METHOCARBAMOL tablet

Country: United States

Language: English

Source: NLM (National Library of Medicine)

Active ingredient:

METHOCARBAMOL (UNII: 125OD7737X) (METHOCARBAMOL - UNII:125OD7737X)

Available from:

Watson Laboratories, Inc.

INN (International Name):

METHOCARBAMOL

Composition:

METHOCARBAMOL 500 mg

Prescription type:

PRESCRIPTION DRUG

Authorization status:

Abbreviated New Drug Application

Summary of Product characteristics

METHOCARBAMOL- METHOCARBAMOL TABLET
ACTAVIS PHARMA, INC.
----------
METHOCARBAMOL TABLETS USP
REVISED: SEPTEMBER 2008
RX ONLY
173752
RX ONLY
DESCRIPTION
Methocarbamol, a carbamate derivative of gualfenesin, is a central
nervous system (CNS) depressant
with sedative and musculoskeletal relaxant properties.
The chemical name of methocarbamol is a 3-(2
methoxyphenoxy)-1,2-propanediol 1-carbamate. The
structural formula is shown below:
STRUCTURAL FORMULA OF METHOCARBAMOL
C
H NO M.W. 241.24
Methocarbamol is a white powder, sparingly soluble in water and
chloroform, soluble in alcohol (only
with heating) and propylene glycol, and insoluble in benzene and
_n_-hexane.
Methocarbamol Tablets USP 500 mg and 750 mg, contain the follwing
inactive ingredients: colloidal
silicon dioxide, magnesium stearate, pregelatinized starch, sodium
starch glycolate and stearic acid.
CLINICAL PHARMACOLOGY
The mechanism of action of methocarbamol in humans has not been
established, but may be due to
general central nervous system (CNS) depression. It has no direct
action on the contractile mechanism
of striated muscle, the motor end plate or the nerve fiber.
PHARMACOKINETICS
In healthy volunteers, the plasma clearance of methocarbamol ranges
between 0.20 and 0.80 L/h/kg, the
mean plasma elimination half-life ranges between 1 and 2 hours, and
the plasma protein binding ranges
between 46% and 50%.
Methocarbamol is metabolized via dealkylation and hydroxylation.
Conjugation of methocarbamol also
is likely. Essentially all methocarbamol metabolites are eliminated in
the urine. Small amounts of
unchanged methocarbamol also are excreted in the urine.
11
15
5
SPECIAL POPULATIONS
_Elderly_
The mean (± SD) elimination half-life of methocarbamol in elderly
healthy volunteers (mean (± SD) age,
69 (± 4) years) was slightly prolonged compared to a younger (mean
(± SD) age, 53.3 (± 8.8) years),
healthy population (1.5 (± 0.4) hours versus 1.1 (± 0.27) hours,
respectively). The fraction of bound
methocarbamol was slightly decreased in the elderly ve