Association of intravenous phenytoin toxicity with demographic, clinical, and dosing parameters

Intravenous fosphenytoin as treatment for acute exacerbation of trigeminal neuralgia: A prospective systematic study of 15 patients

INTRODUCTION

Intravenous fosphenytoin is widely used for acute exacerbation of trigeminal neuralgia, however, few studies have investigated this treatment. We aimed to examine the efficacy and side effects of initial intravenous fosphenytoin plus oral tapering of phenytoin for exacerbation of trigeminal neuralgia.

METHODS

Consecutive patients with primary trigeminal neuralgia were included in this prospective observational 90-days follow-up study. Data were collected using standardized interviews before, at 24 hours, day 7, 30 and 90 post loading dose. The primary outcome was the proportion of responders defined as a 50% reduction in pain intensity 24 hours post loading dose.

RESULTS

We included 15 patients. Nine patients (60%) were responders. Pain intensity 24 hours post loading dose was reduced by 5.00 points on the numerical rating scale (p < 0.001), and at day 7 by 5.5 points (p < 0.001). The most common side effects were hypotension and dizziness.

CONCLUSION

Intravenous fosphenytoin relieves trigeminal neuralgia pain in most patients and provides a window for titrating prophylactic trigeminal neuralgia medications or planning neurosurgery. The decision to administer intravenous fosphenytoin should be taken with support from trigeminal neuralgia experts and involves considerations of co-morbidities and other treatment options for acute exacerbation of trigeminal neuralgia.Clinical Trial: Preregistered (ClinicalTrials.gov Identifier: NCT03712254.

Acute Management of Hypertension Following Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is responsible for approximately 15% of strokes annually in the United States, with nearly 1 in 3 of these patients dying without ever leaving the hospital. Because this disproportionate mortality risk has been stagnant for nearly 3 decades, a main area of research has been focused on the optimal strategies to reduce mortality and improve functional outcomes. The acute hypertensive response following ICH has been shown to facilitate ICH expansion and is a strong predictor of mortality. Rapidly reducing blood pressure was once thought to induce cerebral ischemia, though has been found to be safe in certain patient populations. Clinicians must work quickly to determine whether specific patient populations may benefit from acute lowering of systolic blood pressure (SBP) following ICH. This review provides nurses with a summary of the available literature on blood pressure control following ICH. It focuses on intravenous and oral antihypertensive medications available in the United States that may be utilized to acutely lower SBP, as well as medications outside of the antihypertensive class used during the acute setting that may reduce SBP.

Cardiovascular adverse effects of phenytoin

Phenytoin is an established drug in the treatment of acute repetitive seizures and status epilepticus. One of its main advantages over benzodiazepines is the less sedative effect. However, the possibility of cardiovascular adverse effects with the intravenous use of phenytoin cause a reluctance to its usage, and this has lead to a search for safer anticonvulsant drugs. In this study, we aimed to review the studies which evaluated the safety of phenytoin with respect to cardiovascular adverse effects. The original clinical trials and case reports listed in PUBMED in English language between the years of 1946-2014 were evaluated. As the key words, "phenytoin, diphenylhydantoin, epilepsy, seizure, cardiac toxicity, asystole, arrhythmia, respiratory arrest, hypotension, death" were used. Thirty-two clinical trials and ten case reports were identified. In the case reports, a rapid infusion rate (>50 mg/min) of phenytoin appeared as the major cause of increased mortality. In contrast, no serious cardiovascular adverse effects leading to death were met in the clinical trials which applied the recommended infusion rate and dosages. An infusion rate of 50 mg/min was reported to be safe for young patients. For old patients and patients with a cardiovascular co-morbidity, a slower infusion rate was recommended with a careful follow-up of heart rhythm and blood pressure. No cardiovascular adverse effect was reported in oral phenytoin overdoses except one case with a very high serum phenytoin level and hypoalbuminemia. Phenytoin is an effective and well tolerated drug in the treatment of epilepsy. Intravenous phenytoin is safe when given at recommended infusion rates and doses.

Intravenous lacosamide or phenytoin for treatment of refractory status epilepticus

OBJECTIVES

To compare intravenous phenytoin (PHT) and intravenous lacosamide (LCM) for treatment of status epilepticus after failure of the first and second drug.

METHODS

We retrospectively identified patients from a large community hospital in northern Germany who had been diagnosed with SE between August 2008 and December 2010. Patients who had failed to respond to the first two drugs were selected for this analysis.

RESULTS

Forty-six patients (23 female, median age 68 years) were identified. LCM was used as third drug in 21 patients (median bolus 400 mg) and PHT in 15 patients (median bolus 1500 mg). Pretreatment was similar regarding substance groups (benzodiazepine as first line, levetiracetam as second line drug) and bolus doses. Status epilepticus was terminated in six patients (40%) of the PHT group and in seven patients (33%) of the LCM group. Four patients (27%) of the PHT group and no patient of the LCM group suffered from a relevant, treatment-related side effect during administration of the third drug.

CONCLUSION

Lacosamide and PHT showed similar success rates for treatment of SE when used after failure of benzodiazepines and levetiracetam. However, PHT was associated with relevant side effects that were not seen with LCM.

Requirement for cardiac telemetry during intravenous phenytoin infusion: guideline fact or guideline fiction?

Guidelines recommend the use of cardiac telemetry when phenytoin is administered intravenously. Clinical areas where telemetry is available may not always be the most suitable place to monitor and treat these sick patients. We sought to clarify the evidence regarding the need for cardiac telemetry during intravenous infusion of phenytoin.

Tolerability, safety, and side effects of levetiracetam versus phenytoin in intravenous and total prophylactic regimen among craniotomy patients: a prospective randomized study

PURPOSE

Practical choice in parenteral antiepileptic drugs (AEDs) remains limited despite formulation of newer intravenous agents and requirements of special patient groups. This study aims to compare the tolerability, safety, and side effect profiles of levetiracetam (LEV) against the standard agent phenytoin (PHT) when given intravenously and in total regimen for seizure prophylaxis in a neurosurgical setting.

METHODS

This prospective, randomized, single-center study with appropriate blinding comprised evaluation pertaining to intravenous use 3 days following craniotomy and at discharge, and to total intravenous-plus-oral AED regimen at 90 days. Primary tolerability end points were discontinuation because of side effect and first side effect. Safety combined end point was major side effect or seizure. Seizure occurrence and side effect profiles were compared as secondary outcomes.

KEY FINDINGS

Of 81 patients randomized, 74 (36 LEV, 38 PHT) received parenteral AEDs. No significant difference attributable to intravenous use was found between LEV and PHT in discontinuation because of side effect (LEV 1/36, PHT 2/38, p = 1.00) or number of patients with side effect (LEV 1/36, PHT 4/38, p = 0.36). No significant difference was found between LEV and PHT total intravenous-plus-oral regimen in discontinuation because of side effect (hazard ratio [HR] 0.78, 95% confidence interval [CI] 0.21-2.92, p = 0.72) or number of patients with side effect (HR 1.51, 95% CI 0.77-2.98, p = 0.22). More patients assigned PHT reached the undesirable clinical end point for safety of major side effect or seizure (HR 0.09, 95% CI 0.01-0.70, p = 0.002). Seizures occurred only in patients assigned PHT (n = 6, p = 0.01). Although not significant, trends were observed for major side effect in more patients assigned PHT (p = 0.08) and mild side effect in more assigned LEV (p = 0.09).

SIGNIFICANCE

Both LEV and PHT are well-tolerated perioperatively in parenteral preparation, and in total intravenous-plus-oral prophylactic regimen. Comparative safety and differing side effect profile of intravenous LEV supports use as an alternative to intravenous PHT.

Review article: phenytoin use and efficacy in the ED

This article reviews the evidence regarding the use of phenytoin in adult and paediatric patients experiencing seizures in the ED in Australasia, including relevant pharmacokinetics, dosage, therapeutic drug monitoring and methods of administration. It summarizes current evidence regarding the use of phenytoin in a number of seizure types commonly seen in ED. A search of Medline, Embase and Cochrane was performed using appropriate keyword and MeSH headings. A loading dose of phenytoin should be given to phenytoin naïve patients for the emergency treatment of seizures; parenteral administration results in therapeutic concentration sooner than oral administration but is associated with more frequent and significant adverse effects. Diluting phenytoin is safe but there is limited evidence regarding adverse effects of diluted phenytoin; a filter is probably not needed. Free phenytoin concentrations correlate best with antiseizure efficacy. Phenytoin is used in the treatment of status epilepticus although evidence here is limited; it may also be given to prevent early post-traumatic seizures. It should not be given to treat or prevent eclamptic or alcohol-related seizures. There is insufficient evidence regarding its use in preventing febrile convulsions, treating or preventing seizures due to space occupying lesions or intracerebral haemorrhage and thrombosis. In conclusion, phenytoin is appropriate for treatment of some seizures seen in the ED; it is associated with significant adverse effects; trials are ongoing regarding the use of other anticonvulsants in the treatment of status epilepticus.

Cost-effectiveness of nonemergency use of phenytoin

Parenteral phenytoin is an effective agent used to manage seizures, but it is associated with adverse effects and must be given intravenously. Fosphenytoin is higher in drug cost, but is more soluble, better tolerated and can be infused at rates three times that of phenytoin. When infusion rate is not an issue the adverse effect risk becomes a focus of concern, as well as cost. The determination of the point at which the treatment costs of infusion-related adverse effects of phenytoin outweigh the drug costs of fosphenytoin has been attempted through various clinical economic analyses. Strategies developed to promote the safe use of intravenous phenytoin are based on patient selection, recommended administration methods and patient monitoring. When rapid attainment of serum phenytoin levels is required or in patients at high risk of adverse effects secondary to parenteral phenytoin, fosphenytoin is clearly preferred. This review will focus on the implications of the use of parenteral phenytoin products in the nonemergent setting where potential adverse effects of parenteral phenytoin may be avoided with use of established criteria for patient selection and administration.

Life-threatening adverse events of antiepileptic drugs

Treating a patient with antiepileptic drugs (AEDs) may give rise to unexpected life-threatening adverse events. Despite extensive experimental and clinical testing to ensure safety, most AEDs on the market have been associated with cases of severe cutaneous reactions, serious hematological disorders, or hepatic failure. Most of these disorders emerge as idiosyncratic immune-mediated disease or are related to toxic metabolic products of the AEDs. Early diagnosis is the only means of reducing the harmful, potentially fatal effects of these reactions. A high degree of suspicion, knowledge of risk factors, and close physician-patient contact increases the likelihood of early diagnosis and treatment. When diagnosed, severe reactions must be fully documented and reported to health authorities. The very rare occurrence of life threatening events should not, in general, limit treatment decision-making. Future epidemiological, chemical, and genetic research might provide methods for ascertaining which patients are at risk, so undue exposure can be avoided.

Fosphenytoin: an intravenous option for the management of acute trigeminal neuralgia crisis

Timely management of trigeminal neuralgia presenting with severe, sustained, crescendo pain can be difficult with oral medications. More rapid pain control often can be achieved using intravenous phenytoin. Fosphenytoin is a phosphate ester prodrug of phenytoin that is significantly better tolerated parenterally than phenytoin in the treatment of epilepsy. Three patients with trigeminal neuralgia refractory to oral medications and presenting with crisis pain were treated urgently with intravenous fosphenytoin. In each case complete relief of pain was achieved for a duration of two days, affording a window of opportunity to modify oral pharmacotherapeutic strategies or to control pain in preparation for invasive neurosurgical intervention.