Tadalafil (Pulmonary Arterial Hypertension)
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 BRAND NAMES
 MECHANISM OF ACTION
Tadalafil is a selective inhibitor of phosphodiesterase type 5 (PDE5), the enzyme responsible for the degradation of cyclic guanosine monophosphate (cGMP). PDE5 is found in pulmonary vascular smooth muscle.
Pulmonary arterial hypertension is associated with impaired release of nitric oxide by the vascular endothelium and consequent reduction of cGMP concentrations in the pulmonary vascular smooth muscle. PDE5 is the predominant phosphodiesterase in the pulmonary vasculature. Inhibition of PDE5 by tadalafil increases the concentrations of cGMP resulting in relaxation of pulmonary vascular smooth muscle cells and vasodilation of the pulmonary vascular bed.
Treatment of pulmonary arterial hypertension to improve exercise ability
 DOSAGE FORMS AND STRENGTHS
Tablets (not scored): 20 mg
40 mg once daily, with or without food. Dividing the dose (40 mg) over the course of the day is not recommended.
- Concomitant organic nitrates (4.1)
- History of known serious hypersensitivity reaction to ADCIRCA or CIALIS
- Cardiovascular effects: Carefully consider whether patients with certain underlying conditions (e.g., cardiovascular disease, impaired autonomic control of blood pressure, aortic stenosis) could be adversely affected by vasodilatory effects of ADCIRCA. Not recommended in patients with pulmonary veno-occlusive disease
- Effects on the eye: Patients should seek immediate medical attention if sudden loss of vision occurs, which could be a sign of non-arteritic ischemic optic neuropathy (NAION).
- Hearing impairment: Advise patients to seek immediate medical attention if sudden decrease or loss of hearing occurs
- Prolonged erection: Advise patients to seek emergency treatment if an erection lasts >4 hours.
- Use with ritonavir requires dosage adjustments.
- Potent CYP3A inhibitors A such as ketoconazole and itraconazole: Avoid use with ADCIRCA.
- Potent Inducers of CYP3A: Avoid use of ADCIRCA in patients chronically taking potent inducers of CYP3A (e.g., rifampin).
- Concomitant PDE5 inhibitors: Avoid use with CIALIS or other PDE5 inhibitors
- Concomitant alpha-blockers or alcohol: Note additive blood pressure-lowering effects
 PREGNANCY AND LACTATION
 SIDE EFFECTS
The most common adverse reaction is headache