Cycloserine
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Cycloserine
Systematic (IUPAC) name
4-aminoisoxazolidin-3-one
Identifiers
CAS number	68-41-7
ATC code	J04AB01
PubChem	401
DrugBank	APRD00894
Chemical data
Formula	C3H6N2O2
Mol. mass	102.092 g/mol
Pharmacokinetic data
Bioavailability	~70% to 90%
Metabolism	Hepatic
Half life	10 hrs (normal renal function)
Excretion	?
Therapeutic considerations
Pregnancy cat.	C
Legal status
Routes	Oral

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 for treatment of phobias^[1] as well as an adjuvant to conventional treatments for depression, obsessive-compulsive disorder and schizophrenia. It has been experimentally used for treatment of Gaucher's disease.

Recent research suggests that D-cycloserine may be effective in treating chronic pain.^[2]

The side effects are mainly central nervous system (CNS) manifestations, i.e. headache, irritability, depression, 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.^[1]

References

1. ^ ^{a b} Davis, Michael; Karyn M. Myers, Kerry J. Ressler and Barbara O. Rothbaum (2005). "Facilitation of Extinction of Conditioned Fear by D-Cycloserine". American Psychological Society 14 (4): 214–219. doi:10.1111/j.0963-7214.2005.00367.x. Retrieved on 2008-07-15. 
2. ^ "Newly Identified Drug Relieves Suffering", Science Daily (2007-06-05). Retrieved on 2008-07-15.