Adherence to the use of oral forms of antipsychotic therapy, which usually require daily administration, is a major problem when treating patients with schizophrenia. Poor adherence is common and can lead to recurrence of symptoms and hospitalization. Paliperidone palmitate is a long-acting injectable formulation that may simplify the medication regimen for both patients and caregivers. During the APA annual meeting, 3 double-blind, placebo-controlled randomized studies in patients with schizophrenia reported the efficacy and safety of 25, 50, or 100 mg equivalent paliperidone palmitate injected IM every 4 weeks.

Nasrallah HA et al. (NR4=036) noted that at the end of a 92-day trial, all doses of paliperidone significantly improved PANSS total (p<0.001) and CGI-S scores (p<0.01) versus placebo treatment in a patient population that consisted of mostly males who were diagnosed with paranoid schizophrenia.

Kramer M et al. (NR4–072) reported study completion rates of 32% for placebo, 59% for 50 mg, and 61% for 100 mg doses of IM paliperidone in a 36-day trial. More discontinuations due to efficacy and tolerability issues occurred in the placebo treatment group. PANSS total (p=0.001) and 4 factor scores (p<0.01), including positive, negative, anxiety/depression, and disorganized thought, were significantly improved versus placebo at study endpoint.

In a time-to-recurrence study, Hough D et al. (NR4–029) reported that paliperidone 25, 50, 100 mg equivalent administered IM every 4 weeks for 24 weeks significantly (p<0.0001) prolonged time to symptom recurrence versus placebo. Fewer paliperidone-treated patients (10%; 53/156) versus placebo-treated patients (34%; 53/156) experienced symptom recurrence during the study.

The authors reported similar rates and types of adverse events in both placebo and paliperidone treatment groups, except for weight gain, increased prolactin levels, and increased parkinsonism-related EPS events, which occurred more often in the paliperidone-treated patients.

The authors concluded that injectable paliperidone palmitate was an efficacious, safe, and well-tolerated alternative for schizophrenia treatment. A monthly dosing schedule may improve adherence and thus delay symptom recurrence.