Cycloserine

Not to be confused with Cyclosarin.

Cycloserine

File:Cycloserine.svg
Systematic (IUPAC) name
(R)-4-amino-1,2-oxazolidin-3-one
Clinical data
Pregnancy category	C
Pharmacokinetic data
Bioavailability	~70% to 90%
Metabolism	Hepatic
Identifiers
CAS Number	68-41-7
ATC code	J04AB01 (WHO)
PubChem	CID 6234
DrugBank	APRD00894
ChemSpider	5998
Chemical data
Formula	C3H6N2O2
Molar mass	102.092 g/mol[[]]
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Cycloserine is an antibiotic effective against Mycobacterium tuberculosis. For the treatment of tuberculosis, it is classified as a second line drug, i.e. its use is only considered if one or more first line drugs cannot be used.

Although in principle active against other bacteria as well, cycloserine is not commonly used in the treatment of infections other than tuberculosis.

Mode of action

The terminal two amino acid residues of the murein precursor lipid II consist of D-alanine, which is produced by the enzyme alanine racemase; the two residues are joined by D-alanine ligase. Both enzymes are competitively inhibited by cycloserine.

Applications and side effects unrelated to antibiotic activity

It is also being trialed as an adjuvant to exposure therapy for anxiety disorders (e.g. phobias), depression, obsessive-compulsive disorder and schizophrenia. It has been experimentally used for treatment of Gaucher's disease.

Recent research suggests that D-cycloserine (d-4-amino-3-isoxazolidone) may be effective in treating chronic pain.

The side effects are mainly central nervous system (CNS) manifestations, i.e. headache, irritability, depression, psychosis convulsions. Co-administration of pyridoxine can reduce the incidence of some of the CNS side effects (e.g. convulsions).

These psychotropic responses are related to D-cycloserine's action as a partial agonist of the neuronal NMDA receptor for glutamate and have been examined in implications with sensory-related fear extinction in the amygdala.

References

de:Cycloserin sr:Cikloserin