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abstracts & posters

Gabapentin for Pain in Sickle Cell Disease: Results of a Randomized Phase ll Clinical Trial

key information

source: American Society of Pediatric Hematology/Oncology

summary/abstract:

Background:
Pain in sickle cell disease (SCD) can have a significant neuropathic component. Therapies targeting neuropathic pain have not been extensively studied in this setting. We report results of a randomized controlled trial evaluating utility of gabapentin for acute vaso-occlusive crisis (VOC) pain.

Objectives:
The primary objective was to evaluate efficacy of gabapentin when added to standard therapy for acute VOC pain. Main outcome was as >33% reduction in pain scores between presentation (baseline) and assessment at 3 hours post-study drug administration. The secondary objective was to compare opioid consumption as morphine equivalent dose (MED, mg/kg) between baseline and 3 hours, in the gabapentin versus placebo groups.

Design/Method:
This was a phase II double-blind placebo-controlled study. Patients with SCD, ages 1 to 21 years, presenting with VOC pain were enrolled and randomized to receive either a single oral dose of gabapentin, 15 mg/kg or placebo in addition to standard treatment. Pain scores and opioid requirement were compared between treatment arms.

Results:
Ninety patients (35 females, 59 males) were randomized, 45 in each arm. Forty-two and forty-four participants were evaluable in gabapentin and placebo arms, respectively. Pain scores at presentation were similar for both groups, mean (standard deviation/SD) 7.8 (1.8). In gabapentin arm, 67.5% (n=27) patients experienced >33% decrease in pain from presentation to 3 hours post treatment versus 59.5% (n=25) in placebo arm (p=0.23, Z-test). The overall mean (SD) MED (mg/kg) was 0.16 (0.10), with no significant difference between gabapentin (median 0.12, SD: 0.09) and placebo arms (median 0.13, SD: 0.11) (p = 0.897, Wilcoxon rank sum test). Absolute decrease in pain scores from baseline to admission or discharge from acute care was higher in gabapentin (median 1.0, SD: 3.1) as compared to placebo arm (median 0.5, SD: 2.3), but not significant (p=0.38, Wilcoxon rank sum test). However, for patients with HbSS genotype absolute pain decrease was significantly greater in gabapentin (mean 5.9, SD: 3.5) versus placebo arm (mean 3.6, SD: 3.3) (p = 0.03, t-test).

Conclusion:
Although not significant, a greater proportion of patients achieved clinical improvement in pain when gabapentin was added to standard therapy. Gabapentin also resulted in greater decrease in pain scores, particularly in patients with HbSS. Thus, gabapentin can be a useful adjunct to standard management, particularly for patients with HbSS, who generally have a more severe phenotype and often with neuropathic pain features. Future studies with larger cohorts are needed to confirm these findings.

 

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