Cycloserine
SEROMYCIN
What it isSecond-line antituberculosis antibiotic with NMDA glycine-site partial co-agonism; drug-resistant tuberculosis.
Why this oneCross-resistance with standard tuberculosis drugs is uncommon, preserving a reserve role in multidrug regimens.
What limits itRenal accumulation increases seizures, psychosis, and suicidality; adjust for renal function, avoid alcohol, and give pyridoxine.
FDA-approved for
- tuberculosis (second-line) (1964)
FDA label
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| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Active pulmonary & extrapulmonary tuberculosis (with other antitubercular agents) | Adults | 250 mg BID (q12h) × 2 wk | 500 mg–1 g/day divided (blood-level guided) | 1 g/day |
Renal Contraindicated in severe renal insufficiency
Hepatic Undefined
Instructions
- Dose monitored by blood levels; do not exceed 1 g/day
Contraindications
- Epilepsy
- Depression, severe anxiety, or psychosis
- Severe renal insufficiency
- Excessive concurrent use of alcohol
Adverse reactions
- Convulsions/seizures
- Drowsiness, somnolence, headache, tremor, vertigo
- Confusion/disorientation with memory loss
- Psychosis, possibly with suicidal tendencies
- Skin rash (hypersensitivity)
- Elevated serum transaminases
Pregnancy Undefined
Lactation Undefined
NO BOXED WARNINGS
Principal riskseizures and severe neuropsychiatric toxicity
Cost, est. cash$10–$500/month
Generic entryPre-1982
Classes and tags
Clinical profile
Legacy pregnancy categoryUnknown / historical label unavailable
Defining liabilityGenerally tolerated at therapeutic doses; clinically important risks are agent-specific and increase with interactions or organ impairment.
Mechanism of action: Cycloserine ballicule
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