Papaverine adverse effects

Levodopa interacts with many different drugs. When levodopa is used with phenytoin, reserpine, and papaverine, there is a decrease in response to levodopa The risk of a hypertensive crisis increases when levodopa is used with the monoamine oxidase inhibitors (see Chap. 31). Foods high in pyridoxine (vitamin B6) or vitamin B6 preparations reverse the effect of levodopa However, when carbidopa is used with levodopa, pyridoxine has no effect on the action of levodopa hi fact, when levodopa and carbidopa are given together, pyridoxine may be prescribed to decrease the adverse effects associated with levodopa... 

Dicyclomine hydrochloride has one eighth of the neii-rotropic activity of atropine and approximately twice the musculotropic activity of papaverine. This preparation. liN introduced in 1950. has minimized the adverse effects asso. dated with the atropine-type compounds. It is used for its spasmolytic effect on variou.s smtxrth muscle spa.snts. particularly those associated with the GI tract. It is also useful in dysmenorrhea. pylorospa.sm. and biliary dysfunction. 

Papaverine is not FDA approved for erectile dysfunction. Intracavernosal papaverine alone is not commonly used for management of erectile dysfunction because large doses are required, and these produce dose-related adverse effects priapism, corporal fibrosis, hypotension, and hepatotoxicity. Papaverine is more often administered in lower doses combined with phentolamine and/or alprostadil. A variety of formulae have been used, but no one mixture has been proven better than other mixtures (see Table 81-6). Combination formulations are considered to be safer and associated with the potential for fewer serious adverse effects than high doses of any one of these agents. ... 

A portion of each papaverine dose is systemicaUy absorbed, and its prolonged plasma half-life of 1 hour contributes to adverse effects. The usual dose of papaverine is 7.5 to 60 mg when used as a siugle agent for intracavernosal injection. When used in combination, the dose decreases to 0.5 to 20 mg (see Table 81-6). 

Phentolamine has most often been administered as an intracavernosal injection. Monotherapy is avoided, as large doses are required for an erection, and at these doses systemic hypotensive adverse effects would be prevalent. Most often, phentolamine has been used in combination with other vasoactive agents for intracavernosal administration. A ratio of 30 mg papaverine to 0.5 to 1 mg phentolamine is typical, and the usual dose ranges from 0.1 mL to 1 mL of the mixture. Such a mixture promotes local effects of phentolamine and minimizes systemic hypotensive adverse effects (see Table 81-6). ... 

Observational studies Tincture of opium is a preparation of powdered opium, which contains morphine, codeine, papaverine, and alcohol. It is used as an antidiarrheal agent, to treat neonatal abstinence syndrome, in the management of pain, and traditionally for the management of opioid dependency in some Asian countries. In an open study, opium-dependent subjects were allocated to three different doses of tincture of opium twice a day 10 ml (6.66 mg morphine equivalents n = 13), 20 ml (13.3 mg morphine equivalents n = 8), and 30 ml (20 mg morphine equivalents n = 11) [1 j. In all the subjects tincture of opium effectively suppressed withdrawal symptoms without causing significant adverse effects. 

Chadwick GM, Asher AL, Van Der Veer CA, Pollard RJ. Adverse effects of topical papaverine on auditory nerve function. Acta Neurochirurg 2008 150(9) 901-9. 

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