METHYLDOPA tablet film coated

País: Estats Units

Idioma: anglès

Font: NLM (National Library of Medicine)

ingredients actius:

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

Disponible des:

Bryant Ranch Prepack

Designació comuna internacional (DCI):

METHYLDOPA

Composición:

METHYLDOPA ANHYDROUS 500 mg

tipo de receta:

PRESCRIPTION DRUG

Estat d'Autorització:

Abbreviated New Drug Application

Fitxa tècnica

METHYLDOPA- METHYLDOPA TABLET, FILM COATED
BRYANT RANCH PREPACK
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METHYLDOPA TABLETS, USP
RX ONLY
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 125 mg, 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
, 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: pregelatinized
starch, sodium starch glycolate,
povidone, microcrystalline cellulose, magnesium stearate,
hypromellose, FD&C yellow #6 lake and
titanium dioxide. In addition 125 mg and 250 mg tablets contain corn
starch.
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