Evaluation of Prescribing Patterns of Long-Acting Injectable Antipsychotics Within a Community Health System

Use and Discontinuation Rates of Long-Acting Injectable Antipsychotics Between Race/Ethnicity in Older Adults Using Medicaid Databases

OBJECTIVE

The primary objective of this study was to assess the prescribing patterns of long acting injectable (LAI) antipsychotics in an older adult population. Secondary objectives were to determine if there were differences in treatment discontinuation rates between different LAI agents and race/ethnicity.

METHODS

Merative MarketScan Multi-State Medicaid Databases (2017-2021) were used to identify patients 65 years or older who were prescribed a LAI antipsychotic. Pharmacy claims for LAI antipsychotics were referenced via National Drug Code (NDC) by brand/generic name and dose. International Classification of Diseases, 10th edition (ICD-10) codes were used to identify older adults diagnosed with schizophrenia, schizotypal or schizoaffective disorders. Those with dementia or related disorders were censored. Conditional associations between race/ethnicity and generation of LAI antipsychotics were investigated using logistic regression controlling for age, sex, and health plan. Cox proportional hazard regression was used to compare the distribution of time until treatment discontinuation among older adults across LAI antipsychotics.

RESULTS

A total of 526 older adults (59% female) with an average age of 70.4 ± 5.5 years met inclusion for analysis. The most commonly used LAI antipsychotics included paliperidone palmitate-1 month formulation (~35%), haloperidol decanoate (~24%), and risperidone microspheres (~15%). Overall, approximately 32% received LAI first-generation antipsychotics and 68% received LAI second generation antipsychotics. Blacks (n = 204) received LAI first-generation antipsychotics more often than Whites (n = 283); (OR: 1.74, 95% [1.18, 2.56], p < 0.01). When controlling for age, sex, and race/ethnicity, LAI first-generation antipsychotics showed earlier discontinuation rates compared to LAI second-generation antipsychotics (HR: 2.12, 95% CI [1.45, 3.10], p < 0.001).

CONCLUSIONS

LAI first-generation antipsychotics showed treatment discontinuation significantly earlier compared to LAI second-generation antipsychotics. Furthermore, Blacks were prescribed LAI first-generation antipsychotics at a higher rate than Whites, which may contribute to poorer health outcomes. Futures studies are needed to establish a causal relationship.

Prescribing patterns of long-acting injectable antipsychotics in a community setting in South Africa

Background

Long-acting injectable antipsychotics (LAI - APs) improve adherence to antipsychotics and decrease functional decline in schizophrenia. Yet they are prescribed late, in patients with established functional decline. Although LAI - APs are widely prescribed in South Africa, there is a paucity of research regarding the prescription profile for LAI - APs.

Aim

This study aimed to describe prescribing practices for LAI - APs at psychiatric clinics.

Setting

Community psychiatric clinics in South Africa.

Methods

A retrospective review of the psychiatric files of all patients on LAI - APs attending the clinics over the study period was conducted. Sociodemographic, clinical and pharmacological information regarding the LAI - AP prescribed was extracted from the files.

Results

A total of 206 charts were examined. The mean age of the study population was 46 (SD ± 12) years. Significantly more patients were male (n = 154; 74.8%), single (n = 184, 89.3%) and unemployed (n = 115; 55.8%) (p < 0.001). Approximately half had a comorbid substance use disorder (47.6%). The most common indication for the prescription of a LAI - AP was non-adherence (66%). Only 9.7% of the patients were prescribed a LAI - AP alone. No significant socio-demographic or clinical characteristic was associated with this prescribing habit. A LAI - AP was prescribed in combination with an oral antipsychotic, mood stabiliser or antidepressant in 53.9%, 44.7% and 7.8% of patients, respectively.

Conclusion

Long-acting injectable antipsychotics were prescribed mainly following noncompliance with oral antipsychotics and may represent a missed opportunity to prevent functional decline. The high prevalence of LAI - AP polypharmacy has been highlighted.

Pharmacokinetic Correlates of Once-Monthly Paliperidone Palmitate-Related Adverse Drug Reactions

OBJECTIVE

The objective of this study was to investigate associations between pharmacokinetic correlates and once-monthly paliperidone palmitate (PP1M)-related adverse drug reactions (ADRs).

METHODS

Plasma concentrations and dose-adjusted plasma concentrations ('concentration-by-dose' [C/D]) of paliperidone from a naturalistic therapeutic drug monitoring database of PP1M-treated patients were compared between patients with ADRs, classified according to the Udvalg for Kliniske Undersogelser side-effect rating scales categories, and patients without ADRs. Analyses included non-parametric tests and a logistic regression model with a significance level set at 0.05.

RESULTS

In 172 patients, we found no differences in sex, age, smoking, body mass index, PP1M dose, paliperidone plasma concentrations, and C/D values (p > 0.05) between 44 patients with and 128 patients without PP1M-related ADRs. We did not detect differences when specifying for different types of ADRs (p > 0.05). Injection intervals were shorter in patients with vs patients without ADRs (p = 0.03). The logistic regression did not report effects for sex, plasma concentrations, or C/D values (p > 0.05). Post hoc analyses in male patients receiving PP1M every 28 weeks reported higher paliperidone concentrations and C/D values in patients with vs without ADRs (p = 0.049 and p = 0.022). Within the group of male patients, we found an odds ratio of 3.07 for PP1M-associated ADRs in patients with C/D values above 7.7 (ng/mL)/(mg/day).

CONCLUSIONS

Our findings did not reveal distinct patterns of paliperidone concentrations in patients with PP1M-related ADRs. However, male patients receiving PP1M every 28 days with C/D values higher than 7.7 (ng/mL)/(mg/day) showed a higher risk for ADRs, implying that therapeutic drug monitoring may be useful in assessing the risk of PP1M-related ADRs.