Cycloserine($ (generic but high price))

Antibiotic (50-150 mg: enhances learning as glutamate agonist; Over 500mg: treats depression as glutamate antagonist)

Dosing

Depression 500 mg bid (start 250mg 1 qd and raise by 250mg every 4-7 days). To augment exposure therapy in anxiety disorders, use 50-100mg (1/2 of 250mg) q24 hr take 1-2 hour before exposure (but it’s a capsule so have to use 250mg). To augment TMS, 100 mg 1-2 hours before treatment for first 2 weeks of TMS or iTBS. Give with vitamin B6 200 mg/day to reduce side effects.

Management

Low dose is well tolerated. Higher dose (for depression) can cause ketamine-like effects including mental status change. It is an old antibiotic only used in third world countries now so may need to go to independent pharmacists to special order it.

In low doses improves learning in exposure therapy. In high doses works for treatment resistant depression with glutamatergic effects.

EMR Text