Melatonin "half-life"?

Jo Robinson jor at teleport.com
Thu Nov 23 13:10:48 EST 1995


Robert Brown (bobbrown at tiac.net) wrote:
: Jo, or whoever else has info:  What is the pattern of blood concentrations
: of melatonin in humans from one-oral-dose-at-bedtime supplementation?
: Is each days supplement essentially washed out by the next day, or does it
: build up somewhat over a period of time?

Melatonin has a very short half-life, from 45-60 minutes.  How long melatonin
remains in your bloodstream depends on a number of factors, including
the size of the dose and the efficiency of your liver.  On average,
doses smaller than 10 mg. are gone from the bloodstream within 12 hours.
But people whose livers allow a high percentage of melatonin to enter
the general bloodstream intact can have sustained concentrations for
12 or more hours when given a much smaller dose.  Older people, in 
general, allow more melatonin to pass into the bloodstream.  One of the
great difficulties facing researchers who are now studying melatonin
in clinical trials is the great variability in blood levels from
a similar dose -- as much as 35-fold.  [Br. J. of Clinical Pharmacology
1985; 19:517-21.]

It has been well established that melatonin does not remain in circulation
for long, but whether or not it builds up in the tissues is another
question, one that has yet to be resolved.

Jo


Coauthor, with Russel J. Reiter, Ph.D., Melatonin: Your Body's Natural
WOnder Drug.  (Bantam 1995)
--
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|       Jo Robinson		    |            jor at teleport.com             |
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