Most medications used for schizophrenia are in the phenothiazine family. The atypical antipsychotics are so called because they are chemically quite different. They appear to cause fewer side effects than the phenothiazine drugs
Medications in this family include:
Possible Harmful Interaction
The herb St. John’s wort might reduce levels of these medications in the blood. 1 This could lead to an increase in the severity of psychotic symptoms.
Perhaps even more dangerously, if medication levels are adjusted for an individual already taking St. John’s wort, stopping the herb could cause these levels to rise, potentially causing dangerous toxic symptoms.
Possible Benefits and Risks
A few studies suggest that the amino acid glycine may augment the action of phenothiazine antipsychotic drugs. It might also augment the action of olanzapine and risperidone, but whether it augments or decreases the effectiveness of clozapine remains unclear. 3-7 See the Glycine article for a more detailed discussion of this subject.
Possible Helpful Interaction
Highly preliminary evidence suggests that ginkgo might reduce the side effects and increase the efficacy of various antipsychotic medications, including atypical antipsychotic drugs. 2
1. De Smet PA and Touw DJ. Safety of St. John's wort. Lancet 355:575–576, 2000.
2. Liu P, Luo HC, Shen YC, et al. Combined use of Ginkgo biloba extracts on the efficacy and adverse reactions of various antipsychotics [translated from Chinese]. Chin J Clin Pharmacol. 1997;13:193–198.
3. Heresco-Levy U, Ermilov M, Lichtenberg P, et al. High-dose glycine added to olanzapine and risperidone for the treatment of schizophrenia. BiolPsychiatry . 2004;55:165-71.
4. Potkin SG, Jin Y, Bunney BG, et al. Effect of clozapine and adjunctive high-dose glycine in treatment-resistant schizophrenia. Am J Psychiatry . 1999;156:145–147.
5. Evins AE, Fitzgerald SM, Wine L, et al. Placebo-controlled trial of glycine added to clozapine in schizophrenia. Am J Psychiatry . 2000;157:826-828.
6. Diaz P, Bhaskara S, Dursun SM, et al. Double-blind, placebo-controlled, crossover trial of clozapine plus glycine in refractory schizophrenia negative results. J Clin Psychopharmacol. 2005;25:277-278.
7. Buchanan RW, Javitt DC, Marder SR, et al. The cognitive and negative symptoms in schizophrenia trial (CONSIST): the efficacy of glutamatergic agents for negative symptoms and cognitive impairments. Am J Psychiatry. 2007;164:1593-1602.
Last reviewed August 2011 by EBSCO CAM Review Board
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