Assessment of midazolam pharmacokinetics in the treatment of status epilepticus

Treatment of Refractory Status Epilepticus With Continuous Intravenous Anesthetic Drugs: A Systematic Review

Importance

Multiple continuous intravenous anesthetic drugs (CIVADs) are available for the treatment of refractory status epilepticus (RSE). There is a paucity of data comparing the different types of CIVADs used for RSE.

Objective

To systematically review and compare outcome measures associated with the initial CIVAD choice in RSE in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

Evidence Review

Data sources included English and non-English articles using Embase, MEDLINE, PubMed, and Web of Science (January 1994-June 2023) as well as manual search. Study selection included peer-reviewed studies of 5 or more patients and at least 1 patient older than 12 years with status epilepticus refractory to a benzodiazepine and at least 1 standard antiseizure medication, treated with continuously infused midazolam, ketamine, propofol, pentobarbital, or thiopental. Independent extraction of articles was performed using prespecified data items. The association between outcome variables and CIVAD was examined with an analysis of variance or χ2 test where appropriate. Binary logistic regressions were used to examine the association between outcome variables and CIVAD with etiology, change in mortality over time, electroencephalography (EEG) monitoring (continuous vs intermittent), and treatment goal (seizure vs burst suppression) included as covariates. Risk of bias was addressed by listing the population and type of each study.

Findings

A total of 66 studies with 1637 patients were included. Significant differences among CIVAD groups in short-term failure, hypotension, and CIVAD substitution during treatment were observed. Non-epilepsy-related RSE (vs epilepsy-related RSE) was associated with a higher rate of CIVAD substitution (60 of 120 [50.0%] vs 11 of 43 [25.6%]; odds ratio [OR], 3.11; 95% CI, 1.44-7.11; P = .006) and mortality (98 of 227 [43.2%] vs 7 of 63 [11.1%]; OR, 17.0; 95% CI, 4.71-109.35; P < .001). Seizure suppression was associated with mortality (OR, 7.72; 95% CI, 1.77-39.23; P = .005), but only a small subgroup was available for analysis (seizure suppression: 17 of 22 [77.3%] from 3 publications vs burst suppression: 25 of 98 [25.5%] from 12 publications). CIVAD choice and EEG type were not predictors of mortality. Earlier publication year was associated with mortality, although the observation was no longer statistically significant after adjusting SEs for clustering.

Conclusions and Relevance

Epilepsy-related RSE was associated with lower mortality compared with other RSE etiologies. A trend of decreasing mortality over time was observed, which may suggest an effect of advances in neurocritical care. The overall data are heterogeneous, which limits definitive conclusions on the choice of optimal initial CIVAD in RSE treatment.

Pharmacokinetic Modeling of Optimized Midazolam and Pentobarbital Dosing Used in Treatment Protocols of Refractory Status Epilepticus

OBJECTIVES

To model bolus dosing, infusion rate, and weaning rate on theoretical serum concentration of midazolam and pentobarbital used in the treatment of refractory status epilepticus (RSE).

DESIGN

One- and two-compartment in silico pharmacokinetic models of midazolam and pentobarbital.

SETTING

Not applicable.

SUBJECTS

Not applicable.

INTERVENTIONS

We compared the model variables used in midazolam and pentobarbital protocols for standard RSE.

MEASUREMENTS AND MAIN RESULTS

Standard RSE treatment protocols result in steady-state serum concentrations that are 6.2-9.0-fold higher for the one-compartment model and 2.3-4.7-fold higher for the two-compartment model. In the model, not including bolus doses delays the achievement of serum steady-state concentration by 0.5 and 2.7 hours for midazolam and pentobarbital, respectively. Abrupt discontinuation of these medications reduces modeled medication exposure by 1.1 and 6.4 hours, respectively.

CONCLUSIONS

Our in silico pharmacokinetic modeling of standard midazolam and pentobarbital dosing protocols for RSE suggests potential variables to optimize in future clinical studies.