Erectile dysfunction papaverine

Papaverine also has minimal narcotic properties. However, it does have vasodilator (blood vessel relaxant) properties, and because of this property it has been employed for both cognition enhancement and erectile dysfunction. 

Erectile dysfunction Injection of papaverine with or without phentolamine in the corpus cavernosum has been found to be effective in erectile dysfunction of penis. 

Papaverine Papaverine, molecular formula C20H21NO4, is an isoquinoline alkaloid isolated from poppy seeds Papaver somniferum, family Papaveraceae). This alkaloid is used mainly in the treatment of spasms and of erectile dysfunction. It is also used as a cerebral and coronary vasodilator. Papaverine may be used as a smooth muscle relaxant in microsurgery. In pharmaceutical preparations, papaverine is used in its salt form, e.g. hydrochloride, codecarboxylate, adenylate and teprosylate. The usual side-effects of papaverine treatment include polymorphic ventricular tachycardia, constipation, increased transaminase levels, hyperbihr-unemia and vertigo. 

A combination of phentolamine with the nonspecific smooth muscle relaxant papaverine, when injected directly into the penis, may cause erections in men with sexual dysfunction. Long-term administration may result in fibrotic reactions. Systemic absorption may lead to orthostatic hypotension priapism may require direct treatment with an -adrenoceptor agonist such as phenylephrine. Alternative therapies for erectile dysfunction include prostaglandins (see Chapter 18), sildenafil and other cGMP phosphodiesterase inhibitors (see Chapter 12), and apomorphine. 

Intracavernosal injection or urethral suppository therapy with alprostadil (PGE1) is a second-line treatment for erectile dysfunction. Doses of 2.5-25 meg are used. Penile pain is a frequent side effect, which may be related to the algesic effects of PGE derivatives however, only a few patients discontinue the use because of pain. Prolonged erection and priapism are side effects that occur in less than 4% of patients and are minimized by careful titration to the minimal effective dose. When given by injection, alprostadil may be used as monotherapy or in combination with either papaverine or phentolamine. 

In the treatment of male erectile dysfunction, direct injection of erectogenic dmgs such as papaverine into the corpus cavernosum is employed. Alternatively, a urethral pellet can be used. Figure 9.57 shows both modes of delivery. The advent of oral treatments with sildenafil will perhaps make this imperfect mode of administration redundant except for those patients in whom oral therapy fails. 

The vasoactive amines phentolamine and papaverine are occasionally used as intracavernosal therapy, usually in combination with alprostadil, although their use for erectile dysfunction is off-label. Moxisylyte is another vasoactive agent used as intracavernosal therapy. The drug is approved in several European countries, but is not approved in the United States. The advantages over alprostadil are that with moxisylyte, sexual stimulation is still required to achieve full erection and that detumescence occurs on ejaculation. 

In 1982, a new era for erectile dysfunction started when Virag (156) showed that penile injection of a vasoactive amine—papaverine (9)—could result in erection without sexual... 

Although many other agents, including papaverine and phen-tolamine, have been used off-label for intracavernosal therapy, al-prostadil is preferentially prescribed. This is because the FDA has approved intracavernosal alprostadil for erectile dysfunction, and because it has a low potential for causing prolonged erections and priapism. 

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. ... 

Other intracorporal agents used to induce penile erections include papaverine, a drug with a relaxant effect on smooth muscle, and phentolamine, an a-adrenergic receptor blocker. Yohimbine, an a2-adrenoreceptor antagonist, enhances noradrenergic neurotransmission and may improve erectile dysfunction via adrenergic system activation. 

Bechara A, Casabe A, Cheliz G, et al. Comparative study of papaverine plus phentolamine versus prostaglandin Ei in erectile dysfunction. J Urol 1997 157 2132-2134. 

There appear to be no published reports of adverse interactions between intracavemous alprostadil (prostaglandin E,) and other drugs used for erectile dysfunction, but some manufacturers say that smooth muscle re-laxants such as papaverine and other drugs used to induce erections such as alpha-blocking drugs [e.g. intracavernosal phentolamine] should not be used concurrently because of the risks of priapism (painful prolonged abnormal erection). ... 

Fitzgerald SW, Erickson SJ, Foley WD et al (1991) Color Doppler sonography in the evaluation of erectile dysfunction patterns of temporal response to papaverine. AJR Am J Roentgenol 157 331-336... 

---