Minocycline add-on to risperidone for treatment of negative symptoms in patients with stable schizophrenia: Randomized double-blind placebo-controlled study

The objective of this study was to assess the efficacy and tolerability of minocycline add-on to risperidone in treatment of negative symptoms of patients with chronic schizophrenia. In a randomized double-blind placebo-controlled study, 40 patients with chronic schizophrenia who were stabilized on risperidone for a minimum duration of eight weeks were recruited. The patients were randomly assigned to minocycline (titrated up to 200 mg/day) or placebo in addition to risperidone (maximum dose of 6 mg/day) for eight weeks. Positive and Negative Syndrome Scale (PANSS), Hamilton Depression Rating Scale, and Extrapyramidal Syndrome Rating Scale were used. Thirty-eight patients completed the study. Significant time×treatment interaction for negative [F(2.254,85.638)=59.046, P<0.001] general psychopathology [F(1.703,64.700)=6.819, P=0.001], and positive subscales [F(1.655,62.878)=5.193, P=0.012] as well as total PANSS scores [F(1.677,63.720)=28.420, P<0.001] were observed. The strongest predictors for change in negative symptoms were the treatment group (β=−0.94, t=−10.59, P<0.001) followed by the change in PANSS positive subscale (β=−0.185, t=−2.075, P=0.045). Side effect profiles of the two treatment regimens were not significantly different. Minocycline seems to be an efficacious and tolerable short-term add-on to risperidone for treatment of negative and general psychopathology symptoms of schizophrenia.