Adult: In combination with other antituberculars (e.g. isoniazid, pyrazinamide, rifampicin): For prophylaxis and primary treatment: 15 mg/kg once daily. For re-treatment: 25 mg/kg once daily for 60 days; then, 15 mg/kg once daily. Recommended Max dose: 1.6 g daily (regardless of weight). For more information (e.g. alternative regimens), consult product literature. Child: In combination with other antituberculars (e.g. isoniazid, pyrazinamide, rifampicin): For prophylaxis: 15 mg/kg once daily. For primary treatment and re-treatment: 25 mg/kg once daily for 60 days; then, 15 mg/kg once daily. For more information (e.g. alternative regimens), consult product literature.
Renal Impairment
Reduce dose based on serum-ethambutol levels. Alternatively, for patients with CrCl <30 mL/min, 15 mg/kg 3 times weekly or 15-25 mg/kg (depending on serum-ethambutol levels), to a Max of 2.5 g 3 times weekly.
Administration
Should be taken with food.
Contraindications
Hypersensitivity. Optic and retrobulbar neuritis. Inability to report visual disturbances (e.g. unconscious).
Special Precautions
Patient with ocular disease (e.g. ocular inflammatory conditions, cataracts, diabetic retinopathy). Renal impairment. Children. Pregnancy and lactation.
Adverse Reactions
Significant: Optic neuritis, visual disturbances (e.g. colour blindness and irreversible blindness). Blood and lymphatic system disorders: Thrombocytopenia, eosinophilia, leucopenia, neutropenia. Gastrointestinal disorders: Nausea, vomiting, abdominal pain, gastrointestinal upset. General disorders and administration site conditions: Malaise, fever. Hepatobiliary disorders: Jaundice. Immune system disorders: Hypersensitivity reactions, erythema multiforme. Investigations: Hyperuricaemia. Metabolism and nutrition disorders: Anorexia. Musculoskeletal and connective tissue disorders: Acute gout. Nervous system disorders: Headache, dizziness, peripheral neuropathy. Psychiatric disorders: Confusion, disorientation, hallucinations. Respiratory, thoracic and mediastinal disorders: Pulmonary infiltrates. Skin and subcutaneous tissue disorders: Dermatitis, erythema multiforme, pruritus. Potentially Fatal: Hepatotoxicity.
This drug may cause visual disturbances, if affected, do not drive or operate machinery.
Monitoring Parameters
Determine at baseline and monitor (monthly) visual and colour discrimination test results. Monitor LFT and renal function (at baseline and during therapy); other signs and symptoms of visual disturbances. Perform haematopoietic tests.
Description: Mechanism of Action: Ethambutol, an antimycobacterial, is bacteriostatic against susceptible bacteria. It appears to inhibit synthesis of bacterial metabolites thereby, inhibiting cellular metabolism and multiplication. Pharmacokinetics: Absorption: Absorbed from the gastrointestinal tract. Time to peak plasma concentration: Within 4 hours. Distribution: Distributed to most tissues, including kidneys, lungs, and erythrocytes. Crosses the placenta and enters breastmilk. Plasma protein binding: 20-30%. Metabolism: Partially metabolised in the liver into inactive aldehyde and dicarboxylic acid derivatives. Excretion: Mainly via urine (approx 50% as unchanged drug and 8-15% as metabolites); faeces (approx 20% as unchanged drug). Elimination half-life: Approx 2.5-3.6 hours.
Chemical Structure
Ethambutol Source: National Center for Biotechnology Information. PubChem Database. Ethambutol Hydrochloride, CID=14052, https://pubchem.ncbi.nlm.nih.gov/compound/Ethambutol-Hydrochloride (accessed on Jan. 23, 2020)
J04AK02 - ethambutol ; Belongs to the class of other drugs used in the systemic treatment of tuberculosis.
References
Anon. Ethambutol. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 04/07/2018.Anon. Ethambutol. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 04/07/2018.Buckingham R (ed). Ethambutol Hydrochloride. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/07/2018.Ethambutol Hydrochloride Tablet, Film Coated (STI Pharma LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 04/07/2018.Joint Formulary Committee. Ethambutol Hydrochloride. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 04/07/2018.McEvoy GK, Snow EK, Miller J et al (eds). Ethambutol Hydrochloride. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 19/08/2014.
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