Tadalafil drug interactions

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. 

Flypersensitivity to any component of the tablet administration with nitrates (either regularly and/or intermittently) and nitric oxide donors because of the potentiation of hypotension (see Drug Interactions) coadministration with alpha-blockers (vardenafil only) coadministration with alpha-blockers other than 0.4 mg/day tamsulosin (tadalafil only). 

Sildenafil, tadalafil and vardenafil have similar, although not identical, mechanisms of action and structural similarity, and are metabolized primarily by the CYP3A4 isoenzymes, Vardenafil is 32-fold more potent than sildenafil in inhibiting phosphodiesterase type 5. Tadalafil has a quicker onset of action and a longer duration of action - around 36 hours - hence the need to be aware of the potential for adverse drug interactions for nearly 2 days after the intake of a single tablet. 

Drug-drug iuteractions Tadalafil The interaction of ambrisentan with tadalafil has been investigated in a crossover study in 26 healthy adults [78 ]. In contrast to bosentan, there was no interaction, and dosage adjustment is not necessary during combination therapy. 

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. 

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. 

Isosorbide Dinitrate Hydralazine (BiDil) [Antianginal, Antihypertensive/Vasodilator, Nitrate] Uses HF in African Amer-icans improve survival functional status, prolong time between hospitalizations Action Relaxes vascular smooth muscle peripheral vasodilator Dose Initially 1 tab tid PO (if not tol ated reduce to 1/2 tab tid), titrate >3-5 d as tolerated Max 2 tabs tid Caution [C, /-] recent MI, syncope, hypovolemia, hypotension, hep impair Contra For children, concomitant use w/ PDE5 inhibitors (sildenafil) Disp Tabs SE HA, dizziness, orthostatic hypotension, sinusitis, GI distress, tach, paresthesia, amblyopia Interactions t Risk of severe hypotension W/ antihypertensives, ASA, CCBs, MAOIs, phenothiazides, sildenafil, tadalafil, vardenafil, EtOH X pressor response Wf i -1- effects W7 NSAIDs EMS Use ASA, antihypertensives and CCBs w/ caution, may t hypotension concurrent Viagra-type drug use can lead to profound hypotension concurrent EtOH use can t effects OD May cause N/V, profound hypotension, skin flushing, HA from ICP, bradycardia, confusion, and circulatory collapse activated charcoal may be effective, epi use is contraindicated... 

No clinically relevant interactions appear to occur between sildenafil, tadalafil or vardenafil and most antihypertensive drugs. The exceptions may be diltiazem and verapamil. The potentially serious interactions of sildenafil, tadalafil and vardenafil with the alpha blockers and nitrates are discussed elsewhere. See Phosphodiesterase type-5 inhibitors + Alpha blockers , p.l268 and Phosphodiesterase type-5 inhibitors -I- Nitrates , p.l272. 

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