Sildenafil Nitrates

Isordil is a proprietary (trade name) preparation of isosorbide dinitrate, a nitrate. Sildenafil, the active ingredient of Viagra, interacts with nitrates and the two active ingredients should not be administered concurrently, as a significant hypotensive effect may occur. 

Uses Prevention/Rx of angina pectoris Action Relaxes vascular smooth muscle Dose 5-10 mg PO bid, w/ the 2 doses 7 h apart or XR (Imdur) 30-60 mg/d PO, max 240 mg Caution [C, ] Contra Head trauma/cerebral hemorrhage (can ICP), w/ sildenafil, tadalafil, vardenafil Disp Tabs 10, 20 mg XR 30, 60, 120 mg SE HA, dizziness, X- BP Interactions T Hypotension W/ ASA, CCB, nitrates, sildenafil, EtOH EMS Metabolite of isosorbide dinitrate 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... 

Vasodilators are a group of dtugs, which relax the smooth muscle cells of the blood vessels and lead to an increased local tissue blood flow, a reduced arterial pressure and a reduced central venous pressure. Vasodilators reduce the cardiac pre-load as well as after-load and thereby reduce cardiac work. They are used in a variety of conditions including hypertension, cardiac failure and treatment/prevention of angina pectoris. Major groups are Ca2+-channel blockers (e.g. dihydropyridines), NO-donators (e.g. organic nitrates), K+-channel openers (minoxidil), phosphodiesterase inhibitors (e.g. sildenafil), Rho-kinase inhibitors (e.g. Y27632) or substances with unknown mechanism of action (e.g. hydralazine). Inhibitors of the... 

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. 

Patients who are using certain drugs for erectile dysfunction (eg, sildenafil citrate), because these drugs have been shown to potentiate the hypotensive effects of organic nitrates (sublingual tablets, lingual spray, transdermal). 

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. 

Caution [C, ] CrCl <30 Contra Component sensitivity, asthma, severe COPD, sinus bradycardia Disp Soln SE Irritation, bitter taste, superficial keratitis, ocular allergic Rxn EMS Drug is absorbed systemically OD May cause electrolyte disturbances (K), acidosis and bradycardia monitor ECG Doxazosin (Cardura, Cardura XL) [Antihypertensive/Alpha Blocker] Uses HTN symptomatic BPH Action < [-Adrenergic blocker relaxes bladder neck smooth muscle Dose HTN Initial 1 mg/d PO may be T to 16 mg/d PO BPH Initial 1 mg/d PO, may T to 8 mg/d XR 2-8mg qAM Caution [B, ] Use w/ PDE5 inhibitor (eg, sildenafil) can cause 1 BP Contra Component sensitivity Disp Tabs SE Dizziness, HA, drowsiness, sexual dysfxn, doses >4 mg T postural BP risk Interactions T Effects W/ nitrates, antihypertensives, EtOH i effects W/ NSAEDs, butcher s broom -t effects OF clonidine EMS Concurrent EtOH use can T drowsiness syncope may occur w/in 90 min of initial dose OD May cause profound hypotension place pt in supine position, give IV fluids, use pressors if needed... 

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