Case Series: Synergistic Effect of Gabapentin and Adjuvant Pregabalin in Neuropathic Pain.

Gabapentin and pregabalin both exert high affinity to the α2δ subunit of the voltage-gated calcium channels which inhibits excitatory neurotransmitter release. The synergistic mechanism was described in rats given combinations of gabapentin and pregabalin. In this case series, we described 2 cases which may illustrate the synergistic effect of gabapentin and pregabalin in treatment resistant neuropathic pain. Low dose pregabalin was added to therapeutic gabapentin to achieve appreciable pain reduction in one case and improved quality of life in another case. Further research with more enrollment and longer study duration may help elucidate the appropriate dosing and potential associated side effects.

Assessment of outcomes following high-dose opioid tapering in a Veterans Healthcare System.

OBJECTIVE: To assess the impact of tapering of chronic high dose opioid therapy in veterans prompted by the implementation of the Opioid Safety Initiative in 2013. DESIGN: IRB and VA Office of Research and Development-approved retrospective, observational chart review. SETTING: North Florida/South Georgia Veterans Health System Patients: Veterans on high dose opioid therapy (≥300 mg of morphine equivalents per day) for chronic non-cancer pain as of 1/1/2012 with an opioid agreement discontinuation note documented in the medical record were included. Veterans treated for cancer pain or under palliative care were excluded. OUTCOMES: Descriptive outcomes include rate of opioid discontinuation, average duration of tapering, and rate of relapse. Differences before and after discontinuation assessed include healthcare utilization, monitoring via urine drug screens and state prescription drug monitoring program (PDMP) queries, non-opioid analgesics, benzodiazepines, and non-pharmacologic modalities. RESULTS: Forty-three patients were included. The mean duration of therapy was 7.8 years and 81.4 percent were on methadone prior to tapering. Opioids were tapered to discontinuation in 28 patients (65 percent) with long-term abstinence in 71 percent. The mean duration of tapering was 81 days and the median/mode was 30 days. Statistically significant differences after tapering include decreased PDMP queries, increased non-opioid analgesics, decreased benzodiazepine prescriptions, and increased use of mental health services (p < 0.05). There were zero adverse outcomes identified in those tapered and one death in the group who sought non-VA care for continuation. CONCLUSIONS: This study suggests that moderate speed tapering in high-risk veterans on chronic high-dose opioid therapy can be achieved, but caution is warranted in ensuring adequate follow-up and monitoring. Clinical pharmacy services may improve tapering outcomes by providing more frequent follow-up, monitoring via state PDMP queries to identify patients who have relapsed, and dispensing naloxone for increased safety.