METHYLDOPA tablet

国家: 美国

语言: 英文

来源: NLM (National Library of Medicine)

有效成分:

METHYLDOPA (UNII: 56LH93261Y) (METHYLDOPA ANHYDROUS - UNII:M4R0H12F6M)

可用日期:

Cardinal Health

INN（国际名称）:

METHYLDOPA

组成:

METHYLDOPA ANHYDROUS 250 mg

处方类型:

PRESCRIPTION DRUG

授权状态:

Abbreviated New Drug Application

产品特点

METHYLDOPA- METHYLDOPA TABLET
CARDINAL HEALTH
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DESCRIPTION
Methyldopa is an antihypertensive and is the L-isomer of
alpha-methyldopa. It is levo-3-(3,4-
dihydroxyphenyl)-2-methylalanine sesquihydrate. Methyldopa is supplied
as tablets for oral
administration, containing 250 mg and 500 mg of methyldopa. The amount
of methyldopa is calculated
on the anhydrous basis. Its molecular formula is C
H NO •1 1/2 H O, with a molecular weight of
238.24, and its structural formula is:
Methyldopa is a white to yellowish white, odorless fine powder and is
sparingly soluble in water.
The tablets contain the following inactive ingredients: colloidal
silicon dioxide, croscarmellose
sodium, hypromellose, magnesium stearate, microcrystalline cellulose,
polydextrose, polyethylene
glycol, sodium lauryl sulfate, titanium dioxide, triacetin, FD&C
yellow #6 aluminum lake and FD&C
blue #2 aluminum lake.
CLINICAL PHARMACOLOGY
Methyldopa is an aromatic-aminoacid decarboxylase inhibitor in animals
and in man. Although the
mechanism of action has yet to be conclusively demonstrated, the
antihypertensive effect of methyldopa
probably is due to its metabolism to alpha-methylnorepinephrine, which
then lowers arterial pressure by
stimulation of central inhibitory alpha-adrenergic receptors, false
neurotransmission, and/or reduction
of plasma renin activity. Methyldopa has been shown to cause a net
reduction in the tissue concentration
of serotonin, dopamine, norepinephrine, and epinephrine.
Only methyldopa, the L-isomer of alpha-methyldopa, has the ability to
inhibit dopa decarboxylase and to
deplete animal tissues of norepinephrine. In man, the antihypertensive
activity appears to be due solely
to the L-isomer. About twice the dose of the racemate
(DL-alpha-methyldopa) is required for equal
antihypertensive effect.
Methyldopa has no direct effect on cardiac function and usually does
not reduce glomerular filtration
rate, renal blood flow, or filtration fraction. Cardiac output usually
is maintained without cardiac
acceleration. In so