Medical Evidence
Pharmacokinetics of Glucosamine in Man
I.Setnikar-a. R. Palumbob. S. Canalic, and G. Zanoloc
Rotta Research Laboratorium Sp.A.a, Monza, Policlinico di Perugiab
, Perugia. and RBM -Instituto di Ricerche Biomediche A. Marxer,c
Ivrea Italy
Summary: The pharmacokinetics
of glucosamine sulfate (CAS 29031-19-4 was investigated in 6 healthy
male volunteers per administration route) using, 14C uniformly
labelled glucosamine sulfate and administering it in single dose
by intravenous (i.v.) intramuscular (i.m.) or oral route.
The results show that after i.v. administration the radioactivity
due to glucosamine appears in plasma and is rapidly eliminated
with an initial t1/2 of 0.28 h. 1-2 h after administration the
radioactivity due to glucosamine disappears almost completely
and is replaced by a radioactivity originating from plasma proteins,
in which glucosamine or its metabolites are incorporated. This
radioactivity reaches a peak after 8-10 h and then declines with
a t1/2 of 70 h. About 28 % of the administered radioactivity is
recovered in the urine of the 120 h following the administration
and less than 1% is recovered in the feces. After i.m. administration
on similar pharmacokinetic patterns are observed. After oral administration
a proportion close to 90 % of glucosamine sulfate is absorbed.
Free glucosamine is not detectable in plasma. The radioactivity
incorporated in the plasma proteins follows pharmacokinetic patterns
which are similar to those after i.v. or i.m. administration,
but its concentration in plasma is about 5 times smaller than
that after parenteral administration. The AUC after oral administration
is 26 % of that after i.v. or i.m. administration.
The smaller plasma levels of radioactivity after oral administration
are probably due t o a first pass effect in the liver which metabolizes
a notable proportion of glucosamine into smaller molecules and
ultimately to CO2, water and urea.
Results: The results confirm
previous investigations in rats and dogs showing that also in
man glucosamine sulfate is a prodrug for glucosamine that is well
absorbed after oral administration and that, after i.v., i.m.
or oral administration, diffuses into several tissues, including
bones and articular cartilages.
Source: Arzneimittel-Forschung/Drug
Research 43 (II), 10, 1109-1113 (1993)
Dr. Theo's Comments: Another
study to show that oral glucosamine is absorbed in humans and
diffuses into joint cartilage.
