Pronunciation: pap-PAV-uhr-een HIGH-droe-KLOR-ide
Class: Peripheral vasodilator
- Capsules, timed-release 150 mg
Directly relaxes tone of all smooth muscle, especially when spasmodically contracted. Causes vasodilatation of blood vessels of the coronary, cerebral, pulmonary and peripheral arteries; relaxes musculature of bronchi, GI tract, ureters and biliary system.
Readily absorbed from GI tract. Oral bioavailability is approximately 54%. T max is 1 to 2 h after a dose.
Drug localizes in fat depots and in the liver; remainder is distributed throughout the body. Protein binding is 90%.
Urine (inactive form). T 1/ 2 is 0.5 to 2 h. T 1/ 2 varies widely; constant levels can be maintained by giving drug at 6-h intervals.
Indications and UsageOral form
Relief of cerebral and peripheral ischemia associated with arterial spasm and myocardial ischemia complicated by arrhythmias.Parenteral form
Vascular spasm associated with acute MI (coronary occlusion), angina pectoris, peripheral and pulmonary embolism, peripheral vascular disease in which there is a vasospastic element, certain cerebral angiospastic states, visceral spasm (eg, ureteral, biliary, and GI colic).
Intracavernous injection for impotence.
Complete atrioventricular (AV) heart block; intracorporeal injection for impotence.
Dosage and AdministrationIschemia
PO 100 to 300 mg 3 to 5 times daily (immediate-release tablets) or 150 mg every 8 to 12 h or 300 mg every 12 h (sustained-release capsules).Vascular Occlusion
IV / IM Initial dose is 30 mg. Repeat doses are 30 to 120 mg every 3 h as needed.Impotence
IV 2.5 to 60 mg as intracavernous injection (usually combined with phentolamine mesylate).
Do not crush or allow patient to chew sustained-release capsules.
Store at room temperature.
Drug InteractionsCNS depressants
Effects may be additive.Levodopa
May reduce effectiveness of levodopa.
Lactated Ringer's solution incompatible with parenteral formulation; do not mix.
Laboratory Test Interactions
None well documented.
Increase in heart rate; slight increase in BP.
Depression; dizziness; vertigo; headache; drowsiness; sedation; lassitude; malaise; lethargy.
Flushing of face; sweating; pruritus.
Constipation; nausea; diarrhea; abdominal distress; dry mouth; anorexia.
Increased depth of respiration.
Category C .
Safety and efficacy not established.
Use drug with caution.
Hepatic hypersensitivity reported.
Drowsiness, weakness, diplopia, lassitude, depression, nystagmus, incoordination, coma, cyanosis, respiratory depression, anxiety, ataxia, headache, pruritic skin rashes, nausea, CNS depression, blurred vision, GI upset, vomiting, diaphoresis, sinus tachycardia, metabolic acidosis, hyperventilation, hyperglycemia, hypokalemia.
- Instruct patient to take medication at evenly spaced intervals throughout day.
- Advise patient with glaucoma to undergo regular eye examinations.
- Instruct patient to report the following symptoms to health care provider: flushing, sweating, headache, tiredness, jaundice, skin rash, nausea, anorexia, abdominal distress, constipation, or diarrhea.
- Advise patient to avoid smoking and intake of alcoholic beverages or other CNS depressants.
- Caution patient to avoid sudden position changes to prevent orthostatic hypotension.
- Advise patient that drug may cause dizziness, vertigo, and drowsiness, and to use caution while driving or performing other tasks requiring mental alertness.
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