Yohimbine

Other Names Aphrodin, corymbin, corynin, hydroergotocin, johimbin, quebrachin, quebrachina, yohimbenin, N yohimbin, yohimbina, yohimbinum, yohimvetol Substance type: aspidosperma alkaloid, indole alkaloid Yohimbine was first extracted from the bark of Pausinystalia yohimba and described in the nineteenth century. It is a typical alkaloid in plants from the Apocynaceae Family and is related to the Rauvolfia alkaloids, and it constitutes the primary alkaloid (1 0/0) in Alstonia angustifolia. It is also present in some species of Rauvolfia, especially the African species Rauvolfia macrophylla Stapf (Timmins and Court 1974). Yohimbine was once regarded as an MAO inhibitor, a view that is no longer considered accurate. Rather, it is simply an a -adrenergic blocker that consequently stimulates the release of noradrenaline at the nerve endings. This makes noradrenaline available in the corpus cavernosum and results in an erection (Roth et al. 1994, 955*; Wren 1988,292*). As a sympathicolytic agent, [yohimbine] dilates the peripheral blood vessels and reduces blood pressure. The aphrodisiac effect is explained through a vasodilatation of the genital organs and an increased excitability of the reflexes in the sacral medulla. (Roth et al. 1994,545*) Yohimbine's aphrodisiac and virility-enhancing effects, and its therapeutic efficaciousness in treating impotence, have been demonstrated in a number of clinical double-blind studies (Buffum 1982; Miller 1968; Sobotka 1969).505 Consequently, yohimbine hydrochloride has been approved as a specific medicine for the treatment of impotence (sexual neurasthenia). The recommended dosage is 5 to 10 mg taken three times daily as a short-term treatment over three to four weeks. Higher individual dosages (15 to 25 mg) result in psychoactive effects that are somewhat reminiscent of those of LSD, but with much less emotional content and an emphasis on physical phenomena (sexual desire, erotic enjoyment, and increased sensations of pleasure). Overdoses can be unpleasant but do not appear to be particularly dangerous (cf. Lewin 1992, 750*): A chemist had taken an almost 1000-fold dosage (1.8 g). He became unconscious for a few hours (during which time a pronounced priapism was observed) but was able to be discharged from the hospital within a day. (Roth et al. 1994,956*) Commercial Forms and Regulations The alkaloid is available as yohimbine hydrochloride. Yohimbine is a prescription medication.

Plants ContainingYohimbine (from Geschwinde 1996, ·145 f. *; Hofmann 1954;Lewin 1992*; Rompp 1995,5093*; Roth et al. 1994*; supplemented) Stock Plant Distribution Alstonia spp.   Alstonia angustifolia Old World Alstonia scholaris Southeast Asia Aspidosperma South America quebracho-blanco   Catharanthus lanceus North America Corynanthe spp. Africa Mitragyna stipulosa Africa (cf.palm wine)   Pausinystalia yohimba West Africa Pausirtystalia· macroceras   Pausinystaliatrillesii   Rauvolfia spp.   Rauvolfia macrophylla Africa Stapf   Rauvolfia serpentina   Benth.   Rauvolfia volkensii Africa Vincaspp. Africa (cf. Catharanthus roseus)   Literature See also the entries for Alstonia scholaris, Corynanthe spp., and Pausinystalia yohimba. Buffum, John. 1982. Pharmacosexology: The effects of drugs on sexual function-a review. Journal of Psychoactive Drugs 14 (1-2): 5-44. Finch, N., and W. I. Taylor. 1962. Oxidative transformation of indole alkaloids. 1: Preparation of oxindoles from yohimbine. Journal of the American Chemical Society 84:3871-77. Hofmann, Albert. 1954. Die Isolierung weiterer Alkaloide aus Rauwolfia serpentina Benth. Helvetica Chimica Acta 37:849-65. Lambert, G. A., W. J. Lang, E. Friedman, E. Meller, and S. Gershon. 1978. Pharmacological and biological properties of isomeric yohimbine alkaloids. European Journal ofPharmacology 49:39-48. Leary, Timothy. 1985. Auf der Suche nach dem wahren Aphrodisiakum und e1ektronischer Sex. Sphinx Magazin 35. Miller, W. W. 1968. Afrodex in the treatment of male impotence: A double-blind cross-over study. Current Therapeutic Research 10:354-59. Poisson, J. 1964. Recherches recentes sur les alcaloYdes du pseudocinchona et du yohimbine. Ann. Chim. 9:99-121. Porst, H. 1996. Orale und intracavernose Pharmakotherapie. TW Urologie Nephrologie 8 (2): 88-94. Sobotka, J. J. 1969. An evaluation of Afrodex in the management of male impotency: A double-blind cross-over study. Current Therapeutic Research 11:87-94. Timmins, Peter, and William E. Court. 1974. Alkaloids of Rauwolfia macrophylla. Phytochemistry 13:281-82. Weyers, Wolfgang. 1982. Die Empfehlung in der Selbstmedikation. Heusenstamm: Keppler Verlag.