SAN ANTONIO, TX—Urine drug monitoring may help identify medication nonadherence and/or substance misuse, allowing early clinical intervention and improved therapeutic outcomes, Mancia Ko, PharmD, MBA, from Ingenuity Health, Baltimore, MD, reported at the U.S. Psychiatric & Mental Health Congress. 

For patients with severe mental illness, management through antipsychotic drugs is essential to prevent relapse. As many as one-half of patients with mental illness have shown non-adherence to to their prescription regimen, explained Dr. Ko. In schizophrenia, medication nonadherence is linked to negative clinical outcomes such as symptom recurrence, higher inpatient admissions, and longer hospital stay. In bipolar disorder, nonadherence is associated with greater mood symptoms and worse functioning. These patients also have a higher risk of various substance use disorders and any current substance use may further increase the risk for treatment adherence.

In the retrospective analysis, Dr. Ko and coauthor Thomas Smith, MD aimed to evaluate the incidence of potential nonadherence for patients prescribed antipsychotics and to identify the use of illicit substances and/or non-prescribed drugs in these patients through urine drug monitoring. 

A total of 62,342 urine samples were collected from patients prescribed antipsychotics between 2013–2016; study patients were 49.2% male. Urine samples were labeled as antipsychotic drug positive or antipsychotic drug negative. Also, they were labeled as positive or negative for non-prescribed opiate, synthetic opioids or benzodiazepines, cocaine, and THC.

The medications and related metabolites tested were as follows: aripiprazole, clozapine, haloperidol, lurasidone, olanzapine, paliperidone, quetiapine, risperidone, and ziprasidone. 

The data indicated the urine drug monitoring was positive for antipsychotic drugs in 75.3% of samples and negative in 24.7% of samples, which differed greatly by prescribed drug. Further, a non-prescribed antipsychotic (either parent or metabolite) was detected in 6.7% of samples where 4.8% had both prescribed and non-prescribed antipsychotics and 1.9% were missing the prescribed antipsychotic drug. 

Quetiapine (32.3%), ziprasidone (31.0%), or multiple antipsychotic drugs (35.8%) were associated with the highest rate of negative samples. Aripiprazole (25.9%), risperidone (17.2%), olanzapine (13.3%), and haloperidol (23.4%) were mid-range, and urine samples from paliperidone (7.5%) and clozapine (3.4%) were least commonly negative. 

“Patients ages <40 had the highest rate of negative test results, which steadily declined with every decade of life thereafter compared to ages 30–39,” noted Drs. Ko and Smith. The adjusted odds ratio (aOR) was 0.88 (95% CI: 0.84–0.93) for 40–49 years; aOR 0.75 (95% CI: 0.71–0.79) for 50–59 years; aOR 0.69 (95% CI: 0.63–0.75) for 60–69 years; and aOR 0.61 (95% CI: 0.49–0.75) for >70 years. 

A non-synthetic opiate/synthetic opioid was more likely to be found in antipsychotic drug negative individuals than positive individuals (14.5% vs. 11.2%, OR 1.34, 95% CI: 1.27–1.42), as well as a non-prescribed benzodiazepine (7.3% vs. 5.7%, OR 1.29, 95% CI: 1.20–1.39). 

Moreover, THC (20.7% vs. 17.1%, OR 1.26, 95% CI: 1.20–1.32) or cocaine (5.7% vs. 3.5%, OR 1.67, 95% CI: 1.54–1.83) was more likely to be found in antipsychotic drug negative individuals than antipsychotic drug positive patients, the authors added. 

Potential nonadherence to prescribed antipsychotics was associated with higher use of marijuana, cocaine, and non-prescribed opioids and benzodiazepines. “Urine drug monitoring in patients who are prescribed antipsychotic drugs can be of value in both monitoring adherence to antipsychotic drug therapy, and in identifying the use of inappropriate prescription and non-prescription substances,” concluded Drs. Ko and Smith. The single most important modifiable factor contributing to relapse and hospitalization in patients with mental illness may be nonadherence, they added.