Addition Of Gabapentin Research Articles

Pharmacokinetic, sedative, and physiological effects of oral compounded formulations of trazodone alone or in combination with gabapentin in male cats.

Trazodone and gabapentin are common oral sedatives in cats, used alone or combined, but no pharmacokinetic studies exist for trazodone in this species. The objective of this study was to determine the pharmacokinetics of oral trazodone (T) alone, or in combination with gabapentin (G) in healthy cats. Cats (n = 6) were randomly allocated to receive T (3 mg/kg) intravenously (IV), T (5 mg/kg) orally (PO), or T (5 mg/kg) and G (10 mg/kg) PO with a 1-week washout period between treatments. Heart rate, respiratory rate, indirect blood pressure, and level of sedation were assessed, and venous blood samples were collected serially over 24 h. Analysis of plasma trazodone concentration was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Oral T administration resulted in a bioavailability of 54.9(7-96)%, and 17.2(11-25)% when administered with G. Tmax 0.17 (0.17-0.5) and 0.17 (0.17-0.75) h; Cmax 1.67 ± 0.91 and 1.22 ± 0.54 μg/mL, AUC 5.23 (2.0-18.76) and 2.37 (1.17-7.80) h*μg/mL; T1/2 5.12 ± 2.56 and 4.71 ± 1.07 h; for T and TG, respectively. Sedation was significant when compared to baseline in all groups from 20 or 45 min to 8 h indicating some lag between peak plasma concentration and sedative effects. Physiological variables remained within normal limits. This study concludes that oral trazodone is rapidly absorbed in healthy cats. Addition of gabapentin did not result in more profound sedation, showing no clinical advantage of combining these drugs in this study population.

Effect of gabapentin on length of stay, opioid use, and pain scores in posterior spinal fusion for adolescent idiopathic scoliosis: a retrospective review across a multi-hospital system

BackgroundGabapentin has been adopted in Enhanced Recovery After Surgery protocols as a means to reduce opioid consumption while maintaining adequate post-operative analgesia. The purpose of our study was to review and compare changes in length of stay, opioid use, and patient reported pain scores after the addition of gabapentin into five, distinct pain protocols for posterior spinal fusion in adolescent idiopathic scoliosis.MethodsA retrospective review was completed using a database of electronic medical data from a single pediatric orthopedic healthcare system that was queried for patients with adolescent idiopathic scoliosis who underwent first-time posterior spinal fusion. Perioperative data including demographics, hospital length of stay, surgical details, opioid use, patient reported pain scores, and non-opioid analgesic use were collected.ResultsFrom December 2012 to February 2019, 682 hospitalizations for posterior spinal fusion in adolescent idiopathic scoliosis were identified with complete inpatient data; 49% were administered gabapentin. For the gabapentin cohort, the system saw no statistically significant effect on length of stay or pain averaged over POD#0–3. Opioid use was statistically lower averaged over POD#0–3. Individual sites saw variation on length of stay and opioid use compared to the system.ConclusionIn conclusion, system-wide data showed gabapentin containing protocols reduced opioid use while maintaining clinically equivalent analgesia. However, variations of individual site results make it difficult to conclude the degree to which gabapentin were responsible for this effect.

817: EFFECT OF GABAPENTIN AND METHOCARBAMOL ON LENGTH OF STAY IN PATIENTS WITH TRAUMATIC RIB FRACTURES

Introduction: Use of opioid-sparing agents in patients with traumatic rib fractures is associated with positive outcomes such as reduced intensive care unit (ICU) length of stay (LOS) and opioid exposure. While multiple studies have aimed to evaluate analgesic interventions for rib fractures, no specific bundled combination of analgesia has demonstrated superiority. The objective of this study was to characterize the effect of non-opioid analgesic agents (methocarbamol and gabapentin) as part of a multimodal pain regimen including acetaminophen and lidocaine patches on ICU LOS, hospital LOS, and opioid utilization in patients with traumatic rib fractures. Methods: This was a retrospective cohort study of patients admitted to a surgical ICU at a level I trauma center. Of these, patients with at least one rib fracture were eligible for inclusion. Patients were divided between APAP-lidocaine-methocarbamol and APAP-lidocaine-gabapentin groups. The primary endpoint, ICU LOS, and secondary endpoint of hospital LOS were analyzed by log-rank test. Average cumulative oral morphine equivalents (OME) was analyzed by t-test. Results: 129 patients were included in study analysis: 98 in the APAP-lidocaine-gabapentin group and 31 in the APAP-lidocaine-methocarbamol group. There were no differences in age, sex, race, type of injury, mechanism of injury, and injury severity. The median ICU LOS was similar between APAP-lidocaine-gabapentin (2 +/- 3.2 days) and APAP-lidocaine-methocarbamol (1.8 +/- 1 days) (p=0.23). There was no difference in median hospital LOS between APAP-lidocaine-gabapentin (3.7 +/- 3.8 days) and APAP-lidocaine-methocarbamol (3.8 +/- 1.9 days) (p=0.72). There was also no difference in average cumulative opioid exposure between APAP-lidocaine-gabapentin (85.1 +/- 40.5 mg) and APAP-lidocaine-methocarbamol (84.4 +/- 46.2 mg) (p=0.98). Conclusions: The addition of gabapentin or methocarbamol to acetaminophen plus topical lidocaine patches did not appear to affect the LOS or opioid exposure in this cohort of patients with traumatic rib fractures.

Gabapentin for pain control during same-day dilation and evacuation: A double-blind randomized controlled trial

Introduction Scant research evaluates pain management during dilation and evacuation (D&E). Gabapentin has emerged as an effective adjunct for peri-operative pain control. We investigated the effect of gabapentin on pain during D&E. Method We conducted a randomized controlled double-blinded trial among patients undergoing same-day D&E at 14 through 19 weeks gestation under intravenous moderate sedation. Participants were randomized 1:1 to oral gabapentin 600 mg or placebo, administered after misoprostol cervical preparation. Pain was assessed by 100-mm visual analog scale. We assessed satisfaction with pain control, nausea, vomiting, and anxiety using 5-point Likert scales and State Trait Anxiety Inventory. The study was powered to detect a 30% reduction in maximum operative pain (13-mm) assessed five minutes postoperatively. Results We enrolled 126 participants and randomized 61 to gabapentin and 65 to placebo, with study medication administered a mean of 3.5 hours preoperatively (range 1.2–6.2 h). No difference was observed in baseline demographics, parity, or gestational age. Gabapentin was associated with reduced pain after speculum insertion (45 vs 56 mm, p = 0.03) and during uterine aspiration (56 vs 71 mm p = 0.003), compared to placebo. Thirty-minutes post-procedure, the gabapentin group had lower pain (12 vs 23 mm, p=0.008) and higher satisfaction (p = 0.01). Median fentanyl dose was 25 mcg lower in the gabapentin group (75 vs 100 mcg, p = 0.005). Maximum operative pain did not differ between groups (41 vs 49 mm, p = 0.2). Versed dose, nausea, vomiting, and anxiety did not differ between groups. No serious adverse events occurred nor was sedation reversal required. Conclusions The addition of gabapentin to moderate sedation during D&E resulted in reduced intra-operative pain, lower fentanyl dosing, and increased satisfaction with pain control. However, maximum pain reported after the procedure was not different.

MP43-15 EXPLORING ENHANCED RECOVERY AFTER SURGERY PROTOCOL FOR URETEROSCOPY

INTRODUCTION AND OBJECTIVE: Enhanced recovery after surgery (ERAS) protocols originated in colorectal surgery and involve a multimodal, multidisciplinary approach to perioperative care. ERAS protocols have been applied to outpatient ureteroscopy with goals of improving the perioperative experience and decreasing exposure to perioperative opioids in this high risk population. The relative impact of various protocol elements is unclear. It is the possible that patient and staff education may be as, or more, effective than medications in opioid reduction. To explore this issue, we instituted changes in pre-operative medications without any other changes to “usual care” in attempt to isolate medication effects. METHODS: Within a metropolitan health system, patients scheduled for outpatient ureteroscopy received usual care in pre-operative process, anesthesia, surgery, and recovery process. Over time, preoperative orders evolved from no analgesics (NO), to preoperative ketorolac (15 mg IV) plus acetaminophen (1000 mg PO) (KA), to ketorolac, acetaminophen, plus gabapentin (600 mg PO) (KAG). Primary outcome was administration of opioids in recovery process, which continued to be delivered according to nursing protocol based on patient reported comfort RESULTS: Patient groups consisted of 190 baseline NO, 180 KA, and 131 KAG and was implemented over time (Figure 1). Age (y±SD) (54.9±16.2, 53.9±16.2 53.6±16.6; p=0.74) and sex (% male) (44%, 53%, 50%; p=0.285) were similar in NO, KA, and KAG respectively. Procedure length was slightly faster in KAG (19.9±10.8 min) than NO (23.9±15.5) and KA (24.5±13.4) (p=0.008). Patients completing recovery process without any opioids increased from 50% in NO to 62% with pretreatment with KA (p=0.022). The opioid-free rate remained similar after adding gabapentin (66%; p=0.511) CONCLUSIONS: Administering pre-operative ketorolac and acetaminophen was associated with decreased rate of immediate post-operative opioid use. Addition of gabapentin was not associated with further improvement. It is deduced that patient and staff education are important elements in achieving true zero opioid use in the recovery phase, as has been reported by Grindley et al J Urol, 201:e549, 2019.Source of Funding: None

Use of Gabapentin in Posterior Spinal Fusion is Associated With Decreased Postoperative Pain and Opioid Use in Children and Adolescents.

Retrospective cohort study. The objective of this study was to examine associations of gabapentin use with inpatient postoperative daily pain scores and opioid use in children undergoing PSF for AIS. Gabapentin use in posterior spinal fusion (PSF) postoperative pain management for adolescent idiopathic scoliosis (AIS) is increasingly common in order to decrease opioid use and improve pain control, though there is conflicting data on dosing and effectiveness to support this practice in real world settings. Retrospective cohort study of children aged 10 to 21 years undergoing PSF for AIS between January 2013 and June 2016 at an urban academic tertiary care center. Adjuvant gabapentin exposure was defined as at least 15 mg/kg/d by postoperative day (POD) 1 with an initial loading dose of 10 mg/kg on day of surgery. Primary outcomes were daily postoperative mean pain score and opioid use [morphine milligram equivalents/kg/day(mme/kg/d)]. Secondary outcomes were short and long-term complications. Among 129 subjects (mean age, 14.6 y, 74% female, mean coronal cobb, 55.2 degrees), 24 (19%) received gabapentin. Unadjusted GABA exposure was associated with significantly lower opioid use on POD1 and 2 (49% and 31%mme/kg/d, respectively) and lower pain scores (14%) on POD2. Adjusting for preexisting back pain, preoperative coronal Cobb angle, and site, GABA use was associated with significantly lower mean pain scores on POD1 through POD3 (-0.68, P=0.01; -0.86, P=0.002; -0.63, P=0.04). Gabapentin use was also associated with decreased opioid use on POD1 and POD2 (-0.39mme/kg/d, P<0.001; -0.27, P=0.02). There was no difference in complications by gabapentin exposure. Addition of gabapentin as adjuvant therapy for adolescent PSF, beginning on day of surgery, is associated with improved pain scores and decreased opioid use in the first 48 to 72 hours postoperatively. This is a retrospective cohort study, classified as Level III under "Therapeutic Studies Investigating the Results of a Treatment."

Combination therapy of levetiracetam and gabapentin against nonconvulsive seizures induced by penetrating traumatic brain injury.

Posttraumatic seizures are a medical problem affecting patients with traumatic brain injury. Yet effective treatment is lacking owing to the limitations of antiepileptic drugs (AEDs) applicable to these patients. In this study, we evaluated the dose-response efficacy of levetiracetam (12.5-100.0 mg/kg) and gabapentin (1.25-25.0 mg/kg) administered either individually or in pairs at fixed-dose ratios as a combination in mitigating posttraumatic nonconvulsive seizures induced by severe penetrating ballistic-like brain injury (PBBI) in rats. Seizures were detected by continuous electroencephalogram (EEG) monitoring for 72 hours postinjury. Animals were treated twice per day for 3 days by intravenous injections. Both levetiracetam (25-100 mg/kg) and gabapentin (6.25-25 mg/kg) significantly reduced PBBI-induced seizure frequency by 44% to 73% and 61% to 69%, and seizure duration by 45% to 64% and 70% to 78%, respectively. However, the two drugs manifested different dose-response profiles. Levetiracetam attenuated seizure activity in a dose-dependent fashion, whereas the beneficial effects of gabapentin plateaued across the three highest doses tested. Combined administration of levetiracetam and gabapentin mirrored the more classic dose-response profile of levetiracetam monotherapy. However, no additional benefit was derived from the addition of gabapentin. Furthermore, isobolographic analysis of the combination dose-response profile of levetiracetam and gabapentin failed to reach the expected level of additivity, suggesting an unlikelihood of favorable interactions between these two drugs against spontaneously occurring posttraumatic seizure activities at the particular set of dose ratios tested. This study was the first attempt to apply isobolographic approach to studying AED combination therapy in the context of spontaneously occurring posttraumatic seizures. Despite the failure to achieve additivity from levetiracetam and gabapentin combination, it is important to recognize the objectivity of the isobolographic approach in the evaluation of AED combination therapy against seizures directly associated with brain injuries.

Comparison of gabapentin versus topiramate on clinically affected dogs with Chiari-like malformation and syringomyelia

To date there is no evidence-based data for efficacious treatment of neuropathic pain in dogs with Chiari-like malformation (CM) and syringomyelia (SM). The objective of this prospective cross-over study was...

Worsening of Myasthenia Gravis following the Addition of Gabapentin for Essential Tremor

Objective: To report a case of worsening myasthenia gravis after the initiation of gabapentin for treatment of essential tremor. Case Summary: A 69-year-old man experienced minor ptosis of the left eyelid, slight neck weakness, and transient difficulties in chewing food on day 6 of a slow gabapentin dosage titration. As the titration continued, the myasthenia symptoms progressed to bilateral ptosis, and there was dramatic worsening of weakness by day 23. He was taking gabapentin 1500 mg daily at the time; the drug was then tapered to discontinuation. All myasthenia gravis symptoms were reported as resolved 3 days after discontinuation of gabapentin. The initiation and discontinuation of gabapentin also coincided with improvement, then worsening of the patient's tremor. Discussion: Three published case reports describe worsening of myasthenia gravis during use of gabapentin for the treatment of various neuropathies. To the best of our knowledge, this is the first case report of a patient experiencing worsening of myasthenia gravis upon initiation of gabapentin for essential tremor. The Naranjo probability scale suggests a probable association between gabapentin and worsening of myasthenia gravis symptoms in our patient. Several myasthenia-like symptoms are listed in the gabapentin mongraph as low-frequency adverse events, increasing the possibility that gabapentin may have been unmasking or worsening myasthenia gravis in clinical trials. However, myasthenia gravis is not identified as a contraindication or caution for gabapentin use. Conclusions: Gabapentin should be used with caution in patients with myasthenia gravis, and clinicians must be aware of the potential risks of this therapy.

Multimodal analgesia with gabapentin, ketamine and dexamethasone in combination with paracetamol and ketorolac after hip arthroplasty: a preliminary study

It has been hypothesized that combinations of analgesics with different mechanisms of action may reduce or even prevent postoperative pain. We, therefore, investigated the analgesic effect of gabapentin, dexamethasone and low-dose ketamine in combination with paracetamol and ketorolac as compared with paracetamol and ketorolac alone after hip arthroplasty. In this double-blind study, 42 patients were randomly assigned to either a combination group [gabapentin 1200 mg+dexamethasone 8 mg+ketamine (0.15 mg kg(-1))+paracetamol 1 g+ketorolac 15 mg] or a control group (placebo+paracetamol 1 g+ketorolac 15 mg). The medication was given preoperatively except for ketorolac, which was given at the end of surgery. Postoperative pain treatment was paracetamol 1 gx3; ketorolac 15 mgx3; and patient-controlled intravenous morphine. Morphine consumption, pain intensity at rest and during mobilization, nausea and vomiting, sedation, dizziness, hallucination and consumption of ondansetron were recorded 2, 4 and 24 h after operation. A P value of less than 0.05 was considered statistically significant. Morphine consumption was not significantly different between groups (P=0.085). Overall pain scores were improved in the combination group as compared with the control group both at rest (P=0.042) and during mobilization (P=0.027). In the combination group, individual pain score above 30 mm on a 100 mm visual analogue scale was almost eliminated. The incidence of side effects did not differ between the groups. Preoperative gabapentin, dexamethasone and ketamine combined with paracetamol and ketorolac reduced overall pain scores in patients after hip arthroplasty as compared with paracetamol and ketorolac alone. Morphine consumption was not reduced.

VEP indices of cortical lateral interactions in epilepsy treatment

We extend Spekreijse’s strategy for analyzing lateral interactions in visual evoked potentials (VEPs) to clinical neurophysiologic testing of patients with epilepsy. Stimuli consisted of the radial windmill/dartboard pattern [Ratliff, F., & Zemon, V. (1982). Some new methods for the analysis of lateral interactions that influence the visual evoked potential. In: Bodis-Wollner (Ed.), Evoked potentials, Vol. 388. (pp. 113–124). New York: Annals of the New York Academy of Sciences.] and conventional checkerboards. The fundamental and 2nd-harmonic components of the steady-state responses were used to calculate indices reflecting facilitatory (FI) and suppressive (SI) cortical interactions. We carried out two studies. In the first, VEPs in 38 patients receiving antiepileptic drug (AED) therapy were compared to those of age-matched controls. For three AEDs (tiagabine, topiramate, and felbamate), addition of the drug did not change the FI and SI compared to baseline values or those of normal controls. However, the addition of gabapentin was associated with an increase of the FI, and this change was reversed when the medication was withdrawn. This suggested a medication-specific change in cortical lateral interactions. The second study focused on the effects of neurostimulation therapy. Eleven epilepsy patients receiving chronic vagus nerve stimulation (VNS) treatment were tested. By comparing VEPs recorded with the stimulator on (Stim-ON) and turned off (Stim-OFF) in the same session, we determined that VNS did not have a short-acting effect on lateral interactions. However, when compared with normal controls, the VNS patients had a significantly smaller SI ( p < .05), but no difference in the FI, demonstrating the presence of a chronic effect. We conclude that with the appropriate stimuli, VEPs can be used as a measure of cortical lateral interactions in normals and epileptic patients, and demonstrate specific changes in these interactions associated with certain treatment modalities.

Does addition of gabapentin to antidepressant therapy improve control of hot flashes?

Does addition of gabapentin to antidepressant therapy improve control of hot flashes?

Treatment with gabapentin of 11 dogs with refractory idiopathic epilepsy

Eleven dogs diagnosed with refractory idiopathic epilepsy were treated orally with gabapentin for a minimum of three months at an initial dose of 10 mg/kg every eight hours. They were...

Addition of gabapentin (G) to a modified FOLFOX regimen does not reduce neurotoxicity in patients (pts) with advanced colorectal cancer (CRC)

3581 Background: In order to determine the neuroprotectant effect of G against oxaliplatin-induced neurotoxicity, we sequentially recruited pt cohorts in a non-randomised phase II trial to FOLFOX then FOLFOX+G. Inclusion criteria were: advanced CRC; chemonaive except adjuvant completed ≥ 6 mths; measurable disease; PS 0–2. Pts received on D1 oxaliplatin 100mg/m2 IV over 2 hrs, LV 20mg/m2 bolus, 5-FU 400mg/m2 bolus then 5FU 2.4g/m2 46-hour infusion. Cycles were 2-wkly until PD or unacceptable toxicity. In addition, G cohort pts received G 300mg/d po, increased as required by 300mg/d increments (max 1800mg). Over 2 yrs, 40 pts were recruited to FOLFOX then 41 to FOLFOX+G. Minimum f/up was 18 mths. All but one pt received at least one dose of oxaliplatin and were evaluable for toxicity and treatment delivery. Pt characteristics were well balanced between cohorts. Maximum doses of G were 300mg/d in 10 pts, 600mg/d in 15, 900mg/d in 4, 1200mg/d in 9, and 1800mg/d in 3 pts. Treatment delivery for FOLFOX and FOLFOX+G cohorts respectively: median cycles 10 (1–13) vs 9 (1–12); oxaliplatin dose reduction >10% in 55% vs 50% of pts; cycles delayed >2days 19% vs 14%; treatment cessation due to toxicity 36% vs 37% (NS). RDI for FOLFOX and FOLFOX+G was oxaliplatin 82% vs 87%; 5FU bolus 52% vs 69%; 5FU infusion 82% vs 87% (NS). Responses (CR+PR) were seen in 48% of pts in each cohort. There were no significant difference in non-neurological toxicity.There was no significant difference in severity of neurotoxicity. For pts with grade 2/3 neurotoxicity, median time to recovery to grade 0/1 was 3.3mths for FOLFOX and 0.5mths for FOLFOX+G, however persistence of grade 2/3 neurotoxicity at 1 yr was 0% vs 17% respectively (NS). Conclusions: Addition of G to FOLFOX does not improve ability to deliver protocol-specified treatment and does not significantly reduce either severity or duration of neurotoxicity. This trial was sponsored by Sanofi-Synthelabo. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Sanofi Sanofi Sanofi Sanofi

Poster 107: Gabapentin’s effect on functional outcome after epidural spinal injections for lumbar radiculopathy.

Objective: To determine whether the addition of gabapentin can influence functional outcome in patients undergoing lumbar spinal injections for chronic pain. Design: Retrospective study of functional outcome in patients undergoing lumbar epidural spinal injections (ESIs) with and without the addition of gabapentin. Setting: Clinic. Participants: Subjects with chronic low back and radicular pain in the lower extremity were evaluated for functional improvement after ESI. The addition of gabapentin use was factored into the assessment. Interventions: Fluoroscopic guidance of ESI done at the clinically suspected level in the lumbar region. Main Outcome Measures: Oswestry Disability Index (ODI) and verbal rating scale (VRS) for current pain severity. Results: 75 patients with a radiculopathy were evaluated for an ESI. 29 were on gabapentin and 46 were not. The mean gabapentin use ± SD prior to injections was 1662±950mg. The patients were followed postinjection on average for 10.8±3.9 weeks. Posttreatment ODI score (61.9±16.2) was significantly improved ( P<.001) in all cases compared with pretreatment ODI score (66.8±17.3). Pretreatment ODI and VRS scores did not differ significantly between groups showing positive (66.2±17.7, 7.2±1.9) and negative (67.1±17.2, 7.8±1.0) gabapentin use ( P<.05). ODI improvement and VRS postinjection did not differ significantly for positive gabapentin use (6.6±10.8, 6.2±1.6) compared with negative use (3.7±15.3, 6.2±1.4) ( P<.05). Conclusions: Subjects undergoing ESI for chronic radicular pain, who were using gabapentin prior to injection, did not show significant improvement in functional outcome as measured by the ODI or in current pain intensity as measured by the VRS. This study did not demonstrate that gabapentin use prior to spinal procedures has any benefit on the outcome of spinal injections in patients with chronic pain. The limitation of the study was the lack of patients on gabapentin and low functional improvement after ESI. The timing of gabapentin use and the dose of maximal therapeutic benefit were not evaluated by this study.

Metabolic approach of absence seizures in a genetic model of absence epilepsy, the GAERS: study of the leucine-glutamate cycle.

We suggest that a dysregulation of energy metabolism in the brain of genetic absence epilepsy rats from Strasbourg (GAERS) could create a specific cerebral environment that would favor the expression of spike-and-wave discharges (SWD) in the thalamocortical loop, largely dependent on glutamatergic and gamma-aminobutyric acid (GABA)-ergic neurotransmissions. We tested several aspects of metabolic activity in the brain of GAERS compared to a genetic strain of nonepileptic (NE) rats. Glucose metabolism was higher in all brain regions of GAERS compared to those of NE rats along the whole glycolytic and aerobic pathways, as assessed by regional histochemical measurement of lactate dehydrogenase and cytochrome oxidase activities. Branched-chain amino acids (BCAA) and alpha-ketoisocaproate (alpha-KIC), the ketoacid of leucine, when injected intraperitoneally, increased the number of SWD in GAERS but had only a slight effect on their duration. These data speak in favor of a BCAA- or alpha-KIC-induced change in neuronal excitability. Leucine and alpha-KIC decreased the concentration of glutamate in thalamus and cortex without affecting GABA concentrations. Thus, BCAA and alpha-KIC, by decreasing glutamatergic neurotransmission, could favor GABAergic neurotransmission, which is known to increase the occurrence of seizures in GAERS. Finally, the transport of [1-(14)C]alpha-KIC in freshly isolated cortical neurons was lower in GAERS than in NE rats, and this difference was shown to be of metabolic origin. The addition of gabapentin, a specific inhibitor of BCAA transaminase (BCAT), reduced the transport of [1-(14)C]alpha-KIC in GAERS and NE rats to a level that became identical in both strains. This strain-dependent change was not related to a difference in the activity of BCAT, which was identical in GAERS and NE rats. The exact origin of this apparent metabolic dysregulation of energy metabolism in GAERS that could underlie the origin of seizures in that strain remains to be explored further.

Interstitial Cystitis and the Potential Role of Gabapentin

Gabapentin, an antiepileptic agent, is a safe and versatile medication also used in the adjunctive treatment of painful disorders. These include neuropathic pain, such as postherpetic neuralgia, diabetic neuropathy, and the pain of reflex sympathetic dystrophy. Interstitial cystitis, a painful disease entity, shares many common features of these chronic pain states, and the use of gabapentin can assist in pain control. Gabapentin, as an adjunctive agent, may reduce use of cotherapeutics such as narcotics. Two patients with interstitial cystitis improved functional capacity within their activities of daily living and received adequate pain control with the addition of gabapentin to their medication regimen.

Increased seizure frequency associated with felbamate withdrawal in adults.

To characterize changes in seizure frequency following felbamate withdrawal. Nonrandomized, retrospective chart review of a case series. Epilepsy program specializing in adults with uncontrolled epilepsy. Forty-five ambulatory patients withdrawn from felbamate use. Patients were included if they had received felbamate for at least 1 month, were 18 years or older, had accurate seizure frequency documentation, had accurate documentation of all antiepileptic drugs, and received the same concomitant antiepileptic drugs before and after felbamate therapy, except for the possible addition of gabapentin. Patients were excluded if they had hematologic or hepatic toxic effects with felbamate, were unable to withdraw from felbamate treatment, had a progressive neurologic disorder, or participated in another drug trial. When information became available on aplastic anemia and hepatotoxicity associated with felbamate, all patients were advised to taper their felbamate dosage over approximately 2 weeks. They received written instructions for tapering felbamate and adjusting concomitant antiepileptic drugs and kept calendars to note the number of seizures. The charts of all patients who received felbamate were evaluated for adherence to inclusion and exclusion criteria. Statistical analysis was performed using a log-linear model for count data. Seizure frequency during the 6 months before initiating felbamate therapy served as the baseline. Changes in seizure frequency were evaluated by comparing the number of seizures in the month felbamate was tapered and the 3 months after felbamate discontinuation with the baseline frequency. Comparisons were made between patients who started gabapentin therapy and those who did not and between felbamate responders and nonresponders. Felbamate withdrawal resulted in a significant (P=.02) increase in seizure frequency. Patients receiving gabapentin had a smaller increase in seizure frequency, but the difference was not statistically significant. There was no statistically significant difference in seizure frequency between felbamate responders and nonresponders. Felbamate withdrawal caused a significant increase in seizure frequency over the subsequent 3 months. These findings are important for clinical trial design and clinical practice.

Gabapentin Adjunctive Therapy in Neuropathic Pain States

This is a report of a trial of the new antiepileptic agent gabapentin in patients with intractable neuropathic pain. A case series of patients with a diagnosis of neuropathic pain whose previous management was inadequate were given oral gabapentin in increasing doses and were followed for a minimum of 2 months, monitored for efficacy and side effects. An outpatient pain management center located within a major university medical center. Convenience sample of patients referred for management of intractable neuropathic pain. Simplification of existing pharmacologic management, addition of gabapentin, and attempted reduction of opiate analgesic doses. Patient self-reports and pain scores in successive office visits. Gabapentin provides analgesic activity for patients with neuropathic pain and has the advantage of a low side effect profile and drug toxicity.