Yocon ® Yohimbine Hydrochloride, U.S.P.
Yohimbine is a 3alpha -15alpha -20beta -17alpha -hydroxy Yohimbine-16alpha - carboxylic acid methyl ester. The alkaloid is found in Rubaceae and related trees. Also in Rauwolfia Serpentina (L) Benth. Yohimbine is an indolalkylamine alkaloid with chemical similarity to reserpine. It is a crystalline powder, odorless. Each compressed tablet contains (1/12 gr.) 5.4 mg of Yohimbine Hydrochloride.
Yocon is indicated as a sympathicolytic and mydriatic. It may have activity as an aphrodisiac.
Yocon blocks presynaptic alpha-2 adrenergic receptors. Its action on peripheral blood vessels resembles that of reserpine, though it is weaker and of shorter duration. Yohimbine's peripheral autonomic nervous system effect is to increase parasympathetic (cholinergic) and decrease sympathetic (adrenergic) activity. It is to be noted that in male sexual performance, erection is linked to cholinergic activity and to alpha-2 adrenergic blockade which may theoretically result in increased penile inflow, decreased penile outflow or both.
Yohimbine exerts a stimulating action on the mood and may increase anxiety. Such actions have not been adequately studied or related to dosage although they appear to require high doses of the drug. Yohimbine has a mild anti-diuretic action, probably via stimulation of hypothalamic centers and release of posterior pituitary hormone.
Reportedly, Yohimbine exerts no significant influence on cardiac stimulation and other effects mediated by beta-adrenergic receptors. Its effect on blood pressure, if any, would be to lower it; however, no adequate studies are at hand to quantitate this effect in terms of Yohimbine dosage.
DOSAGE AND ADMINISTRATION:
Experimental dosage reported in treatment of erectile impotence:1, 3, 4 1 tablet (5.4 mg) 3 times a day, to adult males taken orally. Occasional side effects reported with this dosage are nausea, dizziness or nervousness. In the event of side effects dosage is to be reduced to 1/2 tablet 3 times a day, followed by gradual increases to 1 tablet 3 times a day. Reported therapy not more than 10 weeks.3
Renal diseases, and patients sensitive to the drug. In view of the limited and inadequate information at hand, no precise tabulation can be offered of additional contraindications.
Generally, this drug is not proposed for use in females and certainly must not be used during pregnancy. Neither is this drug proposed for use in pediatric, geriatric or cardio-renal patients with gastric or duodenal ulcer history. Nor, should it be used in conjunction with mood-modifying drugs such as antidepressants, or in psychiatric patients in general.
Yohimbine readily penetrates the CNS and produces a complex pattern of responses in lower doses than required to produce peripheral alpha-adrenergic blockade. These include, anti-diuresis, a general picture of central excitation including elevation of blood pressure and heart rate, increased motor activity, irritability, and tremor. Sweating, nausea and vomiting are common after parenteral administration of the drug.1,2 Also dizziness, headache, skin flushing reported when used orally.1,3
Yocon ® (Yohimbine Hydrochloride, USP) Tablets 1/12 gr 5.4 mg
Bottles of 100 - NDC 0516-0001-01
Bottles of 1,000 - NDC 0516-0001-10
- A. Morales et al., New England Journal of Medicine: 1221. November 12, 1981.
- Goodman, Gilman - The Pharmacological basis of Therapeutics 6th ed., p. 176-188, McMillan
- Weekly Urological Clinical letter, 27:2, July 4, 1983
- A. Morales et al., The Journal of Urology 128: 45-47, 1982.