(M1330-01-08) Comparing the Efficacy of Intranasal Midazolam, Diazepam and Lorazepam as First-Line Treatments of Acute Seizures: Pilot Investigation in Pilocarpine-Induced Mice Model

Purpose: Epilepsy is a central nervous system disease characterized by sudden onset of seizures, loss of consciousness, or confusion. In recent years, many non-intravenous routes of administration of benzodiazepines have been developed for seizure control, with intranasal administration being an attractive route of choice. However, for such route of administration, there lacks evidence on the choice of the epilepsy drug. This study aims to compare the intranasal formulations of three first-line drugs for seizure control, namely midazolam, diazepam, and lorazepam, via an ideal intranasal treatment.

Methods: A pilocarpine-induced seizure model in mice was used to compare drug efficacy. The three drugs were administered intranasally to 36 C57 mice at a single dose of 1 mg/kg followed by inducing the seizures via intraperitoneal injection of pilocarpine. The subsequent seizure scores were observed for either 10 or 100 minutes. After sacrificing the mice at 10- or 100-minutes post-dosing, whole brain tissue and plasma were collected to analyze the drug concentrations as well as brain-to-plasma concentration ratios. In addition, drug bindings to plasma and brain tissue obtained using ultrafiltration method were compared; and drug binding affinities towards GABA_A receptor obtained via computer docking technique were also compared.

Results: Among the three tested drugs, our results suggested that intranasal diazepam with the highest brain-to-plasma ratio (Figure 1) was the best in seizure control at 10 minutes (Figure 2). Although all three drugs showed good stability, similar brain binding and receptor binding affinity, diazepam demonstrated the lowest plasma protein binding (Figure 3), which could contribute to its higher brain-to-plasma ratio and better acute epilepsy control than the other two drugs.

Conclusion: Our pilot in-vivo experiments in pilocarpine-induced mice seizure model suggested that intranasally administered benzodiazepines are effective, with intranasally delivered diazepam being the best for seizure control at the early stage of seizure.


Figure 1. Comparison of mean brain-to-plasma concentration ratios of midazolam, diazepam and lorazepam after intranasal administration of lorazepam (1 mg/kg), diazepam (1 mg/kg) and midazolam (1 mg/kg) to pilocarpine-induced C57 mice at 10 and 100 min. *p < 0.05, **p < 0.01, ***p < 0.001 compared within treatment groups.


Figure 2. Comparison of seizure scores after intranasal administration of vehicle (control), midazolam (1 mg/kg), diazepam (1 mg/kg) and lorazepam (1 mg/kg) in pilocarpine-induced C57 mice. *p < 0.05, **p < 0.01, ***p < 0.001 compared with control; NULLp < 0.01, NULL#p < 0.001 compared within treatment groups.


Figure 3. Arene-cation interactions between residues (Lys199, Arg257) of HSA and the studied three benzodiazepines (a: diazepam; b: midazolam; c: lorazepam).