Tadalafil

PDE5 5A 3 GAF/activation PKA, PKG cGMP Sildenafil, Vardenafil, Tadalafil,... 

Recent use (within 24 h of sildenafil or vardenafil or within 48 h of tadalafil) of a phosphodiesterase-5 inhibitor for erectile dysfunction (or pulmonary hypertension)... 

Nitroglycerin should not be used within 24 hours of taking sildenafil or vardenafil or within 48 hours of taking tadalafil because of the potential for life-threatening hypotension. 

Sildenafil or vardenafil within 24 hours or tadalafil within... 

Tadalafil Cialis 5-20 mg prior to intercourse Once daily... 

Sildenafil (Viagra ), tadalafil (Cialis ), and vardenafil (Levitra ) act by selectively inhibiting phosphodiesterase (PDE) type 5, an enzyme that breaks down cGMP. By inhibiting the breakdown of cGMP, smooth muscle relaxation is... 

The most dramatic difference between the three agents is tadalahl s extended duration of action, earning it the nickname the weekender drug. While sildenafil and vardenafil have average half-lives of 3 to 4 hours, tadalafil s half life is approximately 18 hours.18 The extended half-life allows for more spontaneous sexual activity over a couple of days, but may increase the duration of adverse effects and liklihood of drug interactions or sildenafil. 

Sildenafil (Viagra ) Tadalafil (Cialis ) Vardenafil (Levitra )... 

Selective ala-blockers (such as 0.4 mg tamsulosin every day) are appropriate in combination with tadalafil. 

Gresser U, Gleiter CH. Erectile dysfunction comparison of efficacy and side effects of the PDE-5 inhibitors sildenafil, vardenafil and tadalafil review of the literature. Eur J Med Res 2002 7 435-446. 

Erectile dysfunction is common, and initial treatment should include one of the oral medications currently available (e.g., sildenafil, vardenafil,tadalafil). 

Unless otherwise stated, general information applies to the entire class of phosphodiesterase inhibitors. Sildenafil is highlighted because it was the first to be marketed and is the most thoroughly studied. The newer agents tadalafil and vardenafil have different pharmacokinetic profiles (Table 83-3), drug-food interactions, and adverse effects. 

For maximal absorption, patients should avoid taking sildenafil or vardenafil with a fatty meal. A fatty meal does not affect absorption of tadalafil. / If the first dose is not effective, patients should continue trying for five to eight doses. Some patients benefit from titration up to 100 mg of sildenafil, 20 mg of vardenafil, or 20 mg of tadalafil. 

Sildenafil doses should be decreased when any potent cytochrome P450 3A4 inhibitor is used (e g., cimetidine, erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir, and saquinavir). Vardenafil doses vary accordingto which agent is used (2.5 mg q 72 h for ritonavir, 2.5 mg q 24 h for indinavir, ketoconazole 400 mg daily, and itraconazole 400 mg daily and 5 mg q 24 h for ketoconazole 200 mg daily, itraconazole200 mg daily, and erythromycin). Tadalafil doses are reduced only when it is used with the most potent cytochrome P450 3A4 inhibitors (e g., ketoconazole or ritonavir). 

Sildenafil and vardenafil decrease systolic/diastolic blood pressure by 8 to 10/5 to 6 mm Hg for 1 to 4 hours after a dose. Although most patients are asymptomatic, multiple antihypertensives, nitrates, and baseline hypotension increase the risk of developing adverse effects. Although tadalafil does not decrease blood pressure, it should be used with caution in patients with cardiovascular disease because of the inherent risk associated with sexual activity. 

Tadalafil inhibits type 11 phosphodiesterase, which is thought to account for the dose-related back and muscle pain seen in 7% to 30% of patients. 

S. Trefi, C. Routaboul, S. Hamieh, V. Gilard, M. Malet-Martino and R. Martino, Analysis of illegally manufactured formulations of tadalafil (Cialis ) by H NMR, 2D DOSY H NMR and Raman spectroscopy, J. Pharm. Biomed. Anal, 47, 103-113 (2008). 

Drugs that may interact with nitrates include alcohol, alteplase, aspirin, beta-blockers, calcium channel blockers, dihydroergotamine, heparin, nondepolarizing muscle relaxants, phenothiazines, phosphodiesterase inhibitors (eg, sildenafil, tadalafil, vardenafil), and vasodilators. 

TADALAFIL 10 mg taken prior to anticipated sexual activity. The dose may be increased to 20 mg or decreased to 5 mg, based on individual efficacy and tolerability. The maximum recommended dosing frequency is once daily in most patients. Tadalafil may be taken without regard to food. 

Tadalafil was shown to improve erectile function compared with placebo up to 36 hours following dosing. Therefore, take this into consideration when advising patients on optimal use of tadalafil. 

Hepatic function impairment- In mild or moderate hepatic impairment (Child-Pugh class A or B), do not exceed 10 mg once daily. In severe hepatic impairment (Child-Pugh class C), the use of tadalafil is not recommended. 

Concomitant medications - For patients taking concomitant potent inhibitors of CYP3A4 (eg, ketoconazole, ritonavir), the maximum recommended dose of tadalafil is 10 mg, not to exceed once every 72 hours. 

Pharmacology Sildenafil, tadalafil, and vardenafil are selective inhibitors of... 

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