Gabapentin-induced coma in a patient with renal failure

Extracorporeal Treatment for Gabapentin and Pregabalin Poisoning: Systematic Review and Recommendations From the EXTRIP Workgroup

Toxicity from gabapentin and pregabalin overdose is commonly encountered. Treatment is supportive, and the use of extracorporeal treatments (ECTRs) is controversial. The EXTRIP workgroup conducted systematic reviews of the literature and summarized findings following published methods. Thirty-three articles (30 patient reports and 3 pharmacokinetic studies) met the inclusion criteria. High gabapentinoid extracorporeal clearance (>150mL/min) and short elimination half-life (<5 hours) were reported with hemodialysis. The workgroup assessed gabapentin and pregabalin as "dialyzable" for patients with decreased kidney function (quality of the evidence grade as A and B, respectively). Limited clinical data were available (24 patients with gabapentin toxicity and 7 with pregabalin toxicity received ECTR). Severe toxicity, mortality, and sequelae were rare in cases receiving ECTR and in historical controls receiving standard care alone. No clear clinical benefit from ECTR could be identified although major knowledge gaps were acknowledged, as well as costs and harms of ECTR. The EXTRIP workgroup suggests against performing ECTR in addition to standard care rather than standard care alone (weak recommendation, very low quality of evidence) for gabapentinoid poisoning in patients with normal kidney function. If decreased kidney function and coma requiring mechanical ventilation are present, the workgroup suggests performing ECTR in addition to standard care (weak recommendation, very low quality of evidence).

Flumazenil therapy for a gabapentin-induced coma: a case report

Background

Spasticity and neuropathic pain are common in patients after spinal cord injury and negatively affect patients’ quality of life. Gabapentin and baclofen are frequently used to treat these conditions. We present a flumazenil-reversed gabapentin-induced coma case, which, to our knowledge, is the second one described in scientific literature.

Case presentation

A 70-year-old Caucasian man was admitted to our neurorehabilitation ward following a fall with cervical trauma that resulted in immediate tetraplegia. During his stay, he suffered from lower limb pain, both neuropathic and due to severe spasticity. Gradual baclofen and gabapentin administration was prescribed, with reduction in both pain and spasticity. One morning, the patient was found unresponsive, with a Glasgow Coma Score of 3. Head computerized tomography, electrocardiogram, electroencephalogram, vital signs, blood tests, breathing, and blood oxygenation were normal. Renal and liver failure were ruled out. Intravenous 0.25 mg of flumazenil (Anexate) was administered, resulting in complete neurocognitive recovery with a Glasgow Coma Score of 15.

Discussion and conclusions

This case report highlights the importance of the individual response to certain pharmacological agents and suggests that further studies need to be conducted both on flumazenil and gabapentin pharmacodynamics to better understand their molecular–receptor activity, and on possible multiple flumazenil mechanisms of action, beyond its classical strict benzodiazepine antagonist action.

Managing the patient with epilepsy and renal impairment

PURPOSE

Epilepsy affects more than 50 million people worldwide and its management can be complicated by comorbidities such as impaired renal function. To optimize epilepsy control in patients with kidney disease, clinicians need to be aware of how antiepileptic drugs (AEDs) are affected by impaired renal function and how the kidneys are affected by epilepsy management strategies. Herein we present a narrative review with systematic literature search to discuss the use of AEDs in patients with renal impairment, including those undergoing dialysis, as well as the nephrotoxic effects of some AEDs. We finally conclude the article by providing practical tips about our approach to using AEDs in the setting of renal disease.

METHODS

A literature search targeting epilepsy management in patients with kidney disease was performed in MEDLINE database (1946 to 7th Jan 2019).

RESULTS

A total of 1193 articles were found. After duplicate removal, title and abstract screening followed by full text screening, a total of 110 references were included in this review. Additional information was included from drug product monographs.

CONCLUSION

The disposition of AEDs can be altered in patients with impaired renal function, leading to a higher risk of AED toxicity or therapy failure. Renal dosage adjustment and close monitoring is recommended. Although AED-induced nephrotoxicity is rare, it is unpredictable and clinicians need to vigilant about this possibility. In addition, AEDs renal adverse reactions and renal drug interactions should be considered when selecting an AED.

Gabapentin dose and the 30-day risk of altered mental status in older adults: A retrospective population-based study

Gabapentin is an effective treatment for chronic neuropathic pain but may cause dizziness, drowsiness, and confusion in some older adults. The goal of this study was to assess the association between gabapentin dosing and adverse outcomes by obtaining estimates of the 30-day risk of hospitalization with altered mental status and mortality in older adults (mean age 76 years) in Ontario, Canada initiated on high dose (>600 mg/day; n = 34,159) compared to low dose (≤600 mg/day; n = 76,025) oral gabapentin in routine outpatient care. A population-based, retrospective cohort study assessing new gabapentin use between 2002 to 2014 was conducted. The primary outcome was 30-day hospitalization with an urgent head computed tomography (CT) scan in the absence of evidence of stroke (a proxy for altered mental status). The secondary outcome was 30-day all-cause mortality. The baseline characteristics measured in the two dose groups were similar. Initiation of a high versus low dose of gabapentin was associated with a higher risk of hospitalization with head CT scan (1.27% vs. 1.06%, absolute risk difference 0.21%, adjusted relative risk 1.29 [95% CI 1.14 to 1.46], number needed to treat 477) but not a statistically significant higher risk of mortality (1.25% vs. 1.16%, absolute risk difference of 0.09%, adjusted relative risk of 1.01 [95% CI 0.89 to 1.14]). Overall, the risk of being hospitalized with altered mental status after initiating gabapentin remains low, but may be reduced through the judicious use of gabapentin, use of the lowest dose to control pain, and vigilance for early signs of altered mental status.

Postoperative pain management in patients with chronic kidney disease

Chronic kidney disease (CKD) is a health care problem with increasing prevalence worldwide. Pain management represents one of the challenges in providing perioperative care for this group of patients. Physicians from different specialties may be involved in pain management of CKD patients, especially in advanced stages. It is important to understand the clinical staging of kidney function in CKD patients as the pharmacotherapeutic pain management strategies change as kidney function becomes progressively impaired. Special emphasis should be placed on dose adjustment of certain analgesics as well as prevention of further deterioration of renal function that could be induced by certain classes of analgesics. Chronic pain is a common finding in CKD patients which may be caused by the primary disease that led to kidney damage or can be a direct result of CKD and hemodialysis. The presence of chronic pain in some of the CKD patients makes postoperative pain management in these patients more challenging. This review focuses on the plans and challenges of postoperative pain management for patient at different stages of CKD undergoing surgical intervention to provide optimum pain control for this patient population. Further clinical studies are required to address the optimal medication regimen for postoperative pain management in the different stages of CKD.

Effects of NB001 and gabapentin on irritable bowel syndrome-induced behavioral anxiety and spontaneous pain

Irritable bowel syndrome (IBS) is characterized by recurrent abdominal discomfort, spontaneous pain, colorectal hypersensitivity and bowel dysfunction. Patients with IBS also suffer from emotional anxiety and depression. However, few animal studies have investigated IBS-induced spontaneous pain and behavioral anxiety. In this study, we assessed spontaneous pain and anxiety behaviors in an adult mouse model of IBS induced by zymosan administration. By using Fos protein as a marker, we found that sensory and emotion related brain regions were activated at day 7 after the treatment with zymosan; these regions include the prefrontal cortex, anterior cingulate cortex, insular cortex and amygdala. Behaviorally, zymosan administration triggered spontaneous pain (decreased spontaneous activities in the open field test) and increased anxiety-like behaviors in three different tests (the open field, elevated plus maze and light/dark box tests). Intraperitoneal injection of NB001, an adenylyl cyclase 1 (AC1) inhibitor, reduced spontaneous pain but had no significant effect on behavioral anxiety. In contrast, gabapentin reduced both spontaneous pain and behavioral anxiety. These results indicate that NB001 and gabapentin may inhibit spontaneous pain and anxiety-like behaviors through different mechanisms.

Treatment of gabapentin-induced myoclonus with continuous renal replacement therapy

A 56-year-old man with diabetes, hypertension, and chronic kidney disease presented to the emergency room with a complaint of pain in his right foot. He was found to have tremors. Gabapentin toxicity was suspected and the patient was found to have high gabapentin level (6.3 mcg/ml). Patient was commenced on continuous venovenous hemodiafiltration (CVVHD) and the pharmacokinetics of gabapentin was studied. The patient improved symptomatically and his tremors subsided. In this case report, we describe the successful management of gabapentin toxicity with continuous renal replacement therapy and calculate the clearance of gabapentin which will enable future treatment of gabapentin toxicity by CVVHD.

Non-estrogen conventional and phytochemical treatments for vasomotor symptoms: what needs to be known for practice

OBJECTIVE

Non-hormonal treatment for menopausal vasomotor symptoms (VMS) is needed in women in whom there are medical or personal concerns on the use of hormone therapy. This paper reviews conventional and phytochemical therapies available for the relief of VMS, on their mechanisms of action, their efficacy and safety concerns.

METHODS

Medline was searched through Pubmed on the names of the diverse therapies analyzed, up to June 2011. The Cochrane Controlled Clinical Trials Register Database was searched for relevant trials that provided data on treatment of menopausal hot flushes.

RESULTS

All non-estrogen treatments for VMS are less efficacious than estrogen treatment. Randomized trials with neuroendocrine agents show globally modest to moderate reduction of VMS and frequent bothersome adverse events. The variability of effects makes it possible to undergo treatment in search for individual response where estrogen treatment is contraindicated. The antidepressants that interact with cytochrome P450, inhibiting tamoxifen metabolism to endoxifen, interfere with tamoxifen therapy in breast cancer patients. Otherwise, botanical products containing isoflavones from soy bean or red clover have great variability in bioavailability, have a broader spectrum of action than estradiol, and have predominant estrogen receptor-b activity. The efficacy of phytoestrogens on VMS is similar to placebo. They should be avoided in women with breast cancer and, in particular, in women being treated with tamoxifen or aromatase inhibitors due to possible antagonism. Cimicifuga racemosa is not a phytoestrogen, has partial serotonin agonist action and has a modest effect on VMS.

CONCLUSIONS

There are safe non-hormonal conventional treatments for menopausal VMS, although they are less efficacious than estrogens. The indication of phytochemicals is for women who make this choice on personal beliefs; long-term studies of larger groups of patients are needed to assess safety.

Suicide by gabapentin overdose

Gabapentin is an antiepileptic drug that is prescribed for both FDA-approved and multiple off-label conditions, and has a relatively safe side-effect profile. Rare cases of overdose-related adverse effects have been reported in the literature. Described herein are the circumstances and autopsy findings of a 62-year-old woman with a history of depression, whose death was caused by intentional ingestion of excess gabapentin. The postmortem peripheral blood gabapentin concentration as determined by high-performance liquid chromatography/tandem mass spectroscopy was 88 μg/mL. Previously reported cases of individuals surviving gabapentin overdoses are discussed and compared with this case. Based on a review of the available literature, this appears to be the first published report of a death due solely to gabapentin toxicity.

Gabapentin toxicity in patients with chronic kidney disease: a preventable cause of morbidity

BACKGROUND

Gabapentin is frequently used as an analgesic in patients with chronic kidney disease. Although gabapentin is well known for its favorable pharmacokinetics, it is exclusively eliminated renally, and patients with chronic kidney disease are at risk for toxicity. Existing literature on such risk is lacking.

METHODS

We examined the Mayo Clinic Rochester database from 1998 to 2007 in patients with serum gabapentin measurements and known medical outcomes. A total of 729 patients were stratified according to their estimated glomerular filtration rate: group I, 126 individuals with estimated glomerular filtration greater than 90 mL/min/1.72 mm(2) [corrected] ; group II, 594 individuals with estimated glomerular filtration less than 90 mL/min/1.72 mm(2) [corrected] without dialysis; group III, 9 individuals with chronic dialysis.

RESULTS

Patients in groups II and III had higher serum gabapentin levels (8.39+/-0.32 microL/mL and 58.8+/-10.22 microL/mL, respectively) than in group I (5.52+/-0.32 microL/mL, P<.01). Toxicity occurred exclusively in groups II (5.56%) and III (77.8%); toxic manifestations were more severe in group III than in group II. Elderly individuals with multiple comorbidities were overrepresented in those with toxic manifestations. Gabapentin toxicity was suspected initially in only 41.5% of symptomatic cases.

CONCLUSION

Gabapentin toxicity in patients with chronic kidney disease is underrecognized. Patients with chronic kidney disease often receive inappropriately high gabapentin dosage for their kidney function, occasioning overt toxicity; advanced age and comorbidity predispose these patients for toxicity. Heightened awareness of such preventable risk, amid the chronic kidney disease epidemic, would be cost-effective and improve healthcare quality.

A probable case of gabapentin-related reversible hearing loss in a patient with acute renal failure

BACKGROUND

As described in the literature, gabapentin toxicity in patients with impaired renal function can manifest as coma, myoclonus, tremulousness, or altered mental status. Gabapentin is an antiepileptic agent indicated for use as an adjunct therapy in partial seizures and postherpetic neuralgia but is also prescribed for the treatment of diabetic peripheral neuropathy.

CASE SUMMARY

A 46-year-old white woman (height, 167 cm; weight, 177 kg; body mass index, 62.8 kg/m2) with a 6-year history of diabetes mellitus and previously normal renal function, presented to the emergency department of Wake Forest University Baptist Medical Center with anuria (a serum creatinine level of 7.4 mg/dL), hearing loss, myoclonus, and confusion with hallucinations lasting for 3 days. Her blood pressure was 110/74 mm Hg. The patient's preadmit medication list included: lisinopril (40 mg QD), hydrochlorothiazide (25 mg QD), and furosemide (80 mg QD) for hypertension; atorvastatin (10 mg QD) for hyperlipidemia; omeprazole (20 mg QD) for gastroesophageal reflux disease; salmeterol/fluticasone inhaler (100/50 microg; 1 puff BID) and albuterol metered-dose inhaler (90 microg as needed) for asthma; metformin (500 mg BID) and insulin lispro per sliding scale for type 2 diabetes mellitus; oxycodone controlled release (60 mg TID) for chronic osteoarthritis and low back pain; alprazolam (0.5 mg every 8 hours as needed) for generalized anxiety disorder; venlafaxine (150 mg BID) for depression; and gabapentin (300 mg TID) for diabetic peripheral neuropathy. The patient's symptoms (hearing loss, myoclonus, and confusion) improved after 1 session of hemodialysis (approximately 10 hours following admission) and had resolved at the time of discharge (4 days later). On admission, the gabapentin concentration was 17.6 microg/mL, and following hemodialysis, the gabapentin concentration was undetectable (by discharge/day 4). The timing of the patient's last dose of gabapentin is unknown. Normal doses for the treatment of diabetic peripheral neuropathy range from 900 to 3600 mg/d divided 3 times daily.

CONCLUSIONS

We report a patient with acute renal failure who developed hearing loss, myoclonus, and confusion with hallucinations in the presence of elevated gabapentin concentrations. Due to rapid improvement after hemodialysis and discontinuation of gabapentin, we believe that these symptoms were probably due to gabapentin toxicity.

Gabapentin-induced rhabdomyolysis in a patient with diabetic neuropathy

Gabapentin (GBP) is a drug which is frequently used in diabetic neuropathy. Common adverse effects of GBP include drowsiness, dizziness, ataxia, somnolence, and fatigue. Rhabdomyolysis is an extremely rare side effect of GBP. In this report we describe a case of GBP-induced rhabdomyolysis in a 63-year-old diabetic woman. She presented with severe muscle pain in her extremities, fatigue, decreased urine output and urine discoloration within 3 weeks after starting treatment with GBP (900 mg/day) for diabetic neuropathy. Laboratory tests revealed extreme elevations of muscle enzymes, increased creatinine and potassium levels. She required hemodialysis as a result of anuria. Investigation confirmed the diagnosis of rhabdomyolysis, and discontinuation of GBP resulted in resolution of clinical and biochemical features of rhabdomyolysis.

Gabapentin toxicity in renal failure: the importance of dose adjustment

OBJECTIVE

This case report outlines a significant type of morbidity due to continued use of gabapentin during an episode of acute renal failure. Setting. University teaching hospital.

DISCUSSION

Gabapentin is widely used in the management of pain. It is entirely excreted through the renal system so this needs to be considered in any patient becoming acutely ill and developing renal failure. We describe a patient who developed significant deterioration in her conscious level due to iatrogenic gabapentin overdose.

CONCLUSION

All doctors need to be aware of the need to review the indications for gabapentin use during periods of acute illness, especially with regard to renal impairment. Off-label use should be discouraged.

Use of gabapentin in the treatment of behavioural and psychological symptoms of dementia: a review of the evidence

Behavioural and psychological symptoms of dementia (BPSD) have been defined as a heterogeneous range of psychological reactions, psychiatric symptoms and behaviours that may be unsafe, disruptive and impair the care of a patient in a given environment. To date, there are no US FDA-approved drugs or clear standards of pharmacological care for the treatment of BPSD. The novel antiepileptic agent gabapentin is being increasingly considered for use in the geriatric population because of its relatively favourable safety profile compared with other classes of psychiatric medications. Gabapentin has been administered to several geriatric patients with bipolar disorder and patients with dementia. It has also been reported to be successful in the treatment of a 13-year-old boy with behavioural dyscontrol, a finding that suggested a possible role for gabapentin in the treatment of other behavioural disorders. The purpose of this review was to find evidence for the use of gabapentin in the treatment of BPSD. To this end, a search was performed for case reports, case series, controlled trials and reviews of gabapentin in the treatment of this condition. The key words 'dementia', 'Alzheimer's disease' and 'gabapentin' were used. Searches were performed in PubMed, PsycINFO, Ovid MEDLINE, Cochrane Library and ClinicalTrials.gov. The search revealed that there are limited data on the efficacy of gabapentin for BPSD in the form of 11 case reports, 3 case series and 1 retrospective chart review; no controlled studies appear to have been published to date on this topic. In most of the reviewed cases, gabapentin was reported to be a well tolerated and effective treatment for BPSD. However, two case reports in which gabapentin was used in the context of agitation in dementia with Lewy bodies questioned the appropriateness of gabapentin for all types of dementia-related agitation. The dearth of available data limits support for the off-label use of gabapentin for the treatment of BPSD. Furthermore, controlled studies should be conducted before gabapentin can be clinically indicated for the successful treatment of BPSD.