General information

Papaverine is an alkaloid present in opium, but it is not related chemically or pharmacologically to other opium alkaloids. It has a direct relaxant effect on smooth muscle, partly attributable to inhibition of phosphodiesterase.

Systemic adverse reactions reported are hypotension and dizziness and, in rare cases, abnormal liver function tests [ ].

Organs and systems

Cardiovascular

Severe hypotension has been reported after intracisternal instillation of papaverine during clipping of an intracranial aneurysm [ ]. In one case hypotension after intracisternal instillation of papaverine was accompanied by bradycardia and sinus arrest [ ] and in another it was followed by cardiac arrest and death [ ]. However, in another case acute hypertension and tachycardia occurred [ ].

Nervous system

Papaverine is effective in the control of acute renal colic pain and is a good alternative when non-steroidal anti-inflammatory drugs are contraindicated. Only minor adverse reactions, mainly dizziness and sleepiness, were reported in a randomized comparison of papaverine and sodium diclofenac in 86 patients with acute renal colic. These adverse reactions were experienced by 4 of 29 patients who were given papaverine [ ].

Transient facial nerve palsy has been reported soon after topical of papaverine during surgery for a vestibular schwannoma [ ]. There were no changes in auditory brainstem responses. A postoperative facial palsy improved after several hours and was normal at follow-up 1 month later. In another case a 61-year-old woman had papaverine instilled intracisternally and developed transient mydriasis, which resolved within 90 minutes, and a facial nerve palsy, which took 2 months to recover [ ].

Rarely, papaverine can cause generalized convulsions after topical application during aneurysm surgery [ ].

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