Overview
DESCRIPTION Papaverine Hydrochloride, USP, is the hydrochloride of an alkaloid obtained from opium or prepared synthetically. It belongs to the benzylisoquinoline group of alkaloids. It does not contain a phenanthrene group as do morphine and codeine. Papaverine Hydrochloride, USP, is 6,7-dimethoxy-1- veratrylisoquinoline hydrochloride and contains, on the dried basis, not less than 98.
Mechanism of Action
CLINICAL PHARMACOLOGY The most characteristic effect of papaverine is relaxation of the tonus of all smooth muscle, especially when it has been spasmodically contracted. Papaverine Hydrochloride apparently acts directly on the muscle itself. This relaxation is noted in the vascular system and bronchial musculature and in the gastrointestinal, biliary and urinary tracts . The main actions of papaverine are exerted on cardiac and smooth muscle. Papaverine relaxes various smooth muscles, especially those of larger arteries; this relaxation may be prominent if spasm exists. The antispasmodic effect is a direct one and unrelated to muscle innervation, and the muscle still responds to drugs and other stimuli causing contraction.
Indications
- INDICATIONS AND USAGE Papaverine is recommended in various conditions accompanied by spasm of smooth muscle, such as vascular spasm associated with acute myocardial infarction (coronary occlusion), angina pectoris, peripheral and pulmonary embolism, peripheral vascular disease in which there is a vasospastic element, or certain cerebral angiospastic states; and visceral spasm, as in ureteral, biliary, or gastrointestinal colic.
Common Doses
- 4 mL
Dosage
DOSAGE AND ADMINISTRATION Papaverine Hydrochloride may be administered intravenously or intramuscularly. The intravenous route is recommended when an immediate effect is desired, but the drug must be injected slowly over the course of 1 or 2 minutes to avoid uncomfortable or alarming side effects. Parenteral administration of papaverine hydrochloride in doses of 1 to 4 mL is repeated every 3 hours as indicated. In the treatment of cardiac extrasystoles, 2 doses may be given 10 minutes apart.
Contraindications
- CONTRAINDICATIONS Intravenous injection of papaverine is contraindicated in the presence of complete atrioventricular heart block. When conduction is depressed, the drug may produce transient ectopic rhythms of ventricular origin, either premature beats or paroxysmal tachycardia. Papaverine Hydrochloride is not indicated for the treatment of impotence by intracorporeal injection. The intracorporeal injection of papaverine hydrochloride has been reported to have resulted in persistent priapism requiring medical and surgical intervention.
Side Effects
- ADVERSE REACTIONS The following side effects have been reported: general discomfort, nausea, abdominal discomfort, anorexia, constipation or diarrhea, skin rash, malaise, vertigo, headache, intensive flushing of the face, perspiration, increase in the depth of respiration, increase in heart rate, a slight rise in blood pressure, and excessive sedation. Hepatitis, probably related to an immune mechanism, has been reported infrequently. Rarely, this has progressed to cirrhosis.
Interactions
- No major interactions listed on the FDA label. Always consult a healthcare professional.