Bioavailability and safety of diazepam intranasal solution compared to oral and rectal diazepam in healthy volunteers.

OBJECTIVE: The study assesses the bioavailability of diazepam after intranasal administration (diazepam nasal spray) in healthy volunteers. Comparative agents were diazepam rectal gel, which served as the regulatory reference product; and oral diazepam, a product with decades of clinical use. Tolerability of diazepam nasal spray was also assessed. METHODS: This was a phase 1, open-label, randomized, single-dose, three-treatment, three-period, six-sequence crossover study in 48 healthy adult subjects that consisted of a screening period, a baseline period, and an open-label treatment period. Interperiod intervals were at least 28 days. RESULTS: Forty-eight healthy volunteer subjects were enrolled, two of whom discontinued before receiving study medication. For all routes of administration, the onset of diazepam absorption was rapid, with measurable concentrations of drug present by the first sample time point. The tmax (time to reach maximum plasma concentration) was similar for diazepam nasal spray and diazepam rectal gel, both of which were slower than oral diazepam in fasted individuals. Variability (as defined by % coefficient of variation of geometric mean) in peak plasma concentration and area under the curve0-∞ was lowest with oral diazepam, followed by diazepam nasal spray, with diazepam rectal gel showing the greatest variability. Overall, 131 treatment-emergent adverse events (TEAEs) were considered mild (42 subjects, 91.3%), four TEAEs were considered moderate (four subjects, 8.3%), and no TEAEs were considered severe. The most commonly reported TEAE was somnolence at 56.5% (26/46) during diazepam nasal spray treatment, 89.1% (41/46) with the rectal diazepam gel treatment, and 82.6% (38/46) with oral diazepam treatment. No nasal irritation was observed for the majority of the subjects at any time point after administration, with no score higher than 2 ("minor bleeding that stops within 1 minute"). SIGNIFICANCE: Diazepam nasal spray shows predicable pharmacokinetics and represents a potential novel therapeutic approach to control bouts of increased seizure activity (cluster seizures, acute repetitive seizures).

Evaluation of Pharmacokinetics and Dose Proportionality of Diazepam After Intranasal Administration of NRL-1 to Healthy Volunteers.

NRL-1 is a novel intranasal formulation of diazepam that is being evaluated as rescue medication in patients with epilepsy who experience bouts of increased seizure activity despite stable regimens of antiepileptic drugs. This phase 1, open-label, randomized, crossover study in healthy adult volunteers consisted of 3 single-dose periods (5, 10, and 20 mg) followed by a 2-dose period (2 × 10 mg) with a minimum 28-day washout between treatments. Blood samples were taken at prespecified time points after intranasal dosing, and bioanalytic analysis of diazepam and nordiazepam was conducted using a validated liquid chromatography-tandem mass spectrometry method. Plasma pharmacokinetic parameters were summarized using descriptive statistics, and dose proportionality (peak concentration [Cmax ] and area under the plasma concentration-time curve [AUC0-∞ ]) was evaluated based on a power model within a 90%CI of 0.84 to 1.16. Comparisons were also conducted between single 10-mg dose and multidose (2 × 10 mg) treatments. NRL-1 administration resulted in rapid diazepam absorption (median time to peak concentration 1.4-1.5 hours). Plasma concentration-time profiles showed similar patterns of exposure that appeared to be dose dependent, with Cmax of 85.6, 133.6, and 235.3 ng/mL for the 5-, 10-, and 20-mg doses, respectively, although the lower 90%CI for Cmax and AUC0-∞ exceeded dose proportionality criteria. The coefficient of variation ranged from 59% to 67% for Cmax and 48% to 56% for AUC parameters. Dose-normalized AUC0-∞ values were comparable between the 2 × 10-mg and single 10-mg doses. Treatment-emergent adverse events were consistent with those expected for diazepam, with transient somnolence the most frequent adverse event (94.4%). These results support NRL-1 as a potential therapy for managing seizure emergencies.