Gabapentin as a Adjuvant Analgesic in Central Pain Syndrome

Han, Tae Hyung; Kwon, Min Ah

Abstract

BACKGROUND: This study was undertaken to investigate the analgesic efficacy and safety of gabapentin in central pain syndrome.
METHODS
With a diagnosis of central pain syndrome, a total 24 patients were accumulated in the outpatient pain clinic. Patients had been stabilized in their analgesic regimen at least four weeks prior to the study. Anticonvulsants, if taken, were discontinued for two weeks for wash-out. Pretreatment baseline pain scores (visual analog scale and pain intensity score) were obtained. Oral administration of gabapentin 300 mg was started in all patients. Initial doses were given from 300 mg per day with gradual titration over two weeks until 1) the onset of analgesic effect, 2) the maximum of 2,400 mg per day, and 3) the onset of intolerable side effects. Dosage was adjusted weekly. At the four-week study end point, VAS, PIS, pain improvement scores judged by family members, drug efficacy, tolerability and overall evaluation were assessed. The incidence of side effects was also noted.
RESULTS
Fifteen patients dropped out due to various reasons. Data was collected from 9 patients (male = 4, female = 5). Among these, 3 had strokes and 6 spinal cord lesions due to trauma, cancer metastasis or syringomyelia. The average disease duration was 4.2 years. Analgesic onset was within two weeks and the average dose taken was 477.7 mg. At the end of the study, the VAS score and PIS revealed significant pain relief. These results were objectively reflected in pain improvement scores observed by family members. The majority scored good or excellent in all scales of drug evaluation. Sedation was the most frequently reported side effect. Others included dry mouth, weakness, and diarrhea, which were spontaneously resolved with lower dose maintenance.
CONCLUSIONS
Gabapentin showed analgesic effect for central pain syndrome at a lower dose range than any other neuropathic pain syndromes. It appears to have different analgesic dose requirements in this difficult pain syndrome.