A Study of the Impact of Cannabis on Doses of Discharge Antipsychotic Medication in Individuals with Schizophrenia or Schizoaffective Disorder

Abstract

Patients with schizophrenia or schizoaffective disorder have a high prevalence of comorbid cannabis use disorder (CUD). CUD has been associated with poorer outcomes in patients. We compared doses of antipsychotic medications at the time of discharge from hospital among inpatients with schizophrenia or schizoaffective disorder with or without concurrent cannabis use. We reviewed the medical records of patients (N = 8157) with schizophrenia or schizoaffective disorder discharged from the hospital between 2008 and 2012. The patients were divided into two groups; those with urine drug tests positive for cannabis and those negative for cannabis. Doses of antipsychotic medications were converted to chlorpromazine equivalents. Bivariate analyses were done with Student's t test for continuous variables and χ test for categorical variables. Linear regression was carried out to adjust for potential confounders. Unadjusted analysis revealed that the cannabis positive group was discharged on lower doses of antipsychotic medication compared with the cannabis negative group (geometric mean chlorpromazine equivalent doses 431.22 ± 2.20 vs 485.18 ± 2.21; P< 0.001). However, the difference in geometric mean chlorpromazine equivalent doses between the two groups was no longer significant after adjusting for sex, age, race, and length of stay (geometric mean difference 0.99; 95 % CI 0.92-1.10). Though limited by lack of information on duration, amount and severity of cannabis use, as well as inability to control for other non-antipsychotic medications, our study suggests that cannabis use did not significantly impact on doses of antipsychotics required during the periods of acute exacerbation in patients with schizophrenia or schizoaffective disorder.

From Wish to Reality: Soteria in Regular Care—Proof of Effectiveness of the Implementation of Soteria Elements in Acute Psychiatry

“…We were able to exclude additional substance abuse as a moderating factor. Previous studies (28,29) showed a mitigating effect of comorbid substance use in psychotic patients on CPZ dosages. Nevertheless, this effect disappeared when controlling for sociodemographic data and length of stay.…”

“…Therefore, it is conceivable that the effect also loses impact with a certain degree of severity of the disease. It has to be taken into account that previous studies (28,29) included all patients of a hospital, while the present study focuses exclusively on legally accommodated and thus more severely affected patients.…”

“…The discharge medication documented in the discharge letter was used to analyze the CPZ. As CPZ levels can be influenced by comorbid substance use disorder (28,29), we controlled for this and additionally compared both groups, 2 This includes completed suicides and suicide attempts and assaults on employees and fellow patients. In both years, there was neither a completed suicide nor an attempted suicide in the acute psychiatric ward.…”

Psychiatric medication use among pregnant and breastfeeding mothers who used cannabis for mental health concerns: A cross-sectional survey study

“…Though in vivo data on these drug interactions are limited, cannabis smoking cessation is among the implications of two cases of intoxication with CYP1A2 substrates (clozapine and olanzapine). 62 , 63 The subsistence of adverse reactions from cannabis–drug interactions remain unknown, and merit future study.…”