Overview
11 DESCRIPTION Tadalafil is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). Tadalafil has the empirical formula C 22 H 19 N 3 O 4 representing a molecular weight of 389.41. The structural formula is: The chemical designation is 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-,...
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Penile erection during sexual stimulation is caused by increased penile blood flow resulting from the relaxation of penile arteries and corpus cavernosal smooth muscle. This response is mediated by the release of nitric oxide (NO) from nerve terminals and endothelial cells, which stimulates the synthesis of cGMP in smooth muscle cells. Cyclic GMP causes smooth muscle relaxation and increased blood flow into the corpus cavernosum. The inhibition of phosphodiesterase type 5 (PDE5) enhances erectile function by increasing the amount of cGMP. Tadalafil inhibits PDE5. Because sexual stimulation is required to initiate the local release of nitric oxide, the inhibition of PDE5 by tadalafil has no effect in the absence of sexual stimulation.
Indications
- 1 INDICATIONS AND USAGE Tadalafil is a phosphodiesterase 5 (PDE5) inhibitor indicated for the treatment of: erectile dysfunction (ED) ( 1.1 ) the signs and symptoms of benign prostatic hyperplasia (BPH) ( 1.2 ) ED and the signs and symptoms of BPH (ED/BPH) ( 1.3 ) If tadalafil is used with finasteride to initiate BPH treatment, such use is recommended for up to 26 weeks ( 1.4 ). 1.1 Erectile Dysfunction Tadalafil tablets are indicated for the treatment of erectile dysfunction (ED). 1.
Common Doses
- 10 mg
- 20 mg
- 5 mg
- 2.5 mg
Dosage
2 DOSAGE AND ADMINISTRATION Do not split tadalafil tablets; entire dose should be taken. Tadalafil tablets for use as needed: ED: Starting dose: 10 mg as needed prior to sexual activity. Increase to 20 mg or decrease to 5 mg based upon efficacy/tolerability. Improves erectile function compared to placebo up to 36 hours post dose. Not to be taken more than once per day ( 2.1 ). Tadalafil tablets for once daily use: ED: 2.5 mg taken once daily, without regard to timing of sexual activity. May increase to 5 mg based upon efficacy and tolerability ( 2.2 ).
Contraindications
- 4 CONTRAINDICATIONS Administration of tadalafil tablets to patients using any form of organic nitrate is contraindicated. Tadalafil was shown to potentiate the hypotensive effect of nitrates ( 4.1 ). History of known serious hypersensitivity reaction to tadalafil or ADCIRCA ® ( 4.2 ). Administration with guanylate cyclase (GC) stimulators, such as riociguat ( 4.3 ). 4.1 Nitrates Administration of tadalafil tablets to patients who are using any form of organic nitrate, either regularly and/or intermittently, is contraindicated.
Side Effects
- 6 ADVERSE REACTIONS Most common adverse reactions (≥2%) include headache, dyspepsia, back pain, myalgia, nasal congestion, flushing, and pain in limb ( 6.1 ). To report SUSPECTED ADVERSE REACTIONS, contact VKT Pharma Pvt. Ltd at 1 844-387-1231 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
Interactions
- 7 DRUG INTERACTIONS Tadalafil tablets can potentiate the hypotensive effects of nitrates, alpha-blockers, antihypertensives or alcohol ( 7.1 ). CYP3A4 inhibitors (e.g. ketoconazole, ritonavir) increase tadalafil exposure ( 2.7 , 5.10 , 7.2 ) requiring dose adjustment: Tadalafil tablets for use as needed: no more than 10 mg every 72 hours Tadalafil tablets for once daily use: dose not to exceed 2.5 mg CYP3A4 inducers (e.g. rifampin) decrease tadalafil exposure ( 7.2 ). 7.