# Comparison of Side Effects Between 3‐Monthly and 1‐Monthly Paliperidone Palmitate Formulations in Patients With Schizophrenia

## TL;DR

This study compares side effects of two paliperidone palmitate formulations in schizophrenia patients, finding no significant increase in side effects when switching to the 3-month formulation.

## Contribution

The study provides real-world evidence on side effect profiles of PP1M versus PP3M in schizophrenia patients.

## Key findings

- UKU side-effect profiles remained similar after switching to PP3M with no increase in total UKU score.
- Common side effects included increased fatigability, hypokinesia, weight gain, and diminished sexual desire.
- Constipation frequency decreased significantly after switching to PP3M.

## Abstract

The paliperidone palmitate 3‐month (PP3M) formulation offers an extended dosing interval compared to the 1‐month (PP1M) formulation. However, data on the comparative side effect profiles of PP1M versus PP3M in real‐world settings remain limited. This study aimed to compare the side effect profiles in patients with schizophrenia receiving PP1M and those who switched from PP1M to PP3M.

Of 473 patients with schizophrenia screened, 132 received long‐acting injectable antipsychotics; 67 initiated PP1M, of whom 43 subsequently converted to PP3M and had evaluable data at both time points. The primary analysis used a within‐patient mirror‐image design (PP1M month‐4 vs PP3M month‐4). Side effects were assessed using the UKU Side Effect Rating Scale, and symptom severity was evaluated with the Scale for the Assessment of Negative Symptoms and the Scale for the Assessment of Positive Symptoms, at 4 months after PP1M initiation and 4 months after PP3M switch.

UKU side‐effect profiles were broadly similar after conversion to PP3M, with no increase in the UKU total score. The most frequent side effects for both formulations were increased fatigability, hypokinesia, weight gain, and diminished sexual desire. The frequency of side effects remained mostly stable, with constipation showing a significant decrease after switching. Side effects were more prevalent in patients with schizophrenia using multiple antipsychotics compared to monotherapy.

In this within‐patient cohort stabilized on PP1M, conversion to PP3M was not associated with an increase in overall UKU side‐effect burden. Selecting the appropriate dose before switching and preferring monotherapy may enhance treatment comfort. These results may help guide clinicians in selecting long‐acting injectable antipsychotics in practice.