Ethambutol is a bacteriostatic antimycobacterial

Antimycobacterial

An antimycobacterial is a type of drug used to treat Mycobacteria infections.Types include:* Tuberculosis treatments* Leprostatic agents...

 drug

Drug

A drug, broadly speaking, is any substance that, when absorbed into the body of a living organism, alters normal bodily function. There is no single, precise definition, as there are different meanings in drug control law, government regulations, medicine, and colloquial usage.In pharmacology, a...

 prescribed to treat tuberculosis

Tuberculosis

Tuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...

. It is usually given in combination with other tuberculosis drugs

Tuberculosis treatment

Tuberculosis treatment refers to the medical treatment of the infectious disease tuberculosis .The standard "short" course treatment for TB is isoniazid, rifampicin , pyrazinamide, and ethambutol for two months, then isoniazid and rifampicin alone for a further four months...

, such as isoniazid

Isoniazid

Isoniazid , also known as isonicotinylhydrazine , is an organic compound that is the first-line antituberculosis medication in prevention and treatment. It was first discovered in 1912, and later in 1951 it was found to be effective against tuberculosis by inhibiting its mycolic acid...

, rifampicin

Rifampicin

Rifampicin or rifampin is a bactericidal antibiotic drug of the rifamycin group. It is a semisynthetic compound derived from Amycolatopsis rifamycinica ...

 and pyrazinamide

Pyrazinamide

Pyrazinamide is a drug used to treat tuberculosis. The drug is largely bacteriostatic, but can be bacteriocidal on actively replicating tuberculosis bacteria.-Abbreviations:...

.

It is sold under the trade names Myambutol and Servambutol.

Adverse effects

• Optic neuritis
  Optic neuritis
  Optic neuritis is the inflammation of the optic nerve that may cause a complete or partial loss of vision.-Causes:The optic nerve comprises axons that emerge from the retina of the eye and carry visual information to the primary visual nuclei, most of which is relayed to the occipital cortex of the...
  
  . Hence contraindicated in children below 6 yrs of age.
• Red-green color blindness
• Peripheral neuropathy
  Peripheral neuropathy
  Peripheral neuropathy is the term for damage to nerves of the peripheral nervous system, which may be caused either by diseases of or trauma to the nerve or the side-effects of systemic illness....
  
  
• Arthralgia
  Arthralgia
  Arthralgia literally means joint pain; it is a symptom of injury, infection, illnesses or an allergic reaction to medication....
  
  
• Hyperuricaemia
• vertical nystagmus
• milk skin reaction

Mechanism of action

Ethambutol is bacteriostatic against actively growing TB bacilli. It works by obstructing the formation of cell wall

Cell wall

The cell wall is the tough, usually flexible but sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism. A major function of the cell wall is to...

. Mycolic acid

Mycolic acid

Mycolic acids are long fatty acids found in the cell walls of the mycolata taxon, a group of bacteria that includes Mycobacterium tuberculosis, the causative agent of the disease tuberculosis. They form the major component of the cell wall of mycolata species...

s attach to the 5'-hydroxyl groups of D-arabinose residues of arabinogalactan

Arabinogalactan

Arabinogalactan is a biopolymer consisting of arabinose and galactose monosaccharides. Two classes of arabinogalactans are found in nature: plant arabinogalactan and microbial arabinogalactan. In plants, it is a major constituent of many gums, including gum arabic, gum gutti and so on...

 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

Gastrointestinal tract

The human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....

and well distributed in body tissues and fluids, 50% is excreted unchanged in urine..

External links

• Medline Plus drug information