II. Indications

  1. Psychogenic Impotence
  2. Neurogenic Impotence
  3. Vasculogenic Impotence

III. Pharmacokinetics

  1. Onset within 30 to 60 minutes
  2. Duration as long as 36 hours
    1. Contrast with 4 hours with Viagra
    2. Prolonged effect also leads to prolonged side effects

IV. Dosing

  1. Start 20 mg PO 1 hour before intercourse
    1. Do not take more than once per 2 days
    2. Most insurance limits to 6 per month
  2. Indications to start with half dosing (10 mg)
    1. Age over 65 years
    2. Hepatic Impairment
    3. Renal Impairment
    4. Concurrent use of Cytochrome P3A4 inhibitor below

V. Contraindications

  1. See Phosphodiesterase Inhibitors (PDE5)
  2. Men using nitrates (causes profound Hypotension)
  3. Men using alpha blockers (e.g. Hytrin for BPH)

VI. Mechanism

VII. Drug Interactions

  1. See Phosphodiesterase Inhibitors (PDE5)
  2. Profound Vasodilitation and Hypotension with Nitroglycerin and alpha blockers such as Prazosin (Avoid)
  3. Cytochrome P3A4 related interactions (Cimetidine, systemic Antifungals, Protease Inhibitors and Macrolides

VIII. Adverse Effects: Viagra (but most apply to the PDE5 Class as a whole)

  1. See Phosphodiesterase Inhibitors (PDE5)
  2. Hypotensive effect for men on Nitrates (Avoid)
  3. Vision effects (color vision, Vision Loss)
  4. Sensorineural Hearing Loss
  5. Mild Headache (21%)

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Cost: Medications

cialis (on 6/7/2016 at Medicaid.Gov Survey of pharmacy drug pricing)
CIALIS 10 MG TABLET $49.75 each
CIALIS 2.5 MG TABLET $8.55 each
CIALIS 20 MG TABLET $49.79 each
CIALIS 5 MG TABLET $8.54 each

Ontology: Cialis (C0967376)

Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH C429886
SnomedCT 407112003
English cialis, Cialis (product), Cialis, Lilly brand of tadalafil
Spanish Cialis, Cialis (producto)

Ontology: tadalafil (C1176316)

Definition (NCI_NCI-GLOSS) A drug used to treat erectile dysfunction. It is also being studied in the treatment of sexual problems in patients treated with radiation or surgery for prostate cancer. Tadalafil blocks the action of a certain enzyme, which can result in increased blood flow to the penis, causing an erection. It is a type of cGMP phosphodiesterase type 5 (PDE5) inhibitor.
Definition (NCI) A carboline-based compound with vasodilatory activity. Tadalafil selectively inhibits the cyclic guanosine monophosphate (cGMP)-specific type 5 phosphodiesterase- (PDE-5)-mediated degradation of cGMP, which is found in the smooth muscle of the corpus cavernosa and corpus spongiosum of the penis. Inhibition of cGMP degradation by tadalafil results in prolonged muscle relaxation, vasodilation, and blood engorgement of the corpus cavernosa, and, so, prolonged penile erection.
Definition (PDQ) A carboline-based compound with vasodilatory properties. Tadalfil selectively inhibits the cyclic guanosine monophosphate (cGMP)-specific type 5 phosphodiesterase- (PDE-5)-mediated degradation of cGMP, which is found in the smooth muscle of the corpus cavernosa and corpus spongiosum of the penis. Inhibition of cGMP degradation by tadalfil results in prolonged muscle relaxation, vasodilation, and blood engorgement of the corpus cavernosa, and, so, prolonged penile erection. Check for "http://www.cancer.gov/Search/ClinicalTrialsLink.aspx?id=462366&idtype=1" active clinical trials or "http://www.cancer.gov/Search/ClinicalTrialsLink.aspx?id=462366&idtype=1&closed=1" closed clinical trials using this agent. ("http://nciterms.nci.nih.gov:80/NCIBrowser/ConceptReport.jsp?dictionary=NCI_Thesaurus&code=C47743" NCI Thesaurus)
Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH C429886
SnomedCT 407734006, 407111005
LNC LP100055-5, MTHU035872
English TADALAFIL @ @ UNIDENTIFIED, TADALAFIL UNIDENTIFIED, (6R,12aR)-2,3,6,7,12,12a-Hexahydro-2-methyl-6-(3,4-methylenedioxyphenyl)pyrazino(1',2':1,6)pyrido(3,4-b)indole-1,4-dione, tadalafil (medication), tadalafil [Chemical/Ingredient], TADALAFIL, tadalafil, Tadalafil (product), Tadalafil (substance), Tadalafil, Pyrazino(1',2':1,6)pyrido(3,4-b)indole-1,4-dione, 6-(1,3- benzodioxol-5-yl)-2,3,6,7,12,12a-hexahydro-2-methyl-, (6R,12aR)-
Spanish tadalafil (producto), tadalafil (sustancia), tadalafil