Pfizer Inc. has presented a new data at the 165th Annual Meeting of the American Psychiatric Association (APA) in Philadelphia on Pristiq (desvenlafaxine) extended release tablets 50 mg/day for the treatment of major depressive disorder (MDD) in adults, including a long-term relapse prevention study.

These new data, and data from a study in peri- and post-menopausal women with MDD, add to the existing efficacy and safety profile of Pristiq for the treatment of MDD. Lastly, new data also provide information regarding the discontinuation of Pristiq 50 mg/day for the treatment of adults with MDD.

Pfizer has continued to research and evaluate Pristiq, a selective serotonin and norepinephrine reuptake inhibitor (SNRI), since it was approved by the US Food and Drug Administration (FDA) in 2008 for the treatment of MDD in adults. These new Pristiq 50 mg/day data focus on key factors – efficacy, safety, long-term use and discontinuation – that clinicians often consider when assessing antidepressants for the treatment of MDD.

“Patients benefit when their healthcare providers have a variety of medicines from which to choose for complex medical conditions, such as major depressive disorder,” said Christine Guico-Pabia, M.D., MBA, M.P.H., senior director, Global Medical Affairs at Pfizer. “Millions of patients continue to seek relief from their depression and may look to different treatment options. With an established efficacy and safety profile, and new data that provide clinicians with valuable treatment insights, there is a robust body of evidence that supports the use of Pristiq for adult patients with major depressive disorder.”

According to a long-term relapse prevention study, adult MDD patients receiving Pristiq 50 mg/day experienced statistically significant longer time to relapse over six months compared with patients receiving placebo. In the trial, 548 adult patients — who had responded to eight weeks of open-label treatment with Pristiq 50 mg/day and subsequently remained stable for 12 weeks on treatment — were assigned randomly in a double-blind manner to either remain on active treatment or switch to placebo for up to six months of observation for relapse. The primary efficacy endpoint of the study was the time to relapse following randomization to the double-blind phase compared between the two groups.

“These data are important because, as a psychiatrist, my goal is to help patients find a treatment that not only improves their depressive symptoms acutely but also maintains that effect over the longer term. Research like this can help patients to understand why they need to stay on their medications for a longer period of time and not just stop their antidepressant as soon as they feel better,” said Joshua Rosenthal, M.D., board certified adult psychiatrist in Columbia, Maryland, and lead investigator of the Efficacy and Safety of Desvenlafaxine 50 mg/day for Prevention of Relapse in Adult Outpatients Treated for Major Depressive Disorder study. “There is a solid foundation of clinical information about Pristiq, and I am pleased that it is an option for appropriate patients."

The data show that the probability of relapse with Pristiq 50 mg/day was 14.3 per cent versus 30.2 percent with placebo at month six. These long-term results add to existing Pristiq relapse prevention data in the dose range of 200 – 400 mg/day, which were presented at the 160th APA Annual Meeting in 2007.

Pristiq 50 mg/day demonstrated no significant mean weight change as compared to placebo at month six. In the initial open-label phase (eight weeks), the rate of treatment-emergent adverse events (TEAEs) was similar to those observed in prior short-term studies for Pristiq 50 mg/day. There were few TEAEs reported during the stability phase (12 weeks) of the study, with headache being the only TEAE reported in =5 percent of patients. During the double-blind period (six months), the proportion of subjects who experienced at least one TEAE was comparable between groups (54.8 per cent Pristiq-treated; 57.2 per cent placebo). The most common TEAEs in both groups were headache, dizziness and depression, with dizziness and depression occurring in approximately twice as many in the placebo group. A larger percentage of patients on placebo in the double-blind phase (8.3 per cent) discontinued treatment due to adverse events compared with patients who continued on Pristiq 50 mg/day (3.3 per cent). Pristiq 50 mg/day was generally well tolerated over six months of treatment. Interpretation of these findings should take into consideration that only those patients who responded to and demonstrated a level of tolerability for Pristiq 50 mg/day in the open-label phase entered the double-blind phase of the study.

According to an eight-week, multicenter, double-blind, placebo-controlled study, peri- and post-menopausal women with MDD taking Pristiq 50 mg/day achieved statistically significant reductions in the 17-item Hamilton Rating Scale for Depression (HAM-D17) total scores compared to those taking placebo (–9.9, –8.1; P=0.004). The primary efficacy endpoint was the change from baseline in HAM-D17 total score at week eight.4 The HAM-D17 is a validated assessment tool that clinicians often use to rate the severity of a patient's major depressive symptoms. The risk of MDD in a woman’s lifetime is significantly greater than that of a man’s and also is particularly prevalent for women going through the menopausal transition.

The trial evaluated the efficacy and safety of Pristiq 50 mg/day in peri- and post-menopausal women with a primary diagnosis of MDD, aged 40 – 70 years old (n=434). Treatment-emergent adverse events (TEAEs) were reported by 71 percent of Pristiq-treated patients and 68 per cent of patients in the placebo group. The most common TEAEs reported by both groups (=5 per cent in either treatment group) were: headache, nausea, upper respiratory tract infection, constipation, nasopharyngitis (sore throat), dry mouth, dizziness and diarrhoea. In all, 5.5 percent of Pristiq-treated patients discontinued the study due to adverse events (AEs) compared with 2.3 per cent of those receiving placebo.

This study demonstrated that abrupt discontinuation of treatment with Pristiq 50 mg/day resulted in no statistically significant difference in Discontinuation-Emergent Signs and Symptoms Scale (DESS) total scores compared to a one-week taper using 25 mg/day, the primary endpoint of this study. Abrupt discontinuation of Pristiq 50 mg/day was associated with a numerically greater number of new-onset adverse events (AEs) in the double-blind phase compared with the one-week taper using 25 mg/day. Pristiq is available in 50 mg and 100 mg extended release tablets.