Indications
Cycloserine is primarily prescribed as part of a combination therapy involving up to five other medications for the treatment of infections caused by Mycobacterium avium complex (MAC) and tuberculosis (TB). Its utilization in these conditions underscores its importance in addressing challenging bacterial infections.
Pharmacodynamics
Cycloserine serves as a broad-spectrum antibiotic with the capability of acting in either a bactericidal or bacteriostatic manner, contingent on its concentration at the infection site and the susceptibility profile of the organism involved. The mechanism of action involves the inhibition of peptidoglycan synthesis, which compromises bacterial cell wall integrity, ultimately leading to bacterial cell death.
Absorption
Following oral administration, cycloserine is rapidly and nearly completely absorbed from the gastrointestinal tract, with an absorption rate ranging from 70% to 90%. This characteristic facilitates its effective delivery to systemic circulation and ensures its therapeutic potential in combating bacterial infections.
Mechanism of Action
Cycloserine is an analog of D-alanine, an amino acid critical to bacterial cell wall synthesis. It functions by competitively inhibiting two key enzymes in the cytoplasmic phase of bacterial cell wall formation. The first enzyme, L-alanine racemase, is responsible for converting L-alanine to D-alanine. The second enzyme, D-alanylalanine synthetase, plays a vital role in integrating D-alanine into the pentapeptide structure essential for peptidoglycan assembly, ultimately contributing to the formation of the bacterial cell wall. Through this mechanism, cycloserine effectively disrupts the integrity of bacterial cell walls.
