Subjects

Eighteen subjects were recruited and fifteen of these subjects completed the study. The subject population was predominantly female (80%) and elderly (mean age: 68.3 years, age range: 49-90 years). The duration of PHN ranged from 6 to 38 months with a mean duration of 16.7 months. Before the study entry, all 15 subjects had been given trials of anticonvulsant medications. Eight subjects had also tried NSAIDS, 6 had tried tricyclic antidepres­sants and 3 had tried opioids. However, they had either obtained inadequate partial pain relief or had experienced intolerable side effects with these traditional pharmacologic therapies. The subjects applied an average of 2.13 (+ 1.2SD) lidocaine patches per day (Table 1).

tab1

Efficacy

At the time of pre-treatment, the mean pain intensity VAS scores were similar for all sessions (61.9 + 18.4 mm of lidocaine, 61.1 ± 18.7 mm of vehicle; £>=not significant) (Table 2). The mean VAS scores were constantly lower in the lidocaine patch sessions than those of the vehicle patch sessions after the start of treatment (Fig. 1). The 5% lidocaine patch was statistically superior to the vehicle patch for pain reduction at the time points 12 hr, 24 hr, 48 hr and 72 hr (individual time points: p<0.001 to £>=0.015). The greatest reduction in the mean VAS pain intensity was 18.4 mm at the 48 hr time point during the lidocaine session, and 8.3 mm at the 24 hr time point during the vehicle session. When compared with baseline, application of a lidocaine patch significantly reduced pain at the times points 12 hr, 24 hr, 48 hr, and 72 hr (indi­vidual time points £><0.001 to £>=0.033). The vehicle patch also had a significant effect on pain reduction compared to pre-treatment at the times 12 hr, 24 hr, 48 hr (individual time points £>=0.003 to £>=0.042). The average category pain relief scores of the lidocaine patch sessions were higher than those of the vehicle patch session at all time points from 12 hr to 96 hr (Table 3). The lidocaine patch application produced statistically higher average pain relief scores than the vehicle patch at all time points (individual time points: £><0.001 to £>=0.04). The highest average relief rating score of the lidocaine patch session was 2.7 ± 0.65 at 24 hr after applica­tion, which was between ‘slight’ and ‘moderate’ improvement. The average relief rating score of the vehicle patch session at 24 hrs after treatment was 1.7 ± 0.45, which was between ‘no change’ and ‘slight improvement’; this showed that the vehicle patch also had a limited effect on pain reduction. cialis professional online

Table 2. Mean Pain Intensity VAS Scores at Each Time Point

0
hr

12
hr

24
hr

48
hr

72
hr


9t


5
hr

LP VP

61.9±
18.4 61.1
±18.8


44.7 ± 17.2 54.1
± 16.8


45.5 ± 17.0 52.8
± 18.6


43.5 ± 18.0 54.4
± 18.1


49.6 ± 18.2 57.2
± 17.8


55.3 60.1


± 17.8
± 17.0

Side effects and safety

The 5% lidocaine patch was well tolerated. The only side effect reported in this study was mild skin irritation during the first lidocaine patch session in one subject. The irritation subsided quickly without treatment and did not recur at the next session.

Table 3. Mean Category Pain Relief Scores at Each Time Point


12hr


24hr


41


3hr


72hr


96hr


LP


2.4± 1.1


2.7± 0.65


2.6


± 0.67


2.2± 0.99


1.9± 1.1


VP


1.7± 0.45


1.5± 0.7


1.27


± 0.58


1.2± 0.92


1.2± 0.56