Safety of Lidocaine Patch 5%

Phoenix—A post hoc analysis of 2 studies found that patients with postherpetic neuralgia tolerated receiving the combination therapy of lidocaine patch 5% and calcium channel a2-d ligands, with most treatment-related adverse events attributed to calcium channel a2-d ligands.

Results were presented during a poster session at the AAPM meeting. The poster was titled Safety of Combination Therapies for Postherpetic Neuralgia.

The authors noted that 70% of people >60 years of age and 34% of patients with acute herpes zoster infection, which is commonly known as shingles, have postherpetic neuralgia, which results from peripheral nerve damage. This condition is typically persistent, and people with postherpetic neuralgia have trouble with daily living.

Lidocaine patch 5% is FDA-approved and recommended for first-line treatment of postherpetic neuralgia, according to United States and world guidelines. The authors mentioned lidocaine patch 5% is also effective and tolerated in combination with gabapentin and pregabalin.

This analysis examined trials of adults who had postherpetic neuralgia and a pain intensity score >4 on a 10-point scale, in which 0 is no pain and 10 is the worst imaginable pain. Both studies began with a monotherapy phase in which patients took lidocaine patch 5% or a calcium channel a2-d ligand.

If patients in the first study had pain intensity >4 on question 5 of the Brief Pain Inventory during the last 24 hours of treatment, they then used lidocaine patch 5%  in combination with gabapentin ≤4 times per day for 2 weeks. In the second study, patients who had pain intensity >4 on the Numeric Rating Scale on average during the 3 days of treatment entered a phase in which they used lidocaine patch 5% plus pregabalin ≤3 times per day for 8 weeks.

The mean age in the first study was 70.3 years, and 4 of the 11 patients (36.4%) were men. In the second study, the mean age was 65.8 years, and 20 of 35 patients (57.1%) were men.

Lidocaine patch 5% plus gabapentin was associated with a reduction in pain intensity after 2 weeks, while lidocaine patch 5% in combination with pregabalin was associated with a reduction in pain intensity after 8 weeks. In each group, 1 patient did not experience change in pain and 1 patient said pain was worse after receiving the combination therapy.

In the first study, 4 patients had a treatment-emergent adverse event, while 1 patient discontinued use because of an adverse event. None of the patients had >1 adverse event. In the other trial, there were 18 treatment-emergent adverse events in 11 patients. Of the 18 events, 10 were mild, 4 were moderate, and 4 were severe, but none were deemed as serious, according to the authors.

Meanwhile, 1 patient who used lidocaine patch 5% plus gabapentin and 6 patients in the lidocaine patch 5% plus pregabalin group had treatment-related adverse events. The person in the first study had an ecchymosis of moderate intensity, which the authors said was likely related to lidocaine patch 5%. Four patients, including 3 in the second study, discontinued the trial due to a treatment-related adverse event.

This poster was supported by Endo Pharmaceuticals Inc.