| Yohimbine The
Libido Enhancing Tree Bark Extract
By Robert Mason,
Ph.D.
Yohimbine has been used for decades to help
with erectile dysfunction and enhance libido, in-fact it is the only FDA approved
aphrodisiac! (8)
Essentially, yohimbine is an extract from the bark of an
African tree known as cortnanthe yohimbe, or sometimes referred to as pausinystalia
yohimbe. One can find the bark extract yohimbe in most health food stores in many
countries, but the pharmaceutical pure extract yohimbine (as denoted by the difference
in the ending of the name), is actually an indole alkaloid that makes up less
than 1% of the volume of yohimbe bark, (Betz et al, 1995, Budavari 1996, Leo and
Foster, 1996).
Erectile Dysfunction:
As stated at the very beginning of the article,
long before Viagra® was available, yohimbine was the drug of choice to help
treat erectile dysfunction (ED). Why was this?
Well, specifically, yohimbine's
primary path of action is to act upon alpha-2 adrenergic nerve cells. These receptors
are also found in the abdominal and pelvic area. So yohimbine effectively helps
to block this part of the adrenergic system and as such, increases the amount
of adrenergic activity by increasing the availability of the neurotransmitters,
noradrenaline and acetylcholine (US PDR, 1994, Adaikan 1988). It is believed that
this blockade increases the flow of blood through the penis, whilst at the same
time decreasing the flow of blood out from the penis. The overall effect results
in improved erection frequency, strength and stamina.
The flaccid penis has
adrenaline almost permanently locked onto alpha-2 adrenergic receptors. Therefore,
in order to achieve an erection, the nerve impulses have to initiate a process
by which adrenaline is removed from these receptor sites. Yohimbine helps to prevent
adrenaline from docking to these receptors in the first place.
Unfortunately,
yohimbine tends to work best with a cumulative effect when it comes to ED, this
means that the dosages (to be most effective), usually have to be taken over a
period of 14-days, and in some men have been known to take as long as up to 6-weeks.
Thus, when Viagra® came to the market, it rapidly overtook yohimbine as the
drug of choice for ED, as clearly its affects are known to be far faster acting.
(Ed.- of course a billion Dollars worth of advertising also helped!)
However,
this article about yohimbine's actions are more focused on its abilities to improve
libido, (or sexual arousal), and we can state that Viagra® has little effect
in this regard.
Libido Enhancement:
The most likely explanation
of the reported affects of yohimbine's sexual arousal effects, which include increased
ejaculate, more intense orgasms and enhanced desire for intercourse, probably
lie in yohimbine's ability to increase noradrenaline levels by as much as 66%
(Grossman, 1993).
Noradrenaline has been described as the body's sex hormone
and it appears to stimulate the brain's sex center in the hypothalamus. As yohimbine
blocks the uptake of noradrenaline, it forces more of it into "general circulation,"
thus the heart rate increases, alertness is enhanced, more mental agitation occurs
and there is also a general proneness to improved arousal, whether it be sexual
or otherwise.
In an animal experiment, (4) that involved the intake of both
yohimbine and the recent ED drug apomorphine, (Ed.- there is more about apomorphine
in this bulletin in the other articles), it was noted that the two substances
were synergistic. Specifically, when combined they helped to reduce sexual exhaustion,
and there was a tendency to immediately resume copulation even after ejaculation.
The results of this study suggested that; "the dopaminergic system might
be the final pathway for the yohimbine-induced sexual behaviour expression."
This is of interest, because the other known dopamine enhancing substances such
as; deprenyl, bromocriptine and L-dopa have long been documented as enhancing
sexual drive, particularly for men, and thus it is believed that there is a strong
relationship between dopamine and libido. Therefore, to suggest that yohimbine
also acts upon dopamine and dopamine receptors as part of its ability to enhance
libido, just adds to its credibility as a scientifically proven aphrodisiac.
Side Effects and Contraindications:
As stated earlier, yohimbine is known
to increase heart rate and sometimes blood pressure, therefore persons suffering
with heart conditions should avoid yohimbine use. This caution should also be
extended to any individuals who are suffering from anxiety and panic attacks.
It is also known that yohimbine is contraindicated with MAO inhibitors, which
are often to be found in the action of many anti-depressants. Thus, a physician's
advice should be sought before starting on yohimbine, if you are taking any form
of anti-depression therapy.
Yohimbine remains a drug studied primarily for
men. There is very little data about the use of yohimbine in women, probably because
the primary medical use of yohimbine has been focused on erectile dysfunction
and male impotence. So, we must therefore suggest some caution for women, however
one British reference we came across, recommended that women interrupt their yohimbine
treatment for at least one week every two months, but it didn't elaborate any
further!
We may also want to extend caution to any individuals utilizing treatments
that can enhance dopamine and/ or adrenaline activity. This could include drugs
such as deprenyl, bromocriptine, hydergine, modafinil, adrafinil and L-dopa etc.
In such circumstances, caution is advised as the effects of any two combined are
likely to be synergistic, therefore there is a need to adjust both the dosages
downward.
Dosages:
Normal daily dosages for yohimbine for
the treatment of ED or impotence are 5mg two or three times daily. For general
sexual enhancement, a dose of 5mg or 10mg taken 30-minutes before sexual intercourse
can have a satisfactory to profound affect.
Other Factors:
Naturally,
there are a myriad of factors that can impede sexual performance and the "will"
to perform. To keep ourselves concerned to the more "physical" problems,
here are some other issues worth bearing in-mind, they include:
1. Caffeine
in coffee is a vasoconstrictor, (caffeine is also found in some soft drinks and
to a lesser extent tea and chocolate). Thus, caffeine acts to impede the penis'
ability to fill with blood.
2. The Brassica vegetables are known for their
rich content of indol-3-carbinol (I3C) and di-indolylmethane (DIM), both of which
have a powerful influence on estrogen metabolism; as-such they can help to readdress
the testosterone-estrogen balance which changes with age. (Ed- Jonathan Wright,
MD wrote about this in the Summer 2000 Anti-Aging Bulletin and Rick Cohen, MD
also addressed estrogens in men in the Fall 2001 Anti-Aging Bulletin).
3.
Nuts are high in several nutrients that have been credited with improving sexual
function, one of these is vitamin E which is a weak vasodilator, (meaning improved
blood flow). They also contain the amino acid arginine which can be used to produce
NO (nitric oxide). NO is the primary neurotransmitter used by the body to facilitate
erection. Furthermore, they contain zinc which is known to help production of
seminal fluids. (Note that shellfish, particularly oysters have long been touted
as sexual enhancers, probably because of their high content of zinc).
4.
Free testosterone enhancing substances can also have major libido benefit for
both men and women. (Ed.- some of these issues were discussed by Rick Cohen MD
in the Summer 2000 Anti-Aging Bulletin).
Conclusion:
Perhaps yohimbine's
greatest attribute is to be able to enhance sexuality in healthy subjects. Whilst
Yohimbine's use in the treatment of impotence has been limited, its general enhancing
affects, arousal stimulatory properties and improver of both the stamina and the
rigidity of the male organ has an overall tendency to improve sexual performance.
Accordingly, yohimbine can give a new potential and meaning to the lives of "older"
men.
The fact that yohimbine is a mainstay supplement of those in the X-rated
adult video business probably speaks for itself.
References:
1. Double-blind, placebo-controlled
safety and efficacy trial with yohimbine hydrochloride in the treatment of nonorganic
erectile dysfunction: Vogt HJ; Brandl P; Kockott G; Schmitz JR; Wiegand MH; Schadrack
J; Gierend M: Int J Impot. Res, 9(3):155-61 1997 Sep.
2. Therapeutic effects
of high dose yohimbine hydrochloride on organic erectile dysfunction. Teloken
C ; Rhoden EL ; Sogari P ; Dambros M ; Souto CA: J Urol, 159(1):122-4 1998 Jan.
3. Yohimbine, erectile capacity, and sexual response in men: Rowland DL ;
Kallan K ; Slob AK: Arch Sex Behav, 26(1):49-62 1997 Feb.
4. Yohimbine and
apomorphine increase sexual appetite. Yohimbine interacts with the dopaminergic
system to reverse sexual satiation: further evidence for a role of sexual motivation
in sexual exhaustion: Rodriguez-Manzo G: Eur J Pharmacol, 372(1):1-8 1999 May
7.
5. Effectiveness of yohimbine in the treatment of erectile disorder: four
meta-analytic integrations: Carey MP; Johnson BT: Arch Sex Behav, 25(4):341-60
1996 Aug.
6. Double-blind, placebo-controlled safety and efficacy trial with
yohimbine hydrochloride in the treatment of non-organic erectile dysfunction:
Vogt HJ; Brandl P; Kockott G; Schmitz JR; Wiegand MH; Schadrack J; Gierend M:
Int J Impot Res, 9(3):155-61 1997 Sep.
7. Dopamine and sexual behaviour:
Melis MR, Argiolas A: Neurosci. Biobehav. Rev. 1995 Spring, 19:1, 19-38.
8. US PDR 1998 No. 52, Medical Economics Company.
DISCLAIMER: ALL INFORMATION IS EDUCATIONAL AND PROVIDED UNDER IAS TERMS AND
CONDITIONS. IT DOES NOT, AND SHOULD NOT, REPLACE THE ADVICE OF YOUR PHYSICIAN.
Last Updated: Wednesday, August 21, 2002
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