INSTRUCTION

for medical use of the medicinal product

MEFENAMIC ACID

Composition:

active substance: mefenamic acid;

1 capsule contains mefenamic acid 250 mg or 500 mg;

excipients:

capsules 250 mg: talc; lactose, monohydrate; corn starch; sodium lauryl sulfate; colloidal silica; magnesium stearate;

capsules 500 mg: talc, stearic acid, corn starch, sodium lauryl sulfate, crospovidone.

Pharmaceutical form. Capsules.

Basic physical and chemical properties: hard gelatin capsules, size "0", with a light-blue cap and a light-yellow body or vice versa; the content of the capsules is a white or almost white powder.

Pharmacotherapeutic group. Non-steroidal anti-inflammatory and antirheumatic agents. Fenamates.

ATC Code M01A G01.

Pharmacological properties.

Pharmacodynamics.

Non-steroidal anti-inflammatory drug (NSAID). It has anti-inflammatory, analgesic and antipyretic effects. It inhibits the synthesis of inflammatory mediators (prostaglandins, serotonin, kinins), reduces the activity of lysosomal proteases involved in the inflammatory reaction. It affects the phases of exudation and proliferation. It stabilizes protein ultrastructures and cell membranes, reduces vascular permeability and tissue swelling. It inhibits cell proliferation at the inflammation site; increases cell resistance and stimulates wound healing. The antipyretic effect is due to the inhibition of prostaglandin synthesis and an effect on the thermoregulation center. It stimulates the formation of interferon.

Pharmacokinetics.

After oral administration, it is rapidly and almost completely absorbed from the gastrointestinal tract. Maximum concentration in the blood is reached after 2-4 hours. The blood level is proportional to the dose. In the vascular bed, it binds to albumins. The elimination half-life is 3 hours. It forms several metabolites in the liver. 67% of the administered dose is excreted unchanged in the urine, 20-25% – in the feces.

Clinical characteristics.

Indications.

Acute respiratory viral infections and influenza.

Primary dysmenorrhea. Dysfunctional menorrhagia.

Inflammatory diseases of the musculoskeletal system: rheumatoid arthritis, rheumatism, ankylosing spondylitis.

Pain syndrome of low and moderate intensity: muscle, joint, traumatic, dental, headache of various etiologies, postoperative and postpartum pain.

Contraindications.

Hypersensitivity to the components of the drug. History of bronchospasm, angioedema, rhinitis, bronchial asthma or urticaria that occurred after the use of acetylsalicylic acid or other NSAIDs. Concomitant use of specific COX-2 inhibitors. Active or history of gastric and duodenal ulcer, inflammatory bowel disease, diseases of the hematopoietic organs, severe heart failure, severe hepatic or renal impairment, gastrointestinal bleeding or perforation caused by NSAIDs, treatment of pain after coronary artery bypass graft surgery.

Interaction with other medicinal products and other forms of interaction.

Thiamine, pyridoxine hydrochloride, barbiturates, phenothiazine derivatives, narcotic analgesics, caffeine, diphenhydramine increase the analgesic effect of the drug.

Methotrexate: concomitant use of mefenamic acid and methotrexate may lead to a potential increase in plasma methotrexate levels and an increase in its toxic effect.

Probenecid: decreased metabolism, delayed excretion of probenecid from the body.

Antihypertensives (ACE inhibitors and angiotensin II receptor antagonists): reduction of antihypertensive effect, increased risk of renal failure, especially in elderly patients. Patients should drink adequate fluids. Renal function should also be assessed at the beginning of treatment and during concomitant therapy.

Diuretics: reduction of diuretic effect. Diuretics may increase the nephrotoxicity of NSAIDs.

Cardiac glycosides: NSAIDs may exacerbate heart failure, reduce glomerular filtration rate and increase plasma levels of cardiac glycosides.

Cyclosporines: increased risk of nephrotoxicity.

Mifepristone: NSAIDs should not be taken for 8-12 days after mifepristone administration; NSAIDs may reduce the effect of mifepristone.

Corticosteroids: increased risk of gastrointestinal ulcers and bleeding.

Antiplatelet agents and selective serotonin reuptake inhibitors: increased risk of gastrointestinal bleeding.

Fluoroquinolones: NSAIDs increase the risk of seizures.

Aminoglycosides: NSAIDs increase the risk of nephrotoxic effect.

Tacrolimus: possible increased risk of nephrotoxic effect.

Zidovudine: NSAIDs increase the risk of haematological toxicity. There is an increased risk of haemarthrosis and hematoma in HIV-positive haemophiliacs simultaneously receiving treatment with zidovudine.

Lithium preparations: decreased lithium excretion and increased risk of lithium toxicity.

Oral anticoagulants: mefenamic acid increases the activity of oral anticoagulants, therefore, their concomitant use increases the risk of bleeding. A reduction in the anticoagulant dose may be necessary. Concomitant use of mefenamic acid with oral anticoagulants requires careful monitoring of prothrombin time. It is considered dangerous to take NSAIDs with warfarin or heparin; medical supervision is required.

Concomitant use with other non-steroidal anti-inflammatory drugs increases the anti-inflammatory effect and the likelihood of adverse gastrointestinal events.

Precautions for use.

Mefenamic acid should not be used in patients who have previously experienced hypersensitivity reactions (e.g., asthma, bronchospasm, rhinitis, angioedema, or urticaria).

Do not use in dehydrated patients who have lost fluid due to vomiting, diarrhea, or increased urination.

During long-term treatment of headache, a doctor should be consulted.

The drug should be prescribed with caution to patients with acute cardiovascular failure, arterial hypertension, and ischemic heart disease. The use of mefenamic acid may be associated with a small increase in the risk of heart attack or stroke. Any risk is associated with increasing the dose of the drug or long-term treatment. During therapy with mefenamic acid, patients with cardiovascular and cerebrovascular diseases should consult a doctor and not exceed the recommended dose or duration of treatment.

The drug should be prescribed with caution to patients with epilepsy.

Moderate impairment of liver and kidney function may occur during the use of mefenamic acid. For patients who develop such disorders, therapy with the drug should be discontinued. Patients using mefenamic acid for a long time should be monitored due to the possibility of liver and kidney dysfunction.

NSAIDs should be taken with caution by patients with a history of gastrointestinal diseases (ulcerative colitis, Crohn's disease, inflammatory bowel disease), as exacerbation of the disease is possible. If the use of mefenamic acid leads to gastrointestinal bleeding or perforation, treatment with the drug should be discontinued.

Elderly patients generally have an increased risk of adverse gastrointestinal effects, especially gastrointestinal bleeding and perforation, which can be fatal, so treatment should be started with the lowest dosage.

Patients with systemic lupus erythematosus and mixed connective tissue disorders may have an increased risk of aseptic meningitis.

Mefenamic acid should be used with caution in patients at high risk of serious skin reactions, including exfoliative dermatitis, Stevens-Johnson syndrome, and toxic epidermal necrolysis. At the first sign of skin rash, mucosal lesions, or any sign of hypersensitivity, therapy with the drug should be discontinued.

During long-term use of the drug, blood counts should be monitored, as mefenamic acid can cause pathological changes in the blood. If any signs of dyscrasia occur, therapy with the drug should be discontinued.

Taking mefenamic acid may lead to gastrointestinal disorders (e.g., diarrhea). These may occur either immediately after using the drug or after long-term use. If such symptoms occur, the use of the drug should be discontinued.

Caution should be exercised when using mefenamic acid in patients receiving concomitant therapy with drugs that may increase the risk of bleeding - corticosteroids, anticoagulants (warfarin), and aspirin.

Taking mefenamic acid may impair female fertility and is not recommended for women attempting to conceive. When used by women for symptoms of dysmenorrhea and menorrhagia and in the absence of a therapeutic effect, a doctor should be consulted.

Mefenamic acid, capsules 250 mg, contains lactose, therefore patients with rare hereditary forms of galactose intolerance, lactase deficiency or glucose-galactose malabsorption syndrome should not use the drug.

Pregnancy and lactation.

The drug should not be used for pregnant women.

Starting from the 20th week of pregnancy, the use of mefenamic acid may cause oligohydramnios due to foetal kidney dysfunction; constriction of the foetal ductus arteriosus has also been reported.

The use of any prostaglandin synthesis inhibitor during the third trimester of pregnancy may cause:

in the foetus:

• - development of cardiopulmonary toxicity (with premature constriction/closure of the ductus arteriosus and pulmonary hypertension);
• - kidney dysfunction, which may progress to renal failure with the development of oligohydramnios (see above);

in the mother and newborn, as well as at the end of pregnancy:

• - increased bleeding time, an antiplatelet effect that may occur even at low doses of the drug;
• - inhibition of uterine contractility, leading to delayed labour or prolonged labour.

The drug should not be used by women during breastfeeding.

Effects on ability to drive and use machines.

Caution should be exercised when driving or operating machinery that requires increased attention, as the use of the drug may sometimes cause drowsiness, blurred vision, or convulsions.

Method of administration and dosage.

For oral use. Take after meals.

Adults and children over 12 years of age should take 250-500 mg 3-4 times daily. If necessary, the daily dose may be increased to 3 g per day. After achieving a therapeutic effect, the daily dose should be reduced to 1 g.

The course of treatment for joint diseases may last from 20 days to 2 months or more. For the treatment of pain syndrome, the course of treatment lasts up to 7 days.

Children.

It is recommended for children over 12 years of age.

Overdose.

Symptoms: pain in the epigastric region, nausea, vomiting, drowsiness, headache, rarely – diarrhea, disorientation, agitation, tinnitus, loss of consciousness, sometimes convulsions (mefenamic acid tends to induce tonic-clonic seizures in overdose). In severe cases – gastrointestinal bleeding, respiratory depression, arterial hypertension, twitching of individual muscle groups, coma. In cases of significant poisoning, renal and hepatic failures are possible.

Treatment: No specific antidote. Gastric lavage with activated charcoal suspension. Alkalization of urine, forced diuresis. Symptomatic therapy. Haemoperfusion and haemodialysis are not very effective due to the strong binding of mefenamic acid to blood proteins. Renal and hepatic functions should be carefully monitored. Frequent or prolonged convulsions should be treated with intravenous diazepam.

Adverse reactions.

Gastrointestinal tract disorder: epigastric pain, anorexia, heartburn, nausea, flatulence, vomiting, enterocolitis, colitis, exacerbation of colitis and Crohn's disease, gastritis, hepatotoxicity, steatorrhea, cholestatic jaundice, hepatitis, pancreatitis, hepatorenal syndrome, haemorrhagic gastritis, peptic ulcer with/without bleeding, melena, ulcerative stomatitis. Gastrointestinal bleeding, dyspepsia, constipation, diarrhea; perforation or gastrointestinal bleeding, sometimes fatal, especially in elderly patients. Elevated liver enzymes in plasma.

Cardiovascular system disorder: arterial hypertension, arrhythmia, rarely – congestive heart failure, peripheral oedema, syncope, arterial hypotension, palpitations, dyspnoea, thrombotic complications (e.g., myocardial infarction or stroke).

Respiratory system disorder: dyspnoea, bronchospasm.

Urinary system disorder: dysuria, cystitis. Renal impairment, albuminuria, haematuria, oliguria or polyuria, renal failure, including papillary necrosis, acute interstitial nephritis, nephrotic syndrome, allergic glomerulonephritis, hyponatremia, hyperkalaemia.

Blood system disorder: aplastic anaemia, autoimmune haemolytic anaemia, increased bleeding time, eosinophilia, leukopenia with risk of infection, sepsis or disseminated intravascular coagulation, thrombocytopenia, decreased haematocrit, thrombocytopenic purpura, agranulocytosis, neutropenia, pancytopenia, bone marrow hypoplasia.

Nervous system and psyche disorder: drowsiness or insomnia, weakness, irritability, agitation, headache, blurred vision, convulsions, confusion, depression, hallucinations, optic neuritis, paraesthesia, dizziness, neck stiffness, fever, disorientation.

Sensory organs disorder: tinnitus, ear pain, otalgia, visual disturbances, reversible loss of colour vision, eye irritation.

Immune system disorder: purpura, hypersensitivity reactions including skin rash, pruritus, facial oedema, allergic rhinitis, angioedema, laryngeal oedema, Stevens-Johnson syndrome, toxic epidermal necrolysis, erythema multiforme, urticaria, bullous pemphigus, photosensitivity, asthma, anaphylaxis.

Other: impaired glucose tolerance in patients with diabetes mellitus, aseptic meningitis, sweating, increased fatigue, malaise, multi-organ failure, hyperthermia, positive reaction in some tests for the presence of mefenamic acid and its metabolites in bile and urine.

Shelf life. 3 years.

Storage conditions. Store in original packaging at a temperature not exceeding 30 °C. Keep out of reach of children.

Packaging.

10 capsules in a blister; 2 blisters in a box.

Terms of dispensing. No prescription.

Date of last update.

11.04.2025