Overview
DESCRIPTION Mefenamic acid is a member of the fenamate group of nonsteroidal anti-inflammatory drugs (NSAIDs). Each ivory capsule contains 250 mg of mefenamic acid for oral administration. Mefenamic acid is a white to greyish-white, odorless, microcrystalline powder with a melting point of 230° to 231°C and water solubility of 0.004% at pH 7.1. The chemical name is N-2,3-xylylanthranilic acid.
Mechanism of Action
CLINICAL PHARMACOLOGY Mechanism of Action Mefenamic acid has analgesic, anti-inflammatory, and antipyretic properties. The mechanism of action of mefenamic acid, like that of other NSAIDs, is not completely understood but involves inhibition of cyclooxygenase (COX-1 and COX-2). Mefenamic acid is a potent inhibitor of prostaglandin synthesis in vitro. Mefenamic acid concentrations reached during therapy have produced in vivo effects. Prostaglandins sensitize afferent nerves and potentiate the action of bradykinin in inducing pain in animal models. Prostaglandins are mediators of inflammation. Because mefenamic acid is an inhibitor of prostaglandin synthesis, its mode of action may be due to a decrease of prostaglandins in peripheral tissues.
Indications
- INDICATIONS AND USAGE Carefully consider the potential benefits and risks of mefenamic acid capsules and other treatment options before deciding to use mefenamic acid capsules. Use the lowest effective dose for the shortest duration consistent with individual patient treatment goals (see WARNINGS ; Gastrointestinal Bleeding, Ulceration, and Perforation ). Mefenamic acid capsules are indicated: For relief of mild to moderate pain in patients ≥14 years of age, when therapy will not exceed one week (7 days). For treatment of primary dysmenorrhea.
Common Doses
- 500 mg
- 250 mg
Dosage
DOSAGE AND ADMINISTRATION Carefully consider the potential benefits and risks of mefenamic acid and other treatment options before deciding to use mefenamic acid. Use the lowest effective dose for the shortest duration consistent with individual patient treatment goals (see Warnings ; Gastrointestinal Bleeding, Ulceration, and Perforation ). After observing the response to initial therapy with mefenamic acid, the dose and frequency should be adjusted to suit an individual patient's needs.
Black Box Warning
WARNING: RISK OF SERIOUS CARDIOVASCULAR AND GASTROINTESTINAL EVENTS Cardiovascular Thrombotic Events Nonsteroidal anti-inflammatory drugs (NSAIDs) cause an increased risk of serious cardiovascular thrombotic events, including myocardial infarction and stroke, which can be fatal. This risk may occur early in treatment and may increase with duration of use. (see Warnings ). Mefenamic acid is contraindicated in the setting of coronary artery bypass graft (CABG) surgery (see Contraindications , Warnings ).
Contraindications
- CONTRAINDICATIONS Mefenamic acid capsules are contraindicated in the following patients: Known hypersensitivity (e.g., anaphylactic reactions and serious skin reactions) to mefenamic acid or any components of the drug product (see WARNINGS ; Anaphylactic Reactions, Serious Skin Reactions ). History of asthma, urticaria, or other allergic-type reactions after taking aspirin or other NSAIDs. Severe, sometimes fatal, anaphylactic reactions to NSAIDs have been reported in such patients (see WARNINGS ; Anaphylactic Reaction, Exacerbation of Asthma Related to Aspirin Sensitivity ).
Side Effects
- ADVERSE REACTIONS The following adverse reactions are discussed in greater detail in other sections of the labeling: Cardiovascular Thrombotic Events (see Warnings ) GI Bleeding, Ulceration and Perforation (see Warnings ) Hepatotoxicity (see Warnings ) Hypertension (see Warnings ) Heart Failure and Edema (see Warnings ) Renal Toxicity and Hyperkalemia (see Warnings ) Anaphylactic Reactions (see Warnings ) Serious Skin Reactions (see Warnings ) Hematologic Toxicity (see Warnings ) Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction...
Interactions
- Drug Interactions See Table 2 for clinically significant drug interactions with mefenamic acid. $ Table 2: Clinically Significant Drug Interactions with Mefenamic Acid Drugs That Interfere with Hemostasis Clinical Impact: Mefenamic acid and anticoagulants such as warfarin have a synergistic effect on bleeding. The concomitant use of mefenamic acid and anticoagulants have an increased risk of serious bleeding compared to the use of either drug alone. Serotonin release by platelets plays an important role in hemostasis.