Gabapentin decreases PHN

Gabapentin treatment helped more than half of patients achieve relief from postherpetic neuralgia pain (PHN) in a “real-world clinical practice,” researchers said here.

In an open-label study, 51.1% of patients with PHN, also known as after-shingles pain, reported they were “very much improved” or “much improved,” using the Patient Global Impression of Change scale, after 8 weeks of therapy with once-daily gabapentin, reported Amanda McFann, MSN, of Pain Specialists of Charleston, S.C., and colleagues at the American Academy of Pain Medicine meeting.

Once-daily gabapentin for PHN is a tablet that swells in gastric juices and slowly releases the active agent.

For this multicenter, phase IV study, McFann’s group had no exclusion criteria beyond those in the product label in order to reflect a real-world clinical setting. They enrolled 75 men and 122 women diagnosed with PHN.

The patients were about 67-years-old, which is a common age for inclusion in a PHN study, McFann said. More than 80% were Caucasian. They had experienced postherpetic neuralgia for an average of 29 months.

Eligible patients were titrated to a dosage of 1,800 mg of gabapentin over 2 weeks, for total treatment of 8 weeks.

Efficacy was assessed using a visual analog scale (VAS) and the Brief Pain Inventory (BPI).

The mean percent change in VAS score from baseline was -26.5% at week two and -30.6% at week eight.

The proportion of responders in VAS (≥30% reduction from baseline) was 45.8% in week two and 53.2% in week eight. Patients with ≥50% reduction in VAS score from baseline were 40.5% in week two and 33.2% in week eight.

BPI were all significantly reduced by week eight, with scores dropping two points for the worst pain; one point for least pain, and 1.5 points for average pain. Scores for all BPI subcategories, including general activity, mood, walking ability, sleep interference, and enjoyment of life significantly favored treatment with gabapentin, McFann said.

In terms of adverse events, 18.8% of patients experienced treatment-emergent adverse events that led to study discontinuation. In addition, 2.5% of patients experienced serious treatment-emergent adverse events, although none were found to be related to gabapentin, the investigators reported. No patients died during the study period.

The most common adverse events were dizziness (13.7%), somnolence (5.6%), nausea (3.6%), and headache (3.6%).

“Most of the adverse events seen with the treatment occurred in the titration period,” McFann explained.

Disclosure

The study was sponsored by Depomed, the makers of Gralise.

McFann and Sloan reported no conflicts of interest.

Reference:
Dunteman E, et al Safety and efficacy of gastroretentive gabapentin in real-world clinical practice for treatment of patients with postherpetic neuralgia AAPM 2013; Abstract 121.