Trade Names / Brands of Mefenamic Acid in Kenya
Mefan®, Biodeal Laboratories Ltd
Mefex®, Neopharma L.L.C
Mefril®, Micro Labs Ltd
Mefsun®, Sunrise Remedies Pvt. Ltd
Meftal®, Blue Cross Laboratories Ltd
Ponstan forte®,Pfizer Laboratories Limited
MODE OF ACTION OF MEFENAMIC ACID
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).
INDICATIONS
- 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.
DOSAGE AND ADMINISTRATION
For the relief of acute pain in adults and adolescents ≥14 years of age, the recommended dose is 500 mg as an initial dose followed by 250 mg every 6 hours as needed, usually not to exceed one week.
For the treatment of primary dysmenorrhea, the recommended dose is 500 mg as an initial dose followed by 250 mg every 6 hours, given orally, starting with the onset of bleeding and associated symptoms. Clinical studies indicate that effective treatment can be initiated with the start of menses and should not be necessary for more than 2 to 3 days.
CONTRAINDICATIONS
- Hypersensitivity to mefenamic acid or any of the other ingredients.
- Inflammatory bowel disease
- History of gastrointestinal bleeding or perforation, related to previous NSAIDs therapy.
- Active, or history of recurrent peptic ulcer/haemorrhage (two or more distinct episodes of proven ulceration or bleeding).
- Severe heart failure, hepatic failure and renal failure.
- Because the potential exists for cross-sensitivity to aspirin, ibuprofen, or other non-steroidal anti-inflammatory drugs, mefenamic acid must not be given to patients who have previously shown hypersensitivity reaction (e.g. asthma, bronchospasm, rhinitis, angioedema or urticaria) to these medicines.
- During the last trimester of pregnancy .
- Treatment of pain after coronary artery bypass graft (CABG) surgery.
DRUG INTERACTIONS
Concurrent therapy with other plasma protein binding drugs may necessitate a modification in dosage.
Anti-coagulants: NSAIDs may enhance the effects of anti-coagulants, such as warfarin . Concurrent administration of mefenamic acid with oral anti-coagulant drugs requires careful prothrombin time monitoring.
It is considered unsafe to take NSAIDs in combination with Warfarin or Heparin unless under direct medical supervision.
Lithium: a reduction in renal lithium clearance and elevation of plasma lithium levels. Patients should be observed carefully for signs of lithium toxicity.
The following interactions have been reported with NSAIDs but have not necessarily been associated with mefenamic Acid :
Other analgesics including cyclooxygenase-2 selective inhibitors: avoid concomitant use of two or more NSAIDs (including aspirin) as this may increase the risk of adverse effects.
Antidepressants: selective serotonin reuptake inhibitors (SSRIs): increased risk of gastrointestinal bleeding.
Antihypertensives and diuretics: a reduction in antihypertensive and diuretic effect has been observed. Diuretics can increase the nephrotoxicity of NSAIDs.
ACE inhibitors and angiotensin-II-receptor antagonists: a reduction in antihypertensive effect and an increased risk of renal impairment especially in elderly patients. Patients should be adequately hydrated and the renal function assessed in the beginning and during concomitant therapy.
Aminoglycosides: reduction in renal function in susceptible individuals, decreased elimination of aminoglycoside and increased plasma concentrations.
Anti-platelet agents: increased risk of gastrointestinal ulceration or bleeding .
Acetylsalicylic Acid: experimental data implies that mefenamic acid interferes with the anti-platelet effect of low-dose aspirin when given concomitantly, and thus may interfere with aspirin’s prophylactic treatment of cardiovascular disease. However, the limitations of this experimental data and the uncertainties regarding extrapolation of ex vivo data to the clinical situation imply that no firm conclusions can be made for regular mefenamic acid use.
Cardiac glycosides: NSAIDs may exacerbate cardiac failure, reduce GFR and increase plasma cardiac glycoside levels.
Ciclosporin: the risk of nephrotoxicity of ciclosporin may be increased with NSAIDs.
Corticosteroids: increased the risk of gastrointestinal ulceration or bleeding (see section 4.4).
Oral hypoglycaemic agents: inhibition of metabolism of sulfonylurea drugs, prolonged half-life and increased risk of hypoglycaemia.
Methotrexate: elimination of the drug can be reduced, resulting in increased plasma levels.
Mifepristone: NSAIDs should not be taken for 8-12 days after mifepristone administration, NSAIDs can reduce the effects of mifepristone.
Probenecid: reduction in metabolism and elimination of NSAIDs and metabolites.
Quinolone antibiotics: animal data indicates that NSAIDs can increase the risk of convulsions associated with quinolone antibiotics. Patients taking NSAIDs and quinolones may have an increased risk of developing convulsions.
Tacrolimus: possible increased risk of nephrotoxicity when NSAIDS are given with tacrolimus.
Zidovudine: increased risk of haematological toxicity when NSAIDs are given with zidovudine. There is evidence of an increased risk of haemarthroses and haematoma in HIV(+) haemaophiliacs receiving concurrent treatment with zidovudine and ibuprofen.
ADVERSE EFFECTS
The most frequently reported side effects associated with mefenamic acid involve the gastrointestinal tract.
Diarrhoea occasionally occurs following the use of mefenamic acid. Although this may occur soon after starting treatment, it may also occur after several months of continuous use. The diarrhoea has been investigated in some patients who have continued this drug in spite of its continued presence. These patients were found to have associated proctocolitis. If diarrhoea does develop the drug should be withdrawn immediately and this patient should not receive mefenamic acid again.
Frequencies are not known for the following adverse reactions:
Blood and the lymphatic system disorders
Haemolytic anaemia, anaemia, hypoplasia bone marrow, haematocrit decreased, thrombocytopenic purpura, temporary lowering of the white blood cell count (leukopenia) with a risk of infection, sepsis, and disseminated intravascular coagulation.
Agranulocytosis, aplastic anaemia, eosinophilia, neutropenia, pancytopenia, thrombocytopenia.
Immune system disorders
Hypersensitivity reactions have been reported following treatment with NSAIDs. These may consist of (a) non-specific allergic reactions and anaphylaxis (b) respiratory tract reactivity comprising asthma, aggravated asthma, bronchospasm, or dyspnoea or (c) assorted skin disorders including rashes of various types, pruritus, urticaria, purpura, angioedema, and more rarely exfoliative or bullous dermatoses (including epidermal necrolysis and erythema multiforme).
Metabolism and nutritional disorders
Glucose intolerance in diabetic patients, hyponatraemia.
Pyschiatric disorders
Confusion, depression, hallucinations, nervousness.
Nervous system disorders
Optic neuritis, headaches, paraesthesia, dizziness, drowsiness, reports of aseptic meningitis (especially in patients with existing auto-immune disorders, such as systemic lupus erythematosus, mixed connective tissue disease), with symptoms such as stiff neck, headache, nausea, vomiting, fever or disorientation.
Blurred vision, convulsions, insomnia.
Eye disorders
Eye irritation, reversible loss of colour vision, visual disturbances.
Ear and labyrinth disorders
Ear pain, tinnitus, vertigo.
Cardiac / Vascular disorders
Oedema, hypertension and cardiac failure have been reported in association with NSAID treatment.
Clinical trial and epidemiological data suggest that use of some NSAIDs (particularly at high doses and in long term treatment) may be associated with an increased risk of arterial thrombotic events (for example myocardial infarction or stroke).
Palpitations.
Hypotension.
Respiratory, thoracic and mediastinal disorders
Asthma, dyspnoea.
Gastrointestinal disorders
The most commonly observed adverse events are gastrointestinal in nature. Peptic ulcers, perforation or GI bleeding, sometimes fatal, particularly in the elderly, may occur . Nausea, vomiting, diarrhoea, flatulence, constipation, dyspepsia, abdominal pain, melaena, haematemesis, ulcerative stomatitis, exacerbation of colitis and Crohn’s disease have been reported following administration. Less frequently, gastritis has been observed.
Elderly or debilitated patients seem to tolerate gastrointestinal ulceration or bleeding less well than other individuals and most spontaneous reports of fatal GI events are in this population.
Anorexia, colitis, enterocolitis, gastric ulceration with or without haemorrhage, pancreatitis, steatorrhea.
Hepato-bilary disorders
Borderline elevations of one or more liver function tests, cholestatic jaundice.
Mild hepatotoxicity, hepatitis, hepatorenal syndrome.
Skin and subcutaneous tissue disorders
Angioedema, laryngeal oedema, erythema multiforme, face oedema, bullous reactions including Lyell’s syndrome (toxic epidermal necrolysis) and Stevens-Johnson syndrome, perspiration, rash, photosensitivity reaction, pruritus and urticaria.
Renal and urinary disorders
Allergic glomerulonephritis, acute interstitial nephritis, dysuria, haematuria, nephrotic syndrome, non-oliguric renal failure (particularly in dehydration), proteinuria, renal failure including renal papillary necrosis.
General disorders
Fatigue, malaise, multi-organ failure, pyrexia.
Investigations
A positive reaction in certain tests for bile in the urine of patients receiving Mefenamic acid has been demonstrated to be due to the presence of the drug and its metabolites and not to the presence of bile.
Reporting of suspected adverse reactions:
The PPB Department of Pharmacovigilance was set up with a vision to develop, implement and continuously upgrade an appropriate system for detecting, reporting and monitoring adverse drug reactions (ADRs) and other relevant problems with medicines in Kenya. The department strives to ensure the safety and efficacy of pharmaceutical products in Kenya.
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals/ Patients are encouraged to report any suspected adverse reactions via Pharmacovigilance Yellow Form, pv@pharmacyboardkenya.org or clicking below button:
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Clinical | Pharmacokinetic data
Pregnancy Category: C
Routes of Administration: Oral
Bioavailability: 90%
Protein Binding: 90%
Metabolosim: Hepatic (CYP2C9)
Onset of Action: Not Available
Elimination Half life: 2 hours
Excretion: Urine (66%), faeces (20-25%)
Legal Status | Dosage forms & Strengths
Prescription Category:
POM (Prescription only)
Narcotic Drugs and Psychotropic Substances (Control ) Act Schedule:
This drug is not a controlled substance under Narcotic Drugs and Psychotropic Substances (Control ) Act
Dosage Forms | Strengths:
Tablets, Capsules : 250mg , 500mg
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Drug Images
References/ Citation:
- PPB Drugs Retention Register
- Bonnar, John, and Brian L. Sheppard. “Treatment of menorrhagia during menstruation: randomised controlled trial of ethamsylate, mefenamic acid, and tranexamic acid.” 313.7057 (1996): 579-582.
- Budoff, Penny Wise. “Use of mefenamic acid in the treatment of primary dysmenorrhea.” JAMA 241.25 (1979): 2713-2716.