产品特点
1
TAGAMET® PRODUCT INFORMATION
(CIMETIDINE)
DESCRIPTION
TAGAMET (cimetidine) is a histamine
H2-receptor antagonist. Chemically it is: 2-cyano-1-methyl-
3-{2-(5-methylimidazol-4-yl-methylthio)ethyl} guanidine.
HN
N
H
3
C
S
N
H
N
H
N
CN
CH
3
Cimetidine is an odourless white to off-white powder, slightly soluble
in water.
PHARMACOLOGY
TAGAMET is a histamine H2-receptor antagonist and represents a new
class of pharmacological
agents. It was the first available agent that blocked the action
of histamine at the histamine H2-
receptor site of the parietal cells and does so by competitive
inhibition.
Pharmacologically, TAGAMET does not exhibit classical anticholinergic
effects. Studies have
shown that TAGAMET inhibits both daytime and nocturnal basal
gastric acid secretion. TAGAMET
also inhibits gastric acid secretion stimulated by food, histamine,
pentagastrin, caffeine and insulin.
TAGAMET has been shown by _in vitro_ studies to be
a specific competitive H2-receptor antagonist
without significant interaction at catecholamine,
β-receptors, histamine H1-receptors or muscarinic
receptors.
Its potency in terms of administered dose and, more meaningfully, in
terms of blood concentrations
achieved, is very similar in man and in experimental animals.
Thus, in all species studied a blood
concentration of about 2
μmol/L is associated with 50% inhibition of maximal acid output.
In chronic toxicity studies in dogs, some animals administered
504mg/kg showed evidence of liver
and kidney damage.
The kinetics of TAGAMET and its absorption, metabolism and
excretion are essentially similar in
man, rat and dog.
2
HUMAN PHARMACOLOGY:
Pharmacokinetic studies carried out in humans have demonstrated
that cimetidine is well absorbed
orally. Oral absorption studies carried out using a 200mg dose have
resulted in blood levels
averaging 2.8
μmol/L (0.7mg/L) occurring at times ranging from 45 - 75
minu
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