Review of toxicity and trends in the use of tiagabine as reported to US poison centers from 2000 to 2012.

BACKGROUND: Tiagabine is a novel antiepileptic that acts by increasing synaptic and extracellular gamma-aminobutyric acid concentrations. Information concerning overdose of tiagabine is limited. After introduction, an increasing number of off-label uses suggested that tiagabine use would increase. However in 2005 and 2008, warnings from the Food and Drug Administration (FDA) were issued on the risk of seizures in non-epileptic and increased suicide ideation. We evaluated the temporal trends associated with these two warnings as well as clinical outcomes from tiagabine overdose. METHOD: A retrospective review of all single substance tiagabine exposures in National Poison Data System (NPDS) from 2000 to 2012. RESULTS: A total of 2147 patients had ingested tiagabine, with a mean of 165 year(-1). This was disproportionally distributed, with a steep rise leading up to 2004 (max 559 year(-1)) and then a significant decline (p < 0.05) between 2005 and 2006. The number of cases reported to NPDS mirrored the sales of tiagabine. Clinical effects were predominantly neurological, with the most commonly reported effects being drowsiness (27%), agitation (19%), confusion (12%), seizures (11%), and tachycardia (10%). In all, 758 patients (35%) showed a major or moderate medical outcome, with no deaths reported. A disproportionate share of the major outcomes was in the suicide attempt group (73%). The majority of patients (75%) were treated in a health-care facility (HCF). CONCLUSIONS: The HCF usage is likely due to high rate of symptomatic patients (59%) and the large proportion of suicide attempt cases. The frequency of tiagabine cases in NPDS mirrored pharmaceutical sales, with steep declines temporally related to the 2005 FDA warning.

Deliberate self-poisoning with tiagabine: an unusual toxidrome.

Tiagabine is an anticonvulsant acting by selective inhibition of neuronal and glial gamma-aminobutyric acid uptake, resulting in increased gamma-aminobutyric acid-mediated inhibition in the brain. Few reports in the literature describe the clinical course of severe tiagabine intoxication. A 44-year-old woman presented after deliberate self-poisoning with 100 tiagabine 15 mg tablets (1,500 mg; 25 mg/kg). Serum tiagabine level was 4,600 microg/L (1,725 mmol/L) at presentation, 20 times levels associated with therapeutic dosing. Intoxication was manifested by profuse vomiting, coma, myoclonus, generalized rigidity, bradycardia, hypertension, hypersalivation and generalized piloerection within 2 h of ingestion. The patient was intubated and management was supportive. Coma lasted until 10 h post-ingestion, but recovery was complicated by severe agitated delirium lasting 12 h. The patient recovered fully within 26 h of ingestion. Tiagabine deliberate self-poisoning was associated with the rapid onset of coma and an unusual toxidrome. Recovery, although complicated by agitated delirium, was complete within 26 h.

[Tiagabine overdose--report of two cases]. / Ostre zatrucia tiagabina--opis dwóch przypadków.

UNLABELLED: Tiagabine is a derivative of nipecotinic acid used in the therapy of partial seizures, partial seizures with secondary generalization, stress disorder, psychosis and cocaine dependence. The pharmacologic effect of the drug is achieved by inhibition of reuptake of gamma aminobutyric acid (GABA) into glial cells and neurons, without permanent increase in whole brain GABA concentration. Symptoms of acute tiagabine overdose include seizures, coma, respiratory depression ' and less often dystonias, involuntary movements, somnolence, agitation, tachycardia and increase or decrease of blood pressure. Two cases of acute tiagabine overdose have been described in the paper presenting with partial and generalized seizures which were managed with benzodiazepines. CONCLUSIONS: The onset of symptoms of acute tiagabine overdose is rapid with resolution within first 24 hours from exposure. Acute tiagabine poisoning may present with a wide variety of neurological symptoms. Administration of benzodiazepines may improve the outcome of overdose.

Seizures in a pediatric patient with a tiagabine overdose.

INTRODUCTION: Tiagabine (TGB) is a novel antiepileptic that decreases GABA uptake. The literature contains one report of an adult with epilepsy who ingested up to 1 gram of TGB and developed status epilepticus. We reported on a pediatric patient who ingested significantly less TGB but still developed tonic-clonic seizures. CASE REPORT: A previously healthy, 13 kg, two-year-old girl developed generalized tonic-clonic seizure activity at home approximately 1 hour after ingesting 90 mg of her grandmother's TGB (forty five 2 mg tablets). At the hospital she had two 5 minute seizures at 1.5 and 3.5 hours post ingestion. Her serum TGB levels were 530 and 130 ng/ml approximately 5 and 11 hours post-ingestion (5-70 ng/ml trough levels with most probable range for seizure control). She was discharged 27 hours post ingestion, and she was in good condition. CONCLUSION: An overdose of TGB, a novel anti-epileptic, can cause convulsive seizures.

Retrospective evaluation of tiagabine overdose.

BACKGROUND: Tiagabine is an anticonvulsant that blocks reuptake of the inhibitory neurotransmitter GABA. There are no published studies or case series of tiagabine overdoses. METHODS: The records of six poison centers and one statewide poison center network were searched for all exposures to tiagabine for the years 2000-2002. Inclusion criterion was a human tiagabine exposure with follow-up to a known outcome; exclusion criterion was multiple drug ingestion. RESULTS: 57 cases met the inclusion criterion. Thirty-seven patients were female (67%). Mean and median ages were 30.5 years (S.D. +/- 18.5) and 31 years, respectively, with a range of 2 to 80 years. Seven patients were < or = 6 years. Neurologic symptoms were common: lethargy, seizures (multiple), status epilepticus, seizure (single), coma, confusion, agitation, tremors, dizziness, dystonias/abnormal posturing, and hallucinations. Other symptoms included respiratory depression, tachycardia, hypertension, and hypotension. Therapies included benzodiazepines, mechanical ventilation, phenytoin, phenobarbital, diphenhydramine, and dopamine. The mean onset and duration of symptoms were 1.3 hours (+/- 0.5, range 1-2 hours) and 9.1 hours (+/- 3.8, range 4-24 hours), respectively. Dose ingested by history was known for 38 patients (67%). The lowest dose with the development of multiple seizures and coma was 96 mg. This occurred in a 36-year-old female with a history of epilepsy. The lowest dose with symptoms in a child was 8 mg, in a 6-year-old with drowsiness. Mean dose of those with and without symptoms was 102 mg and 10 mg, respectively. The mean dose for patients experiencing seizures was 224 mg (+/- 172, range 96 to 680 mg). The mean dose for patients experiencing coma and respiratory depression was 270 mg (+/- 204, range 96 to 680 mg). Fifty-two patients (91%) were evaluated in the ED of whom 43 were admitted for medical care. CONCLUSION: Seizures and altered mental status were common with tiagabine overdose, with rapid onset and resolution of symptoms. In this series, seizures did not occur until the ingestion was greater than three times the maximum recommended daily dose.

Tiagabine overdose: a case of status epilepticus in a non-epileptic patient.

Tiagabine is an antiepileptic drug used as adjunctive therapy for partial seizures that is believed to selectively inhibit the presynaptic reuptake of gamma aminobutyric acid (GABA). We describe a case of a tiagabine overdose that resulted in status epilepticus (SE) in a patient with no seizure history. A 14-year-old girl with a history of asthma presented with convulsive SE after ingestion of an unknown amount of her sister's tiagabine in a suicide attempt. Attempted anticonvulsant therapy included a total of diazepam 10 mg IV, lorazepam 6 mg IV, pyridoxine 5 g IV, and fosphenytoin 20 mg PE/kg. All were without effect. A computed tomography and electrocardiogram were normal. Continuous bedside EEG monitoring showed suppression of seizure activity following intravenous midazolam. A tiagabine level obtained on ED arrival was 420 ng/mL (therapeutic 20-103 ng/mL). The patient was discharged to psychiatry within 1 week with no neurologic sequelae.

Intentional overdose with tiagabine: an unusual clinical presentation.

Tiagabine (Gabitril) is a unique anticonvulsant that is prescribed for a variety of psychiatric disorders. We report a case of intentional self-poisoning with tiagabine. A 46-year-old woman was brought to the Emergency Department after being found confused and nonverbal while wandering in a field. Eighteen tablets (72 mg) of her tiagabine prescription were missing. Remarkable findings on initial examination were facial grimacing, flexure posturing of both upper extremities, and 7-mm, reactive pupils. She was uncommunicative and unable to follow commands. Vital signs, blood chemistries and a head CT scan were normal. Urine toxicology screening was negative. An extrapyramidal reaction was suspected and diphenhydramine 50 mg was administered without effect. Lorazepam 2 mg was given with significant improvement. She was admitted for observation and all symptoms resolved within 12 h of admission. Tiagabine overdose causes an unusual array of neurological symptoms, many similar to reported adverse effects during therapeutic use.

Deliberate overdose with the novel anticonvulsant tiagabine.

Tiagabine is a novel antiepileptic drug which acts by decreasing gamma aminobutyric acid uptake in astrocytes and neurones. Here the first case of deliberate overdose with this compound in a patient on concomitant phenytoin is reported. On admission to hospital his conscious level deteriorated to grade III coma. No changes in the electrocardiogram were noted. Recovery from the initial effects was rapid, and there were no sequelae. Plasma levels of tiagabine (3.1 micrograms/ml) 4 hours after ingestion were 30 times higher than at typical steady state during therapeutic dosing. The effects of poisoning with current first-line antiepileptic drugs are reviewed. The newer agents, particularly those with greater biochemical specificity, may be safer in overdose than the more established anticonvulsants.