Overview
DESCRIPTION D -Cycloserine, (R)-4-amino-3-isoxazolidinone, is a broad-spectrum antibiotic that is produced by a strain of Streptomyces orchidaceus and has also been synthesized. Cycloserine is a white to off-white powder that is soluble in water and stable in alkaline solution. It is rapidly destroyed at a neutral or acid pH. Cycloserine has a pH between 5.5 and 6.
Mechanism of Action
CLINICAL PHARMACOLOGY 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 mcg/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, file, sputum, amniotic fluid, and lung and lymph tissues. Approximately 65% of a single dose of cycloserine can be recovered in the urine within 72 hours after oral administration. The remaining 35% is apparently metabolized to unknown substances.
Indications
- INDICATIONS AND USAGE Cycloserine is indicated in the treatment of active pulmonary and extrapulmonary tuberculosis (including renal disease) when the causative organisms are susceptible to this drug and when treatment with the primary medications (streptomycin, isoniazid, rifampin, and ethambutol) has proved inadequate. Like all antituberculosis drugs, cycloserine should be administered in conjunction with other effective chemotherapy and not as the sole therapeutic agent.
Common Doses
- 500 mg
- 1 g
- 250 mg
Dosage
DOSAGE AND ADMINISTRATION 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. 1 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.
Contraindications
- CONTRAINDICATIONS Administration is contraindicated in patients with any of the following: • Hypersensitivity to cycloserine • Epilepsy • Depression, severe anxiety, or psychosis • Severe renal insufficiency • Excessive concurrent use of alcoho
Side Effects
- ADVERSE REACTIONS Most adverse reactions occurring during therapy with cycloserine involve the nervous system or are manifestations of drug hypersensitivity. The following side effects have been observed in patients receiving cycloserine: Nervous system symptoms (which appear to be related to higher dosages of the drug, i.e., more than 500 mg daily) • Convulsions • Drowsiness and somnolence • Headache • Tremor • Dysarthria • Vertigo • Confusion and disorientation with loss of memory • Psychoses, possibly with suicidal tendencies • Character changes • Hyperirritability • Aggression • Paresis •...
Interactions
- No major interactions listed on the FDA label. Always consult a healthcare professional.