Abacavir which could result in a higher serum level.
Abatacept
The metabolism of Tadalafil can be increased when combined with Abatacept.
Abediterol
Abediterol may decrease the antihypertensive activities of Tadalafil.
Acalabrutinib
The metabolism of Tadalafil can be decreased when combined with Acalabrutinib.
Acarbose
Acarbose may decrease the excretion rate of Tadalafil which could result in a higher serum level.
Acebutolol
Tadalafil may increase the antihypertensive activities of Acebutolol.
Aceclofenac
Aceclofenac may decrease the excretion rate of Tadalafil which could result in a higher serum level.
Acemetacin
Acemetacin may decrease the excretion rate of Tadalafil which could result in a higher serum level.
Acepromazine
The risk or severity of hypotension, dyspepsia, and headache can be increased when Tadalafil is combined with Acepromazine.
Acetaminophen
Acetaminophen may decrease the excretion rate of Tadalafil which could result in a higher serum level.
Acetazolamide
Acetazolamide may increase the excretion rate of Tadalafil which could result in a lower serum level and potentially a reduction in efficacy.
Acetylsalicylic acid
Acetylsalicylic acid may decrease the excretion rate of Tadalafil which could result in a higher serum level.
Aclidinium
Tadalafil may decrease the excretion rate of Aclidinium which could result in a higher serum level.
3 References
  1. 1 . Naeije R, Huez S: Expert opinion on available options treating pulmonary arterial hypertension. Expert Opin Pharmacother. 2007 Oct;8(14):2247-65.PubMed: 17927481
  2. 2 . Burnett AL: Molecular pharmacotherapeutic targeting of PDE5 for preservation of penile health. J Androl. 2008 Jan-Feb;29(1):3-14. Epub 2007 Oct 17.PubMed: 17942972
  3. 3 . Guazzi M, Samaja M: The role of PDE5-inhibitors in cardiopulmonary disorders: from basic evidence to clinical development. Curr Med Chem. 2007;14(20):2181-91.PubMed: 17691956