SKELAXIN- metaxalone tablet

Country: United States

Language: English

Source: NLM (National Library of Medicine)

Active ingredient:

METAXALONE (UNII: 1NMA9J598Y) (METAXALONE - UNII:1NMA9J598Y)

Available from:

Pfizer Laboratories Div Pfizer Inc

Administration route:

ORAL

Prescription type:

PRESCRIPTION DRUG

Therapeutic indications:

SKELAXIN (metaxalone) is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomforts associated with acute, painful musculoskeletal conditions. The mode of action of this drug has not been clearly identified, but may be related to its sedative properties. Metaxalone does not directly relax tense skeletal muscles in man. Known hypersensitivity to any components of this product. Known tendency to drug induced, hemolytic, or other anemias. Significantly impaired renal or hepatic function.

Product summary:

SKELAXIN (metaxalone) is available as an 800 mg oval, scored pink tablet inscribed with 8667 on the scored side and "S" on the other. Available in bottles of 100 (NDC 60793-136-01) and in bottles of 500 (NDC 60793-136-05). Store at Controlled Room Temperature, between 15°C and 30°C (59°F and 86°F).

Authorization status:

New Drug Application

Summary of Product characteristics

SKELAXIN- METAXALONE TABLET
PFIZER LABORATORIES DIV PFIZER INC
----------
SKELAXIN
(METAXALONE) TABLETS
SKELAXIN TABLET
DESCRIPTION
SKELAXIN (metaxalone) is available as an 800 mg oval, scored pink
tablet.
Chemically, metaxalone is 5-[(3,5- dimethylphenoxy)
methyl]-2-oxazolidinone. The
empirical formula is C
H
NO , which corresponds to a molecular weight of 221.25.
The structural formula is:
Metaxalone is a white to almost white, odorless crystalline powder
freely soluble in
chloroform, soluble in methanol and in 96% ethanol, but practically
insoluble in ether or
water.
Each tablet contains 800 mg metaxalone and the following inactive
ingredients: alginic
acid, ammonium calcium alginate, B-Rose Liquid, corn starch, and
magnesium stearate.
CLINICAL PHARMACOLOGY
MECHANISM OF ACTION
The mechanism of action of metaxalone in humans has not been
established, but may
be due to general central nervous system (CNS) depression. Metaxalone
has no direct
action on the contractile mechanism of striated muscle, the motor end
plate, or the
nerve fiber.
PHARMACOKINETICS
The pharmacokinetics of metaxalone have been evaluated in healthy
adult volunteers
after single dose administration of SKELAXIN under fasted and fed
conditions at doses
ranging from 400 mg to 800 mg.
Absorption
Peak plasma concentrations of metaxalone occur approximately 3 hours
after a 400 mg
oral dose under fasted conditions. Thereafter, metaxalone
concentrations decline log-
linearly with a terminal half-life of 9.0 ± 4.8 hours. Doubling the
dose of SKELAXIN from
®
®
12
15
3
400 mg to 800 mg results in a roughly proportional increase in
metaxalone exposure as
indicated by peak plasma concentrations (C
) and area under the curve (AUC). Dose
proportionality at doses above 800 mg has not been studied. The
absolute bioavailability
of metaxalone is not known.
The single-dose pharmacokinetic parameters of metaxalone in two groups
of healthy
volunteers are shown in Table 1.
TABLE 1: MEAN (%CV) METAXALONE PHARMACOKINETIC
PARAMETERS
DOSE (MG)
C
(NG/ML)
T (H)
AUC
(NG