Guidelines for Using Cycloserine (Mybertiq)
Cycloserine should be used cautiously with careful monitoring for neuropsychiatric side effects, at doses not exceeding 500 mg daily, with pyridoxine supplementation to minimize toxicity. 1
Dosing Recommendations
Adults: 10-15 mg/kg per day (maximum 1000 mg), typically 500 mg daily
- Start with lower doses and titrate slowly to minimize side effects
- Doses above 500 mg/day significantly increase toxicity risk
- Serum concentration monitoring recommended (target: 20-35 mg/ml) 1
Children: 10-15 mg/kg per day (maximum 1000 mg/day)
Administration
- Available as 250 mg capsules
- Can be given as a single daily dose or divided into two doses
- Consider bedtime dosing to minimize neuropsychiatric effects
Required Monitoring
Baseline assessment:
- Neuropsychiatric status
- Renal function
- Seizure risk assessment
- If taking phenytoin: baseline serum phenytoin levels
Ongoing monitoring:
- Monthly neuropsychiatric assessment (more frequently if symptoms develop)
- Serum drug concentration measurements until appropriate dose established
- Monitor phenytoin levels in patients taking this medication 1
Special Populations
Renal Impairment
- Contraindicated in patients with creatinine clearance <50 ml/minute unless receiving hemodialysis
- Hemodialysis patients: 500 mg three times weekly or 250 mg daily
- Serum drug concentration monitoring essential 1
Hepatic Disease
- No specific dose adjustments needed except in alcohol-related hepatitis
- Caution: Increased seizure risk in patients with alcohol-related hepatitis 2
Pregnancy
- Use only when no suitable alternatives exist
- Limited safety data in pregnancy 1
Side Effects Management
Neuropsychiatric Effects (Most Common)
- Seizures (16% with 500 mg twice daily; 3% with 500 mg once daily)
- Psychosis, anxiety, depression, confusion
- Headaches, tremor, vertigo, dysarthria
- Prevention: Administer pyridoxine 100-200 mg/day 1
- Management: Dose reduction or discontinuation for severe symptoms
Other Side Effects
- Peripheral neuritis (rare)
- Allergic dermatitis
- Gastrointestinal disturbances (nausea, vomiting)
Drug Interactions
- May exacerbate underlying seizure disorders
- Monitor phenytoin levels in patients taking both medications
- Alcohol consumption increases seizure risk
Patient Education
- Report any neuropsychiatric symptoms immediately
- Avoid alcohol consumption
- Take with pyridoxine as prescribed
- Importance of adherence to monitoring schedule
Pitfalls and Caveats
- Neuropsychiatric side effects can be severe and may require immediate dose adjustment
- Never exceed 500 mg daily without careful monitoring
- Always co-administer with pyridoxine to reduce neurotoxicity
- Patients with history of psychiatric disorders or seizures require particularly close monitoring
- Drug accumulation can occur in renal impairment, leading to increased toxicity
Cycloserine penetrates the CSF well, achieving concentrations equivalent to those in serum, making it useful for CNS tuberculosis infections, but its significant neuropsychiatric side effect profile requires careful patient selection and monitoring 2.