What is the role of gabapentin in themanagement of hemodialysis-associated itching? A double-blind,placebo-controlled study crossover study was performed to see the effectivenessof gabapentin on patients with uremic pruritus. Twenty-five adult patients (14men and 11 women) were enrolled in the study. The patients were 18 years old orabove.
The patients were on hemodialysis, which was used for 4-5 hours threetimes a week with a polysuphone dialyzer. All patients in this study hadhistories of pruritus of greater than 8 weeks duration and none of them haddermatological, liver or metabolic disease associated with pruritus. Thepatients used a visual analogue scale to rate the level of their pruritus daily.The scale had a horizontal line marked 0 (non-pruritus) to 10 (severe pruritus).
During the experiment, the patients received gabapentin therapy for 4 weeksfollowed by 4 weeks of placebo or 4 weeks of placebo followed by gabapentin for4 weeks. There was a week washout period between each phases. The patients hadto submit their pruritus scores the week before the trial, the active treatmentphase, the placebo phase, and the intervening washout period. At the end of hemodialysissessions, 300 mg Gabapentin or placebo was given to patients three times aweek. The experimenters used the mean ofthe score to determine the actual score of each period. 1The data givenbefore and after the experiment were given and analyzed. The mean pruritusscore prior to the experiment came out to be 8.
40.94 (range:7-10). The score decreased to 7.
6range: 2-10;P=0.098) after placebo administration. The mean pruritus score returned to thebaseline levels (7.91.1) after the1-week washout period.
The mean score decreased to 1.21.8 (range 0-8;P=0.0001) after gabapentin administration. During the experiment, the patientsexperienced mild to moderate side effects such as somnolence, dizziness, andfatigue from taking gabapentin. Gabapentin was proven to be an effectivetherapy for uremic pruritus in hemodialysis patients.
Not only this study hadfound evidence that gabapentin can have a positive effect on patients with hemodialysisitching, there was another study suggested that gabapentin could be used as asafe and effective treatment for uremic itch. Another studywas done as a double blind, placebo-controlled trial. Thirty-four adultpatients (16 males and 18 females) participated in this study. The mean age ofthese patients was 62 years old. Patients with skin disease other than uremicpruritus were excluded from the study. During the experiment, the patients wererandomly assigned to either gabapentin 400 mg or placebo group.
The placebo wasan emptied gabapentin capsule filled with flour. The study involved with thepatients receiving four weeks of treatment with either gabapentin 400 mg orplacebo administered twice weekly after hemodialysis sessions. Similar to the firststudy, a visual analogue was used for patients to record their pruritus scores.The pruritus scores were compared between the group receiving Gabapentin 400 mgand the placebo group. After the four weeks, they found that the mean pruritusscore decreased in both groups. Before the experiment, the experimenterscollected the pain scores from the patients. The mean pruritus score atbaseline was 7.2 2.
3 (range3-10). As a result, the pruritus mean in the gabapentin group was 6.72.6 and placebogroup was 1.51.8, (p < 0.001)after the four weeks of treatment. The mean in pruritus scores after the studyperiod was compared between two groups with two-sample independent t-tests, andthe statistical analysis was performed using SPSS version 11.
0 software. Thisstudy supports the idea that gabapentin can effectively alleviate pruritus in uremicpatients.2After analyzingthese articles, these two studies showed similar experimental design. For instance,both studies were double-blinded and they compared the effectiveness betweenplacebo and gabapentin. In addition, both studies used visual analogue forpatients to record their pruritus scores. The differences would be that thesecond study had a larger sample size, used a higher dose of gabapentin (400mg), and was a shorter experiment (4 weeks). After reviewingthese studies, there were some strengths and weaknesses of these articles thatcan be taken into consideration.
For instance, one of the strengths would bethat the first study was a random, double-blinded, crossover study. This studymethod reduced the chance of bias. In addition, the duration of the experimentwas reasonable.
The idea of having the patients be on four weeks of gabapentinfollowed by four weeks of placebo or vice versa showed a difference theeffectiveness between the placebo and gabapentin. Nevertheless, one of theweaknesses would be that the first article did not provide enough information ongraphs. For example, Figure 1 did not show a clear comparison between thevisual analogue scale scores. The graph should have a more descriptive legend. Thegraph can be better represented with a bar graph instead of a plot graph. Anotherfactor that limited this study was that the pruritus scores were measured oncea day and the scores were only subjective indications of the level of itching.
1Similar to the first study, the second study was also a double blinded,placebo-controlled study which reduced bias. A weakness would be that thepruritus scores were also measured based on patients’ sense of itchiness. Thismeasurement is subjective because the level of itchiness may be different forother people.2There werestudies that demonstrated that gabapentin can alleviate pruritus by comparing Gabapentinand placebo.
Overall, the two studies that were mentioned showed that gabapentinhad a greater effect on pruritus than a placebo drug.