Before treatment with cycloserine is initiated, cultures should be taken and the organism’s susceptibility to the drug should be established. In
tuberculous infections, the organism’s susceptibility to the other antituberculosis agents in the regimen should also be demonstrated.
Anticonvulsant drugs or sedatives may be effective in controlling symptoms of CNS toxicity, such as convulsions, anxiety, and tremor. Patients receiving more than 500 mg of cycloserine daily should be closely observed for such symptoms. The value of pyridoxine in preventing CNS toxicity from cycloserine has not been proved.
Administration of cycloserine and other antituberculosis drugs has been associated in a few instances with vitamin B12 and/or
folic–acid deficiency, megaloblastic anemia, and sideroblastic anemia. If evidence of anemia develops during treatment, appropriate studies and therapy should be instituted.
Cycloserine is effective orally and is currently administered only by this route. The usual dosage is 500 mg to 1 g daily in divided doses monitored by blood levels.2 The initial adult dosage most frequently given is 250 mg twice daily at 12–hour intervals for the first 2 weeks. A daily dosage of 1 g should not be exceeded.
Toronto Research Chemicals - TRC Canada
Cycloserine inhibits cell–wall synthesis in susceptible strains of gram–positive and gram–negative bacteria and in Mycobacterium tuberculosis.
Interferes with Cell Wall Synthesis - Mechanism of …
After oral administration, cycloserine is readily absorbed from the gastrointestinal tract, with peak blood levels occurring in 4 to 8 hours.
Blood levels of 25 to 30 μg/mL can generally be maintained with the usual dosage of 250 mg twice a day, although the relationship of plasma levels to dosage is not always consistent. Concentrations in the cerebrospinal fluid, pleural fluid, fetal blood, and mother’s milk approach those found in the serum. Detectable amounts are found in ascitic fluid, bile, sputum, amniotic fluid, and lung and lymph tissues. Approximately 65 percent of a single dose of cycloserine can be recovered in the urine within 72 hours after oral administration. The remaining 35 percent is apparently metabolized to unknown substances. The maximum excretion rate occurs 2 to 6 hours after administration, with 50 percent of the drug eliminated in 12 hours.
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Administration is contraindicated in patients with any of the
Hypersensitivity to cycloserine
Depression, severe anxiety, or psychosis
Severe renal insufficiency
Excessive concurrent use of alcohol
Summary of Antibiotics Dr. Hliebov
Concurrent administration of ethionamide has been reported to potentiate neurotoxic side effects.
Alcohol and cycloserine are incompatible, especially during a regimen calling for large doses of the latter. Alcohol increases the possibility and risk of epileptic episodes.
Concurrent administration of isoniazid may result in increased incidence of CNS effects, such as dizziness or drowsiness. Dosage adjustments may be necessary and patients should be monitored closely for signs of CNS toxicity.
Carcinogenesis, Mutagenicity, and Impairment of Fertility
Studies have not been performed to determine potential for carcinogenicity. The Ames test and unscheduled DNA repair test were negative. A study in 2 generations of rats showed no impairment of fertility relative to controls for the first mating but somewhat lower fertility in the second mating.