Minocycline Augmentation of Clozapine for Treatment Resistant Schizophrenia

Inclusion Criteria: * Male and female patients aged between 18-65 years, IQ \>70 (to complete assessments) identified by treating psychiatrist. * Confirmation of schizophrenia by using The MINI psychiatric interview (at baseline only) * Assessed as competent to provide informed consent by treating psychiatrist. * Antipsychotic medication has remained stable 4 weeks prior to baseline \*. Assessed as a partial responder to clozapine: patients prescribed clozapine at a stable therapeutic dose for a minimum of 3 months with total Positive and Negative Syndrome Schizophrenia (PANSS) score \>70. Exclusion Criteria: * Prior history of intolerance or serious side effects (hepatotoxicity, photosensitivity, blood dyscrasias) to any of the Tetracyclines. * Concomitant Penicillin therapy or concomitant anticoagulant therapy. * Active substance abuse (except nicotine or caffeine) or dependence within the last three months according to ICD 10 criteria. * Treatment with Warfarin or Lamotrigine. * Current or previous treatment with minocycline or other tetracycline antibiotics in the preceding three months before study entry. * Relevant current or past hematologic, hepatic, renal, neurological or other medical disorder that in the opinion of the principal investigator may interfere with the study. * Pregnant or breast-feeding females