OBJECTIVE: This review was designed to compile the currently available evidence on the prophylactic use of gabapentin in the head and neck cancer patient population.
METHODS: A systematic search was conducted of PubMed, Web of Science, and Google Scholar to identify articles related to the use of prophylactic gabapentin in patients undergoing head and neck cancer therapy. Candidate studies were screened for inclusion and a subsequent bias assessment was conducted by multiple reviewers. Meta-analysis was conducted in cases in which the studies used compatible outcome measures.
RESULTS: Ten studies were identified that met the inclusion criteria and were assessed for bias. Among the four small studies that examined pain prevention, 2 were positive and 2 were inconclusive. Three of the four studies examiniRDng opioid use noted less need for opioids in the treatment arm. Meta-analysis of the pertinent studies showed no difference in feeding tube placement (RD = 0.64%, 95%CI: (- 25.8%, 27.1%), p = 0.962) but substantially less weight loss among those in the treatment arm (p = 0.047).
CONCLUSIONS: Prophylactic gabapentin appears to be a promising treatment option for preventing pain, reducing opioids, and reducing weight loss in patients undergoing head and neck cancer therapy. However, the studies on the treatment to date are small and several have a substantial risk of bias.

BACKGROUND: There are increasing concerns regarding the abusive potential of gabapentinoids putting at risk patients with neuropathic pain requiring long-term pain management. The evidence to support this is rather inconcusive.
OBJECTIVE: This systematic review aimed to evaluate the safety and efficacy of gabapentinoids in the management of neuropathic pain with a focus on randomised controlled trials (RCTs) and categorising the side effects according to the body systems they were affecting.
METHODS: Searches were conducted in MEDLINE (PubMed), EMBASE, Web of Science, PsycoINFO, and CINAHL (EBSCO), and included RCTs to identify and critically appraise studies investigating safety and therapeutic effects of gabapentionoids in adults with neuropathic pain. Data extraction was conducted using an established Cochrane form and the risk-of-bias tool was used in the assessment of quality.
RESULTS: 50 studies (12,398 participants) were included. The majority of adverse events pertained to the nervous system (7 effects) or psychiatric (3 effects) disorders. There were more adverse effects reported with pregabalin (36 effects) than with gabapentin (22 effects). Six pregabalin studies reported euphoria as a side effect, while no studies reported euphoria with gabapentin. This was the only side effect that may correlate with addictive potential. Gabapentioids were reported to significantly reduce pain compared to placebo.
CONCLUSIONS: Despite RCTs documenting the adverse events of gabapentionoids on the nervous system, there was no evidence of gabapentinoid use leading to addiction, suggesting an urgent need to design studies investigating their abusive potential.

Gabapentin (GBP) is a structural analog of gamma-aminobutyric acid (GABA) that is commonly used in palliative care for symptom management indications including neuropathic pain syndromes, hiccups, cough, and anxiety. An uncommon adverse effect of GBP is urinary incontinence (UI). We report the case of a 61-year-old male with metastatic non-small cell lung cancer who developed probable overflow UI while receiving 1200 mg/day of GBP for chemotherapy-induced peripheral neuropathy. The patient self-tapered GBP to 600 mg/day which resolved the overflow UI, but resulted in poorly controlled bilateral foot pain. The palliative care physician rotated the patient to pregabalin 150 mg/day and his bilateral foot pain improved after his regimen was titrated to 200 mg/day. The patient did not experience overflow UI while taking pregabalin despite the similar pharmacology and comparable doses to GBP. We believe this is the first case report to describe subsequent achievement of pain control by substituting pregabalin without recurrence of UI. Healthcare professionals should consider GBP as a potential cause when evaluating patients presenting with new onset overflow UI.

The purpose of this study was to assess the quality of evidence informing on common pharmacologic modalities used in upper extremity complex regional pain syndrome (CRPS).
A literature search was performed for primary prospective trials that reported on the pharmacologic treatment of CRPS type I and II specific to the upper extremity. Thirty-one trials were included and evaluated by 2 independent reviewers according to the Oxford Levels of Evidence (LOE), modified Coleman Methodology Score, and the revised Consolidated Standards of Reporting Trials (CONSORT) score. Cohen\'s kappa coefficient was calculated to measure interrater reliability.
Twenty-two Oxford LOE I and 9 level II trials met the inclusion criteria. Overall, there was high interrater reliability in the Oxford LOE (100% agreement), modified Coleman Methodology Score (87% agreement), and CONSORT score (94% agreement). The pharmacologic interventions with the highest quality of evidence supporting use in treatment of upper extremity CRPS were bisphosphonates and ketamine. Interventions that lack high-quality evidence are tricyclic antidepressants (TCAs) and topical dimethyl sulfoxide (DMSO). Pharmacologic agents that remain inconclusive are calcitonin, gabapentin, mycophenolate, probiotics, steroids, nonsteroidal anti-inflammatory drugs, vitamin C, and N-acetylcysteine. Agents with limited benefit are mannitol, isosorbide dinitrate, guanethidine, and morphine.
Based on the evidence evaluated in this study, bisphosphonates should be considered as a first-line medication in the treatment of CRPS. In patients presenting with chronic or refractory CRPS, strong consideration should be given for the use of ketamine. Adjunct treatment in the acute setting should include TCAs and/or topical DMSO.

Chronic pelvic pain (CPP) affects 2.1-24% of women, causing physical and psychological damage to women around the world. Based on the efficacy of gabapentin in the treatment of chronic pain, we conducted this study to evaluate the efficacy and safety of gabapentin in reducing pain in women with CPP.
Systematic searches were performed in the electronic databases of PubMed, Embase, Web of Science, Scopus, Cochrane, and Clinicalkey databases. Studies focused on comparing the efficacy of gabapentin and placebo in the treatment of female CPP patients were included. RevMan 5.4 was used to analyze the results and risk of bias. Two investigators independently selected eligible studies and extracted related pain scores and side effects for meta-analysis.
In total, 4 RCTs were enrolled in the meta-analysis, totaling 425 patients. Among patients receiving gabapentin, the average pain scores in 3 and 6 months were significantly lower than those in the placebo group(p < 0.00001). The results showed that there was no statistical difference between gabapentin and placebo in the reduction of pain scores from baseline(p = 0.41). The incidence of side effects in the gabapentin group was significantly higher than that in the placebo group (p < 0.00001).
This systematic review and meta-analysis demonstrated that for women with CPP, gabapentin was significantly different from placebo in average pain scores at 3 and 6 months. However, the two drugs did not differ in the reduction in pain scores from baseline. Gabapentin can bring more significant side effects, whether they are common side effects or serious side effects.

γ-Aminobutyric acid (GABA) plays an important role in regulating neuronal excitability. Four structurally related drugs to GABA including pregabalin (PGB), gabapentin (GBP), vigabatrin (VGB), and baclofen are used for the treatment of central nervous system disorders. These drugs are small aliphatic molecules having neither fluorescent nor strong absorbance in the ultraviolet/visible region; therefore, direct determination of these analytes by optical methods is difficult. Additionally, their high boiling point makes gas chromatography impossible. Accordingly, the amine or acid moiety in these drugs is derivatized in order to improve their selectivity and sensitivity during determination in the biological samples. This review focuses on derivatization based methods and their different reactions for determination of PGB, GBP, VGB, and baclofen in the biological samples and pharmaceutical preparations reported between 1980 and 2020. High-performance liquid chromatography methods coupled with different detectors are a commonly used methods for determination of GABA analogs after derivatization. These methods cover 38.89% of all developed methods for determination of GABA analogs.

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The aim of this systematic review was to determine the efficacy of gabapentin (GBP) in the treatment of pain of  idiopathic trigeminal neuralgia (TN). A comprehensive literature search was conducted using the Cumulative Index of Nursing and Allied Health Literature (EBSCO Industries), Emcare (Ovid), Medline (Ovid), Medline (PubMed), Scopus (Elsevier) and Web of Science (Clarivate Analytics). The inclusion criteria comprised randomized controlled trials of GBP as a monotherapy in the treatment of idiopathic TN in adult participants and publications in English. All other study methodologies were excluded. The search yielded 1472 articles, and after exclusion, 11 full-text articles were eligible for full-text analysis. Only two studies met the inclusion criteria. There is insufficient evidence either to support or refute the efficacy of GBP in the management of idiopathic TN. Therefore, further well-designed placebo-controlled trials are required to confirm the efficacy of GBP in managing TN pain as a single therapy.

The gabapentinoids gabapentin and pregabalin have been related to addiction citing pharmacovigilance data, some case presentations and increasing reports mainly from methadone maintenance treatment programs or emergency medicine. Most of these reports were based on patients with another current or previous substance use disorder (SUD). According to the ICD-10 dependence criteria, physical dependence (withdrawal symptoms, tolerance) was reported most frequently alongside regular use of gabapentinoids. Far less patients showed key symptoms of behavioral dependence (craving, loss of control, or addictive behavior). Through a literature review, we found 2 and 13 case reports about gabapentionoid-seeking behavior or craving for gabapentin and pregabalin, respectively. Those patients without a history of another SUD, but being behaviorally dependent on gabapentinoids, deemed more appropriate to reflect the true addictive power of these drugs. We found solely 4 such cases, all referring to pregabalin and none for gabapentin. Taking into account that gabapentinoids have become widely distributed and easily obtainable via the internet or black-markets, one would expect many more of these cases, if gabapentinoids had considerable addictive power. Moreover, we are not aware of any patient who sought detoxification treatment owing to the misuse of gabapentinoids. Unlike for traditional psychoactive drugs, there is only very scarce evidence for gabapentinoids to be misused in a long-term manner and to be rewarding and reinforcing in animal experiments. Further, we assessed the hazardous potential of gabapentin and pregabalin in relation to that of traditional substances of abuse. Altogether, we support the view that gabapentinoids are quite rarely addictive in the general population. In patients with a history of SUD, however, gabapentinoids (notably pregabalin) should avoided or, if thought to be beneficial, administered with caution by using a strict prescription and therapy monitoring.

BACKGROUND: Negative myoclonus is a jerky, brief, and sudden interruption of voluntary muscle contraction. Although gabapentin and pregabalin have been reported to induce positive myoclonus in some patients with impaired renal function, there are only a few studies describing pregabalin- or gabapentin-induced negative myoclonus. This study reviewed patients who had developed pregabalin- or gabapentin-induced negative myoclonus.
METHODS: We collected the patients with negative myoclonus who were referred to the department of neurology at a university-affiliated hospital and selected pregabalin- or gabapentin-induced negative myoclonus. Then reviewed the literature with respect to pregabalin- or gabapentin-induced negative myoclonus.
RESULTS: A total of 77 patients with negative myoclonus were reviewed. Among them, 21 neuropathic pain patients who were prescribed and developed negative myoclonus induced by pregabalin (9 cases) or gabapentin (12 cases). To prove causality of the drug, probable and certain level of category according to the WHO-UMC criteria were recruited. Of the 21 patients, 3 had impaired renal function, while 18 had normal renal function. Review of the literature identified 7 further cases (6 had normal renal function) with pregabalin- or gabapentin-induced negative myoclonus.
CONCLUSIONS: Pregabalin- and gabapentin-induced negative myoclonus can develop even in patients with normal renal function. Physicians should keep in mind the possibility of patients developing negative myoclonus under treatment of pregabalin or gabapentin even in short period of time and with low dosage, and in the normal range of renal function. Further prospective study investigating incidence and risk factors is warranted.