Intravenous Lidocaine in Chronic Neuropathic Pain: A Systematic Review.

OBJECTIVES: A systematic review of original research articles was conducted to evaluate the safety and efficacy of lidocaine infusion in the treatment of adult patients with chronic neuropathic pain. MATERIALS AND METHODS: Original research from 1970 to September 2021 describing adult patients with chronic neuropathic pain receiving at least 1 dose of intravenous lidocaine was included. Extracted data included study design, sample size, patient demographics and comorbidities, etiology and duration of pain, pain intensity scores, time to pain resolution, lidocaine dose and administration frequency, lidocaine serum concentration, and adverse events. Each study was evaluated for level of evidence using the 2017 American Association of Neurology classification system. RESULTS: Twenty-seven studies evaluating lidocaine infusion treatment in chronic neuropathic pain met inclusion criteria. One class I study was identified for patients with neuropathic pain due to spinal cord injury . Two Class II studies were identified, one describing neuropathic pain due to peripheral nerve injury and another due to diabetic neuropathy. Across all studies, study design, participants, and experimental interventions were heterogenous with wide variation. DISCUSSION: This qualitative review found insufficient, heterogenous evidence and therefore no recommendation can be made for lidocaine infusion treatment in patients with chronic neuropathic pain due to spinal cord injury, peripheral nerve injury, diabetic neuropathy, postherpetic neuralgia, or complex regional pain syndrome type II. Larger randomized, double-blind, placebo-controlled studies are required to further establish the efficacy of lidocaine infusion in patients with these etiologies of chronic neuropathic pain.

Physician Renewal of Chronically Prescribed Controlled Substances Based on Urine Drug Test Results.

Objective: The effect of specific urine drug testing (UDT) results on physician prescribing habits has not been well described. The primary objective was to report renewal rates of chronically prescribed controlled substances based on types of inconsistent UDT results. Methods: We conducted a retrospective chart review over a 5-month period comparing prescription renewals rates for patients with consistent versus inconsistent UDTs. Inconsistent UDTs were defined by prescribed drug not detected or the presence of heroin, cocaine, nonprescribed opioids, nonprescribed benzodiazepines, or marijuana. Results: Of the 474 UDTs reviewed, 214 (45.1%) were inconsistent. The most common findings among inconsistent UDTs, including overlapping results, were prescribed drug not detected (26.8%) and the presence of marijuana (20.7%), nonprescribed opioids (9.9%), and nonprescribed benzodiazepines (6.1%). In contrast, cocaine (5.5%) and heroin (0.4%) were less likely to be found on UDTs for this population. The relative risk (RR) of prescription renewal was 0.64 (95% CI 0.57-0.71) for inconsistent UDTs versus consistent UDTs. Within the inconsistent UDTs, the renewal rates when marijuana (79.6%) or nonprescribed opioids or benzodiazepines (63.6%) were present were much higher than when heroin or cocaine were present (0.0%; P < .001). Patients whose prescribed controlled substance was not detected had a 55.8% renewal rate. Conclusions: Prescription renewal rates were high when patient UDTs contained nonprescribed marijuana, opioids, and benzodiazepines, or when the prescribed drug was not detected. Prescription renewal rates were low when illicit drugs, such as heroin and cocaine, were detected.