indication

Used in combination with up to 5 other drugs as a treatment for Mycobacterium avium complex (MAC) and is also used to treat tuberculosis (TB).

pharmacology

Cycloserine, a broad-spectrum antibiotic, may be bactericidal or bacteriostatic, depending on its concentration at the site of infection and the susceptibility of the organism. Cycloserine works by blocking the formation of these peptidoglycans. By doing this the walls of the bacteria become weak and it results in the death of the bacteria

mechanism of action

Cycloserine is an analog of the amino acid D-alanine. It interferes with an early step in bacterial cell wall synthesis in the cytoplasm by competitive inhibition of two enzymes, L-alanine racemase, which forms D-alanine from L-alanine, and D-alanylalanine synthetase, which incorporates D-alanine into the pentapeptide necessary for peptidoglycan formation and bacterial cell wall synthesis.

toxicity

Oral LD₅₀ in mouse is 5290 mg/kg, and in rat is over 5000 mg/kg. Symptoms of a cycloserine overdose include drowsiness, confusion, headache, dizziness, irritability, numbness and tingling, difficulty speaking, paralysis, abnormal behavior, seizures, and unconsciousness.

absorption

Rapidly and almost completely absorbed (70 to 90%) from the gastrointestinal tract following oral administration.

half life

Half-life in patients with normal renal function is 10 hours, and is prolonged in patients with impaired renal function.