Clinical Trial One
Topical lidocaine relieves postherpetic neuralgia (PHN) more effectively than a
vehicle topical patch: results of an enriched enrollment study
Patients Preferred LIDODERM vs placebo patch (78% vs 9%)
Authors
Bradley S. Galer, MD, Michael C. Rowbotham, MD, Jill Perander,
and Erika Friedman.
Abstract
This study compared the efficacy of topical lidocaine patches versus
vehicle (placebo) patches applied directly to the painful skin of subjects with
postherpetic neuralgia (PHN) utilizing an 'enriched enrollment' study design. All
subjects had been successfully treated with topical lidocaine patches on a regular
basis for at least 1 month prior to study enrollment. Subjects were enrolled in
a randomized, two-treatment period, vehicle-controlled, cross-over study. The primary
efficacy variable was 'time to exit'; subjects were allowed to exit either treatment
period if their pain relief score decreased by 2 or more categories on a 6-item
Pain Relief Scale for any 2 consecutive days. The median time to exit with the lidocaine
patch phase was greater than 14 days, whereas the vehicle patch exit time was 3.8
days (P ≤ 0.001) . At study completion, 25/32 (78.1%) of subjects preferred
the lidocaine patch treatment phase as compared with 3/32 (9.4%) the placebo patch
phase (P ≤ 0.001) . No statistical difference was noted between the active and
placebo treatments with regards to side effects. Thus, topical lidocaine patch provides
significantly more pain relief for PHN than does a vehicle patch. Topical lidocaine patch is a therapy for PHN that is effective, does not cause systemic side effects, and is simple to use, according to the results of a randomized, enriched-enrollment,
double-blind, placebo-controlled cross over trial.a,b
a Demonstrated over 14 days in a post hoc analysis of a randomized, enriched-enrollment, double-blind, placebo-controlled, crossover trial. Patients enrolled in the study had been using LIDODERM for ≥1 month (ie, enriched enrollment); mean age of 77.4 years and mean PHN duration of 7.3 years. Pain relief was measured using a 6-item verbal scale: 0 (worse), 1 (no relief), 2 (slight relief), 3 (moderate relief), 4 (a lot of relief), and 5 (complete relief). Patients exited the study if their verbal pain relief rating decrease >2 categories for any 2 consecutive days from baseline.
b Results of enriched-enrollment studies can’t be generalized to the entire population; subjects in such studies may be able to distinguish the active drug from placebo based on nontherapeutic features of the treatments.
Overview
Clinical Trial 1 was a double-blind, balanced-random assignment, vehicle patch (placebo)
controlled, two period cross-over trial of 28 days maximum duration. It was designed
to evaluate the safety and efficacy of LIDODERM compared to vehicle patch in patients
with PHN. The primary outcome assessment was the "time to exit" – the time until
a patient discontinued treatment due to inadequate pain relief or due to intolerable side effects. Secondary outcome
measures included patient assessments of the treatment phase that provided the best
pain relief and daily pain relief.
Topical lidocaine relieves postherpetic neuralgia (PHN) more effectively than a vehicle
topical patch
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Clinical Trial Two
Lidocaine patch: medicated plaster treatment for post-herpetic neuralgia, results of a double-blind, placebo-controlled, multinational efficacy and safety trial.
Results: LIDODERM significantly reduced pain intensity from the first application
Authors
Michael C. Rowbotham, MD, Pamela S. Davies, RN MS, Christina Verkempinck, and Bradley S. Galer, MD.
Abstract
Post-herpetic neuralgia (PHN) is a common and often intractable
neuropathic pain syndrome predominantly affecting the elderly. Topical local anesthetics
have shown promise in both uncontrolled and controlled studies. Thirty-five subjects
with established PHN affecting the torso or extremities completed a four-session,
random order, double-blind, vehicle-controlled study of the analgesic effects of
topically applied 5% lidocaine in the form of a non-woven polyethylene adhesive
patch. Up to 3 patches, covering a maximum
of 420 cm2, were applied to cover the area of greatest pain as fully as possible.
Lidocaine containing patches were applied in two of the four 12-h-long sessions,
in one session vehicle patches were applied, and one session was a no-treatment
observation session. Lidocaine containing patches significantly reduced pain intensity
at all time points 30 min to 12 h compared to no-treatment observation, and at all
time points 4-12 h compared to vehicle patches. Lidocaine patches were superior
to both no-treatment observation and vehicle patches in averaged category pain relief
scores. The highest blood lidocaine level measured was 0.1 mg/ml, indicating minimal
systemic absorption of lidocaine. Patch application was without systemic side effect
and well tolerated when applied on skin for 12 h. This study demonstrates
that topical 5% lidocaine in patch form relieves post-herpetic
neuralgia.
Overview
Clinical Trial 2 was a randomized, double-blind study, four-session, 12h, vehicle
patch (placebo) controlled study designed to assess analgesic effects of both drug
and vehicle patch compared to observation only. Primary outcome measures included
patient assessments of pain intensity on a 100-mm visual analog scale (VAS) and
pain relief on a 6-point categorical rating scale.
Test the analgesic efficacy of LIDODERM (lidocaine patch 5%) in reducing pain intensity for PHN patients versus placebo patch and observation
European trial results reaffirm efficacy of lidocaine patch 5% (n=263)1,c,d
PHN patients remained on the lidocaine patch 5% more than twice as long as placebo in the 2-week phase (P=0.0398)
c Double-blind, placebo-controlled, parallel-group, multicenter, enriched enrollment, randomized withdrawal (EERW) European study of 263 patients with a mean pain intensity of 5.9 on the 11-point numerical rating scale (NRS). Study comprised 2 phases: an 8-week, open-label, run-in phase in which patients were treated with lidocaine patch 5% only, followed by a randomized, placebo-controlled, double-blind phase of up to 2 weeks’ duration in which patients either continued with lidocaine patch 5% or were switched to treatment with placebo. The primary efficacy endpoint was time-to-exit at the end of the double-blind phase of the trial due to lack of efficacy assessed on an intent-to-treat (ITT) basis. Time-to-exit was defined as the number of days after randomization when patients achieved a ≥2-point decrease in pain relief (6-point verbal rating scale) on 2 consecutive days of therapy, as compared with mean pain relief in the last week on active treatment before randomization. Median times-to-exit in the 14-day placebo controlled phase were 13.5 days with lidocaine patch 5% vs 9.0 days with placebo patch (ITT population, P=0.1510).
d Results of enriched-enrollment studies can’t be generalized to the entire population; subjects in such studies may be able to distinguish the active drug from placebo based on nontherapeutic features of the treatments.
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