500 mg Tablet
NON-STEROIDAL ANTI-INFLAMMATORY DRUG (NSAID)

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FORMULATION:
Each tablet contains:
Mefenamic acid, USP…………………………...........................……….500 mg

PRODUCT DESCRIPTION:
Mefenamic acid (Lezpain) 500 mg tablet is an oral Non-Steroidal Anti-Inflammatory Drug. It is an off-white capsule form tablet.

PHARMACODYNAMICS:
Mefenamic acid has a Non-steroidal anti-inflammatory, analgesic, antipyretic properties. Mefenamic acid is a potent inhibitor of prostaglandin synthesis, its mode of action may be due to a decrease of prostaglandins in peripheral tissues.

PHARMACOKINETICS:
Absorption
Mefenamic acid is rapidly absorbed after oral administration. In two 500 mg single oral dose studies, the mean extent of absorption was 30.5 mcg/hr/mL (17%CV). Following a single 1 gram oral dose, mean peak plasma levels ranging from 10-20 mcg/mL have been reported. Peak plasma levels are attained in 2 to 4 hours and the elimination half-life approximates 2 hours. Following multiple doses, plasma levels are proportional to dose with no evidence of drug accumulation. The effect of food on the rate and extent of absorption of mefenamic acid has not been studied.
Distribution
Mefenamic acid has been reported as being greater than 90% bound to albumin. The relationship of unbound fraction to drug concentration has not been studied. The apparent volume of distribution estimated following a 500 mg oral dose of mefenamic acid was 1.06 L/kg.
Metabolism
Mefenamic acid is metabolized by cytochrome P450 enzyme CYP2C9 to 3-hydroxymethyl mefenamic acid. Further oxidation to a 3-carboxymefenamic acid may occur. The metabolites may undergo glucuronidation and mefenamic acid is also glucuronidated directly. A peak plasma level approximating 20 mcg/mL was observed at 3 hours for the hydroxy
metabolite and its glucuronide after a single 1 gram dose. Similarly, a peak plasma level of 8 mcg/mL was observed at 6-8 hours for the carboxy metabolite and its glucuronide.
Excretion
Approximately 52% of mefenamic acid dose is excreted into the urine. The fecal route of elimination accounts for up to 20% of the dose. The elimination half-life of mefenamic acid is approximately two hours. The metabolites may accumulate in patients with renal or hepatic failure. The mefenamic acid glucuronide may bind irreversibly to plasma proteins.

INDICATIONS:
For the relief of headache, muscular and traumatic pain, post-operative, post-extraction and post-partum pain.

DOSAGE AND ADMINISTRATION:
Take 1 tablet 3 times a day or as prescribed by the physician. Preferably taken with food.