The following article is part of conference coverage from the 2019 American Psychiatric Association Annual Meeting (APA 2019) in San Francisco, CA. Psychiatry Advisor’s staff will be reporting breaking news associated with research conducted by leading experts in psychiatry. Check back for the latest news from APA 2019.

SAN FRANCISCO — Psychiatrists need to take into account possible drug-drug interactions when prescribing third generation antipsychotics to their patients with schizophrenia, as highlighted by a case study presented at the American Psychiatric Association Annual Meeting, held May 18-22, 2019, in San Francisco, California.

This study presented the case of a 29-year-old man diagnosed with schizophrenia who was prescribed, in addition to his normal medication regimen, cariprazine, a partial dopamine agonist with a high affinity for D2 and D3 dopamine receptors. The patient was hospitalized for exhibiting acute psychotic decompensation following the addition of cariprazine to his drug regimen. Earlier in the year, the patient had been hospitalized and had been successfully stabilized with a long-acting paliperidone palmitate injection. It was later found that the patient had been administered cariprazine in the 2 weeks preceding his readmission and had subsequently experienced a decompensation of his clinical state, and experienced auditory hallucinations which prompted him to fast. Clinicians withheld cariprazine, based on the concern that the drug’s affinity for D2 and D3 receptors may inhibit binding of paliperidone palmitate to these receptors. This intervention resulted in the patient’s steady improvement and reduction in psychotic symptoms. Six days after cariprazine was withheld (ie, > than the 2-5 days half-life of cariprazine), the patient improved sufficiently to be discharged.

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”[W]e highlight the importance of awareness towards adverse drug-drug interactions, especially as it relates to binding kinetics,” noted the case study author.

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Khan KS, Agustines DA. When less is more: withholding an antipsychotic leads to improvement in symptoms of schizophrenia. Poster presentation at: American Psychiatric Association Annual Meeting; May 18-22, 2019; San Francisco, CA. Abstract 50.