This article is more than 5 years old. Information may no longer be current.

Age may modify the effects of long-acting injectable antipsychotics

Researchers found that long-acting injectable haloperidol decanoate was linked to lower rates of efficacy failure compared with long-acting injectable paliperidone palmitate, but only among younger individuals with schizophrenia.

In a previous randomized controlled trial with 2-year follow-up, known as A Comparison of Long-Acting Injectable Medications for Schizophrenia, researchers compared haloperidol with paliperidone in 311 people with schizophrenia at risk for relapse due to nonadherence or substance abuse, and found no difference in rates of efficacy failure.

Using data from this study, T. Scott Stroup, MD, MPH, from the department of psychiatry at Columbia University and New York State Psychiatric Institute, and colleagues examined whether treatment effects on efficacy failure in people who received haloperidol or paliperidone differed by age, sex, race, substance abuse, baseline symptom severity and baseline adherence. They also assessed this modified safety outcomes. Efficacy failure was defined as:

• psychiatric hospitalization;
• crisis stabilization;
• more outpatient visits;
• inability to discontinue oral antipsychotic;
• discontinued assigned long-acting injectable because of poor therapeutic benefit; or
• ongoing or repeated need for add-on oral antipsychotic.

Stroup and colleagues found a significant interaction between age and treatment on efficacy failure (P = .009), but not between treatment and any other subgroup tested. Analysis revealed that younger participants aged 18 to 45 years receiving haloperidol had longer time to efficacy failure than those receiving paliperidone (P = .029). Among older participants aged 45 to 65 years receiving paliperidone, the researchers observed a trend for longer time to efficacy failure (P = .196) Other treatment outcomes, including akathisia and increases in serum prolactin levels, were also modified by age, according to the results.

“Further efforts to examine heterogeneity of treatment response of antipsychotic medication by age are needed,” Stroup and colleagues wrote. “If differential effects of medication by age are confirmed, this may lead to improved selection of treatment, shorter time to treatment response and better outcomes.” – by Savannah Demko

Disclosure: Stroup reports a grant from Auspex Pharmaceuticals. Please see the study for all other authors’ relevant financial disclosures.