Myser - (Cycloserine 250mg) - Panacea Biotec

DESCRIPTION
For the use of a Registered Medical Practitioner or a Hospital or a Laboratory only.
MYSER
Cycloserine Capsules
Cycloserine, (R)-4-aminoisoxazolidin -3-,one , is a broad spectrum antibiotic that is produced by a
strain of streptomyces orchidaceous. Cycloserine capsule is red/white, size `1' hard gelatin
capsule containing white to pale yellow crystalline powder.
COMPOSITION
Each hard gelatin capsule contains:
Cycloserine IP..................... 250 mg
PHARMACOLOGY
Cycloserine inhibits the cell wall synthesis in susceptible strains of gram-positive and gramnegative
bacteria and in Mycobacterium tuberculosis. Cycloserine, a structural analogue of Dalanine,
antagonizes D-alanine's role in bacterial cell wall synthesis.
PHARMACOKINETICS 1
Absorption/Distribution - When given orally, cycloserine is rapidly absorbed, reaching peak
plasma concentrations in 3 to 8 hours. It is widely distributed throughout body fluids and tissues;
cerebrospinal fluid levels are similar to plasma.
Metabolism / excretion - Approximately 65% of a single dose of cycloserine can be recovered in
urine with in 72 hours after oral administration. The remaining 35% is apparently metabolized to
unknown substances. Renal insufficiency will lead to toxic accumulation it may be removed by
dialysis.
INDICATIONS
For the treatment of active pulmonary and extrapulmonary tuberculosis (including renal diseases
) when organisms are susceptible, after failure of adequate treatment with the primary
medications. Administer in conjuction with other effective chemotherapy.

May be effective in the treatment of acute urinary tract infections 1 caused by susceptible strains
of gram-positive and gram-negative bacteria, especially Enterobacter sp. and Escherichia coli.
CONTRAINDICATIONS 2
Hypersensitivity to cycloserine, epilepsy, depression, severe anxiety, or psychosis, severe renal
insufficiency, excessive concurrent use of alcohol.
WARNINGS
CNS toxicity : Discontinue the drug or reduce dosage if patient develops allergic dermatitis or
symptoms of CNS toxicity, such as convulsions, psychosis, somnolence, depression, confusion,
hyperreflexia, headache, tremor, vertigo, paresis or dysarthria. The risk of convulsions is
increased in chronic alcoholics.
Renal function impairment : Patients will accumulate cycloserine and may develop toxicity if the
dosage regimen is not modified. Patients with severe impairment should not receive the drug.
Monitor patients by hematologic, renal excretion, blood level and liver function studies.
Usage in pregnancy : It is not known whether this drug can cause fetal harm when administered
to a pregnant women or can affect reproduction capacity. Use only if clearly needed.
Usage in lactation : Because of the potential for serious adverse reactions in nursing infants,
decide whether to discontinue nursing or to discontinue the drug, taking into account the
importance of drug to the mother.
Usage in children : Safety and dosage not established for pediatric use.
PRECAUTIONS
Determine blood levels weekly for patients having reduced renal function, for individuals receiving
>500 mg/day, and for those with symptoms of toxicity. Adjust dosage to maintain blood level 500 mg/day for such
symptoms. Pyridoxine may prevent CNS toxicity, but its efficacy has not been proven.
Anemia :Administration has been associated in a few cases with vitamin B12 or folic acid
deficiency, megaloblastic anemia and sideroblastic anemia. If evidence of anemia develops,
institute appropriate therapy.
DRUG INTERACTION
Concurrent administration of ethionamide and cycloserine has been reported to potentiate
neurotoxic side effects. Alcohol and cycloserine are incompatible; alcohol increases the possibility
and risk of epileptic episodes. Concurrent administration of isoniazid may result in increased

incidence of CNS effects especially dizziness.
ADVERSE EFFECTS
CNS toxicity (related to dosages >500 mg/day): Convulsions, drowsiness and somnolence,
headache, tremor, dysarthria, vertigo, confusion and disorientation with loss of memory,
psychosis, possibly with suicidal tendencies, character changes, hyper irritability, aggression,
paresis, hyperreflexia, paresthesias, major and minor (localized) clonic seizures, coma.
CVS : Sudden development of congestive heart failure may occur.
Allergy (not related to dosage) may include skin rash.
Miscellaneous: Elevated transaminase, especially in patients with liver disease.
OVER DOSAGE
Acute toxicity can occur if >1gm is ingested; chronic toxicity is dose related and can occur if >500
mg/day is administered. Toxic effects may include CNS depression with accompanying
drowsiness, headache, vertigo, mental confusion, psychosis, hyperirritability, paresthesias and
dysarthrias. Paresis, convulsions and coma may occur after large doses. Management includes
supportive therapy. Charcoal may be more effective than emesis or lavage, consider charcoal
instead of or in addition to gastric emptying. Hemodialysis removes the drug from the
bloodstream, reserve for patients with life-threatening toxicity. Pyridoxine 200 to 300 mg/day may
treat the neurotoxic effects.
DOSAGE AND ADMINISTRATION
Administer 500 mg to 1 gm daily in divided doses monitored by blood levels. The usual adult
dosage is 250 - 500 mg 3 twice daily at 12 hrs intervals for the first two weeks. Do not exceed 1 g
/day. Pyridoxine 200 to 300 mg/day may prevent the neurotoxic effects.
Children : A dose of 10 to 20 mg/kg/day (max. 0.75 to 1 g) has been recommended.
STORAGE INSTRUCTIONS
Store at a temperature not exceeding 25 o C and protected from moisture.
REFERENCES
1. Antituberculous Drugs, cited in,
Drugs Facts and Comparisons 1995;49 th Ed. :2136-2137.
2. American Medical Association.
Drug Evaluation, 1993; 1607.

3. Mandell GL and Petri WA.
Antimicrobial agents cited in Goodman & Gillman's. The pharmacological basis of
therapeutics, 1996; 9 th ed.: 1155 - 1174.