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Ethambutol

Chemical structure of ethambutol (top) and photo of ethambutol crystals (bottom)
Clinical data
Trade names	Myambutol, Etibi, Servambutol, others
Other names	(2S,2’S)-2,2’-(Ethane-1,2-diyldiimino)dibutan-1-ol
AHFS/Drugs.com	Monograph
License data	US DailyMed: Ethambutol
Routes of administration	By mouth
ATC code	J04AK02 (WHO)
Legal status
Legal status	AU: S4 (Prescription only) In general: ℞ (Prescription only)
Pharmacokinetic data
Protein binding	20–30%
Metabolism	liver
Elimination half-life	3–4 hours
Identifiers
CAS Number	74-55-5
PubChem CID	14052
DrugBank	DB00330
ChemSpider	13433
UNII	8G167061QZ
KEGG	D07925
ChEBI	CHEBI:4877
ChEMBL	ChEMBL44884
CompTox Dashboard (EPA)	DTXSID8023006
ECHA InfoCard	100.000.737
Chemical and physical data
Formula	C10H24N2O2
Molar mass	204.314 g·mol
3D model (JSmol)	Interactive image
SMILES CC(CO)NCCN(CC)CO
InChI InChI=1S/C10H24N2O2/c1-3-9(7-13)11-5-6-12-10(4-2)8-14/h9-14H,3-8H2,1-2H3/t9-,10-/m0/s1 Key:AEUTYOVWOVBAKS-UWVGGRQHSA-N

Ethambutol (EMB, E) is a medication primarily used to treat tuberculosis. It is usually given in combination with other tuberculosis medications, such as isoniazid, rifampicin and pyrazinamide. It may also be used to treat Mycobacterium avium complex, and Mycobacterium kansasii. It is taken by mouth.

Common side effects include problems with vision, joint pain, nausea, headaches, and feeling tired. Other side effects include liver problems and allergic reactions. It is not recommended in people with optic neuritis, significant kidney problems, or under the age of five. Use during pregnancy or breastfeeding has not been found to cause harm. In the United States the FDA has raised concerns about eye issues in the baby if used during pregnancy. Ethambutol is believed to work by interfering with the bacteria's metabolism.

Ethambutol was discovered in 1961. It is on the World Health Organization's List of Essential Medicines and is available as a generic medication.

Chirality and biological activity

(S,S)-(+)-Ethambutol is powerful and selective antitubercular drug. It is a typical example of an old drug that was introduced for clinical use in its unichiral form. Ethambutol contains two constitutionally symmetrical chiral centers in its structure and exists in three stereoisomeric forms, the enantiomeric pair (+)-(S,S)- and (−)-(R,R)-ethambutol, along with the achiral stereoisomer called meso-form. The (+)-(S,S)-enantiomer harbors the antitubercular activity. This enantiomer is 500 and 12 fold more potent than (−)-(R,R)-ethambutol and the meso-form respectively. On the other hand, all the three isomers are equipotent in terms of the major side-effect of the drug, optic neuritis. Toxicity is associated to both dose and duration of treatment. Hence the use of (S,S)-enantiomer greatly improved the risk/benefit balance.

Medical uses

Ethambutol is used along with other medications to treat a number of infections including: tuberculosis, Mycobacterium avium complex, and Mycobacterium kansasii.

Adverse effects

• Optic neuritis (hence contraindicated in children below six years of age)
• Red–green color blindness People taking ethambutol should be monitored for changes in visual acuity and color discrimination.
• Arthralgia
• Hyperuricaemia
• Vertical nystagmus
• Skin rash

Mechanism of action

Ethambutol is bacteriostatic against actively growing TB bacilli. It works by obstructing the formation of cell wall. Mycolic acids attach to the 5'-hydroxyl groups of D-arabinose residues of arabinogalactan and form mycolyl-arabinogalactan-peptidoglycan complex in the cell wall. It disrupts arabinogalactan synthesis by inhibiting the enzyme arabinosyl transferase. Disruption of the arabinogalactan synthesis inhibits the formation of this complex and leads to increased permeability of the cell wall.

Pharmacokinetics

It is well absorbed from the gastrointestinal tract and well distributed in body tissues and fluids. 50% is excreted unchanged in urine.

See also

• Chiral drugs
• Chirality
• Enantiopure drug
• Stereochemistry

References

1. ^ Hamilton R (2015). Tarascon Pocket Pharmacopoeia (Deluxe Lab-Coat ed.). Jones & Bartlett Learning. p. 48. ISBN 9781284057560.
2. "ethambutol (CHEBI:4877)". Chemical Entities of Biological Interest. UK: European Bioinformatics Institute. 18 August 2010. Main. Archived from the original on 19 July 2014. Retrieved 26 April 2012 – via ebi.ac.uk.
3. "ETHAMBUTOL LUPIN, ETHAMBUTOL LAPL, ETHAMBUTOL GH (Lupin Australia Pty Limited)". Therapeutic Goods Administration (TGA). 28 September 2022. Retrieved 20 April 2023.
4. ^ "Ethambutol Hydrochloride". drugs.com. The American Society of Health-System Pharmacists. Archived from the original on 5 June 2016. Retrieved 10 December 2016.
5. ^ Stuart MC, Kouimtzi M, Hill SR, eds. (2009). WHO Model Formulary 2008. World Health Organization. pp. 136, 138, 588, 603. hdl:10665/44053. ISBN 9789241547659.
6. "Prescribing medicines in pregnancy database". TGA.gov.au. Therapeutic Goods Administration, Department of Health, Australia. 3 March 2014. Archived from the original on 8 April 2014. Retrieved 22 April 2014.
7. Landau R, Achilladelis B, Scriabine A (1999). Pharmaceutical Innovation: Revolutionizing Human Health. Chemical Heritage Foundation. p. 171. ISBN 9780941901215. Archived from the original on 2016-12-20.
8. Organization WH (2019). World Health Organization model list of essential medicines: 21st list 2019. Geneva: World Health Organization. hdl:10665/325771. WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO.
9. Sheldon RA (1993). Chirotechnology : industrial synthesis of optically active compounds. New York: Marcel Dekker. ISBN 0-8247-9143-6. OCLC 27897833.
10. Stereochemical aspects of drug action and disposition. S. K. Branch, Michel Eichelbaum, Bernard Testa, Andrew Somogyi. Berlin: Springer. 2003. ISBN 978-3-540-41593-0. OCLC 52515592.{{cite book}}: CS1 maint: others (link)
11. Kannappan V. "Ethambutol – Chiralpedia". Retrieved 2022-08-29.
12. Lim SA (April 2006). "Ethambutol-associated optic neuropathy" (PDF). Annals of the Academy of Medicine, Singapore. 35 (4): 274–8. doi:10.47102/annals-acadmedsg.V35N4p274. PMID 16710500. S2CID 12478013. Archived (PDF) from the original on 2009-08-16.
13. ^ Lewis SM, Dirksen SR, Heitkemper MM, Bucher L, Harding M (5 December 2013). Medical-surgical nursing : assessment and management of clinical problems (9th ed.). St. Louis, Missouri. ISBN 978-0-323-10089-2. OCLC 228373703.{{cite book}}: CS1 maint: location missing publisher (link)
14. Tripathi KD (August 2015). Essentials of Medical Pharmacology (Seventh ed.). India: Jaypee Brothers Medical Publishers. p. 769. ISBN 978-93-5025-937-5.
15. "Ethambutol: MedlinePlus Drug Information". medlineplus.gov. Retrieved 2023-05-17.

External links

• "Ethambutol". Medicine Plus.
• "Ethambutol". Drug Information Portal. U.S. National Library of Medicine.

• Medicine

• Anti-tuberculosis drugs
• Diamines
• Diols
• Secondary amines
• World Health Organization essential medicines
• Substances discovered in the 1960s