What are the common side effects of Corzyna?

Common Side Effects of Cycloserine (Corzyna)

Neuropsychiatric side effects are the most common and concerning adverse reactions associated with cycloserine (Corzyna), including anxiety, depression, psychosis, confusion, headaches, tremor, vertigo, dysarthria, and seizures. 1

Neuropsychiatric Effects

Cycloserine readily crosses the blood-brain barrier, with CSF concentrations approaching those in serum, which explains its significant neuropsychiatric effects 1. These effects range from:

• Mild reactions: Headache, restlessness, confusion, tremor, vertigo, dysarthria
• Severe reactions: Psychosis, depression, anxiety, seizures

Seizures have been reported to occur in up to 16% of patients receiving 500 mg twice daily but in only 3% when receiving 500 mg once daily 2. The drug may exacerbate underlying seizure disorders or mental illness.

Other Common Side Effects

• Peripheral nervous system: Peripheral neuritis (numbness or tingling in extremities) 1
• Gastrointestinal effects: Nausea, vomiting, and other gastrointestinal disturbances 1
• Dermatological: Allergic dermatitis and skin reactions 1

Risk Factors for Increased Side Effects

• Alcohol-related hepatitis: Increased risk of seizures 2, 1
• Renal impairment: Drug can accumulate, increasing risk of toxicity 2
• Higher doses: Toxicity is more common at doses over 500 mg/day 2
• Concomitant medications: Patients taking phenytoin require monitoring due to potential interactions 1

Monitoring and Management

The Centers for Disease Control and Prevention recommends:

1. Regular assessment: Neuropsychiatric status should be assessed at least monthly and more frequently if symptoms develop 1
2. Serum concentration measurements: May be necessary until an appropriate dose is established, aiming for a peak concentration of 20-35 mg/ml 2
3. Pyridoxine supplementation: May help prevent and treat neurotoxic side effects, usually given at 100-200 mg/day 2
4. Dose adjustment: For patients with renal impairment or those experiencing severe side effects 2, 1

Special Considerations

• Pregnancy: Limited data on safety; should only be used when no suitable alternatives exist 2, 1
• Renal disease: Should not be used in patients with creatinine clearance <50 ml/minute unless receiving hemodialysis 2, 1
• Hemodialysis patients: Dose should be 500 mg three times weekly or 250 mg daily 2, 1

Prevention of Side Effects

• Start with lower doses and titrate slowly to minimize neuropsychiatric side effects 1
• Patient education about potential symptoms and importance of reporting them immediately 1
• If severe neuropsychiatric symptoms develop, dose reduction or discontinuation may be necessary 1

Understanding these common side effects and implementing appropriate monitoring can help manage the risks associated with cycloserine therapy while maximizing its therapeutic benefits.