Mefenamic acid

Mefenamic acid is an active substance of the group of non-steroidal anti-inflammatory drugs (NSAIDs). It is used for the symptomatic treatment of joint and muscle pain, rheumatic diseases, menstrual pain, swelling and inflammation after surgery and for spinal pain. In rare cases, it can also be used to reduce fever. The main dosage forms available are capsules and tablets.

Mefenamic acid is available without prescription in Switzerland and Austria. In Germany, mefenamic acid is not approved.

Pharmacodynamics

Mefenamic acid is a derivative of anthranilic acid with antipyretic, analgesic and antiphlogistic properties. It binds to both cyclooxygenase 1 and 2 enzymes, preventing the synthesis of prostaglandins and thromboxanes. Prostaglandins play an important role in the development of pain and inflammatory processes in the body. If fewer prostaglandins are now produced, there is a reduction in pain and fever.

Pharmacokinetics

Mefenamic acid is rapidly absorbed into the circulation after oral administration and approximately 90% is bound by plasma proteins. The plasma half-life is 2 hours. The drug is degraded by the liver enzyme CYP2C9 to 3-hydroxymethyl-mefenamic acid and is then conjugated to the substance glucuronic acid. Mefenamic acid is preferentially excreted in the urine, 20% of the substance is excreted in the stool.

Possible overdose symptoms are severe abdominal pain, discoloration of stools, tinnitus, muscle weakness, changes in heart rate, shallow breathing, confusion, headache, and loss of consciousness.

Taking it with alcohol can cause serious adverse side effects.

Common side effects

The most common adverse reactions include nausea and vomiting, gastrointestinal distress, loss of appetite, and various blood count changes.

Toxicological Data:

Oral, rat LD50: 740 mg/kg.