Molecule

Drug Groups

approved

Description

A non-steroidal anti-inflammatory agent with antipyretic and antigranulation activities. It also inhibits prostaglandin biosynthesis. [PubChem]

Indication

For the relief of mild to moderate pain, for the treatment of primary dysmenorrhea and for the treatment of idiopathic heavy menstrual blood loss. Also for relief of the signs and symptoms of acute and chronic rheumatoid arthritis and osteoarthritis.

Pharmacology

Meclofenamic acid is a nonsteroidal agent which has demonstrated anti-inflammatory, analgesic, and antipyretic activity in laboratory animals.

Toxicity

After a massive overdose, CNS stimulation may be manifested by irrational behavior, marked agitation and generalized seizures. Following this phase, renal toxicity (falling urine output, rising creatinine, abnormal urinary cellular elements) may be noted with possible oliguria or anuria and azotemia. A 24 year-old male was anuric for approximately one week after ingesting an overdose of 6 to 7 grams of meclofenamate sodium. Spontaneous diuresis and recovery subsequently occurred.

Affected Organisms

Biotransformation

Hepatic. Meclofenamic acid is extensively metabolized to an active metabolite (Metabolite I; 3-hydroxymethyl metabolite of meclofenamic acid) and at least six other less well characterized minor metabolites. Only Metabolite I has been shown in vitro to inhibit cyclooxygenase activity with approximately one fifth the activity of meclofenamic acid.

Absorption

Rapidly absorbed in man following single and multiple oral doses with peak plasma concentrations occurring in 0.5 to 2 hours. The concomitant administration of antacids (aluminum and magnesium hydroxides) does not interfere with absorption of meclofenamic acid. Unlike most NSAIDs, which when administered with food have a decrease in rate but not in extent of absorption, meclofenamic acid is decreased in both. It has been reported that following the administration of meclofenamic acid capsules one-half hour after a meal, the average extent of bioavailability decreased by 26%, the average peak concentration (C_max) decreased fourfold and the time to C_max was delayed by 3 hours.

Half Life

In a study in 10 healthy subjects following a single oral dose the apparent elimination half-life ranged from 0.8 to 5.3 hours. Metabolite I (3-hydroxymethyl metabolite of meclofenamic acid) has a mean half-life of approximately 15 hours.

Protein Binding

Greater than 99% bound to plasma proteins over a wide drug concentration range.

Elimination

Other metabolites, whose excretion rates are unknown, account for the remaining 35% to 62% of the dose excreted in the urine. The remainder of the administered dose (approximately 30%) is eliminated in the feces (apparently through biliary excretion). Trace amounts of meclofenamate sodium are excreted in human breast milk.

Distribution

* 9.1 to 43.2 L

Clearance

* Oral cl=206 mL/min

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