Acetazolamide for Treatment Resistant Schizophrenia

This is a double blind adjunctive randomized controlled trial for schizophrenia using acetazolamide.

Inclusion Criteria: * Written informed consent. * Both genders, ages 18-55 years (older patients may not tolerate high ACZ dose). * PANSS total score \> 60 and Score \> 4 on one or more items of the 'positive' syndrome items (P1-P7), following treatment at therapeutic doses for 6 weeks with different APDs on 2 occasions. * Stable dose of antipsychotic drug (APD) for \> 1 month, continued throughout the study. * Not participating in another randomized controlled clinical trial (RCT). Exclusion Criteria: * Substance abuse in the past month/dependence past 6 months with the exception of methadone prescribed for opiate withdrawal. * History or current medical/neurological illnesses that may lead to unstable course, e.g., epilepsy. * Pregnancy. * Acetazolamide (ACZ) contraindications: hypersensitivity to ACZ; history of renal hyperchloremic acidosis; Addison's disease/adrenal failure; chronic closed angle-closure glaucoma. * Current or prior treatment with ACZ or history of hypersensitivity to ACZ. * Intellectual disability as defined in DSM 5.