Papaverine

Papaverine is an opium alkaloid used primarily in the treatment of visceral spasm, vasospasm (especially those involving the heart and the brain), and occasionally in the treatment of erectile dysfunction. While it is found in the opium poppy, papaverine differs in both structure and pharmacological action from the other opium alkaloids (opiates).

Uses
Papaverine is approved to treat spasms of the gastointestinal tract, bile ducts and ureter and for use as a cerebral and coronary vasodilator in subarachnoid hemorrhage (combined with balloon angioplasty) and coronary artery bypass surgery. Papaverine may also be used as a smooth muscle relaxant in microsurgery where it is applied directly to blood vessels.

The in vivo mechanism of action is not entirely clear, but an inhibition of the enzyme phosphodiesterase causing elevation of cyclic AMP levels is significant. It may also alter mitochondrial respiration.

It is also commonly used in cryopreservation of blood vessels along with other glycosaminoglycans and protein suspensions. Functions as a vasodilator during cryopreservation when used in conjunction with verapamil, phentolamine, nifedipine, tolazolines, or nitroprusside.

Papaverine is also being investigated as a topical growth factor in tissue expansion with some success.

Side effects
Frequent side effects of papaverine treatment include polymorphic ventricular tachycardia, constipation, interference with sulphobromophthalein retention test (used to determine hepatic function), increased transaminase levels, increased alkaline phosphatase levels, somnolence, and vertigo.

Rare side effects include flushing of the face, hyperhidrosis (excessive sweating), cutaneous eruption, arterial hypotension, tachycardia, lack of appetite, jaundice, eosinophilia, thrombopenia, mixed hepatitis, headache, allergic reaction, chronic active hepatitis, and paradoxical aggravation of cerebral vasospasm.

Formulations and trade names
Papaverine is available as a conjugate of hydrochloride, codecarboxylate, adenylate, and teprosylate. It was also once available as a salt of hydrobromide, camsylate, cromesilate, nicotinate, and phenylglycolate. The hydrochloride salt is available for intramuscular, intravenous, rectal and oral administration. The teprosylate is available in intravenous, intramuscular, and orally administered formulations. The codecarboxylate is available in oral form, only, as is the adenylate.

The codecarboxylate is sold under the name Albatran®, the adenylate as Dicertan®, and the hydrochloride salt is sold variously as Artegodan® (Germany), Cardioverina® (countries outside Europe and the United States), Dispamil® (countries outside Europe and the United States), Opdensit® (Germany), Panergon® (Germany), Paverina Houde® (Italy, Belgium), Pavacap (United States), Pavadyl® (United States), Papaverin-Hamelin® (Germany), Paveron® (Germany), Spasmo-Nit® (Germany), Cardiospan®, Papaversan®, Cepaverin®, Cerespan®, Drapavel®, Forpaven®, Papalease®, Pavatest®, Paverolan®, Therapav® (France), Vasospan®, Cerebid®, Delapav®, Dilaves®, Durapav®, Dynovas®, Optenyl®, Pameion®, Papacon®, Pavabid®, Pavacen®, Pavakey®, Pavased®, Pavnell®, Alapav®, Myobid®, Vasal®, Pamelon®, Pavadel®, Pavagen®, Ro-Papav®, Vaso-Pav®, Papanerin-hcl®, Qua bid®, Papital T.R.®, Paptial T.R.®, Pap-Kaps-150®.