Brain-targeted intranasal zaleplon solid dispersion in hydrophilic carrier system; 23 full-factorial design and in vivo determination of GABA neurotransmitter

Prolonged Zaleplon Treatment Increases the Expression of Proteins Involved in GABAergic and Glutamatergic Signaling in the Rat Hippocampus

Zaleplon is a positive allosteric modulator of the γ-aminobutyric acid (GABA)A receptor approved for the short-term treatment of insomnia. Previous publications on zaleplon have not addressed the proteins involved in its mechanism of action but have mostly referred to behavioral or pharmacological studies. Since both GABAergic and glutamatergic signaling have been shown to regulate wakefulness and sleep, we examined the effects of prolonged zaleplon treatment (0.625 mg/kg for 5 days) on these systems in the hippocampus of male Wistar rats. Western blot and immunohistochemical analyses showed that the upregulated components of GABAergic signaling (glutamate decarboxylase, vesicular GABA transporter, GABA, and α1 subunit of the GABAA receptor) were accompanied by increased protein levels in the glutamatergic system (vesicular glutamate transporter 1 and NR1, NR2A, and NR2B subunits of N-methyl-d-aspartate receptor). Our results, showing that zaleplon enhances GABA neurotransmission in the hippocampus, were not surprising. However, we found that treatment also increased glutamatergic signaling. This could be the result of the downregulation of adenosine A1 receptors, important modulators of the glutamatergic system. Further studies are needed to investigate the effects of the zaleplon-induced increase in hippocampal glutamatergic neurotransmission and the possible involvement of the adenosine system in zaleplon's mechanism of action.

Improved drug transfer into brain tissue via the "nose-to-brain" approach using suspension or powder formulations based on the amorphous solid dispersion technique

Intranasal administration has attracted increasing attention as a drug delivery approach based on nose-to-brain drug delivery from the nasal cavity to brain tissue directly, bypassing the blood-brain barrier. However, application of the method to poorly water-soluble drugs is potentially limited due to low aqueous solubility and dissolution, which can hinder drug transfer to brain tissue. In the present study, we focused on an amorphous solid dispersion (ASD) technique to improve drug dissolution. A carbamazepine-loaded ASD model drug was prepared using the solvent evaporation method (ASD-1). After screening six water-soluble polymer carriers, polyvinyl alcohol (PVA)-based ASD-1 formulation exhibited the most rapid and highest drug dissolution under experimental conditions in the nasal cavity (pH 6.0). A carbamazepine suspension dispersed with a PVA-ASD-1 formulation exhibited enhanced drug delivery into plasma and brain tissue of rats in vivo. A spray-dried powder formulation of PVA-ASD (PVA-ASD-2) exhibited improved drug dissolution and in vivo drug transfer. Our key finding is that the spray-dried PVA-ASD-2 formulation exhibited higher brain/plasma ratios than the PVA-ASD-1 suspension formulation. Our physical characterization data and demonstration of improved drug transfer suggest that ASD-based intranasal formulations hold promise for drug delivery to the brain.

Rapid oral transmucosal delivery of zaleplon-lavender oil utilizing self-nanoemulsifying lyophilized tablets technology: development, optimization and pharmacokinetic evaluation

Based on the administration convenience, transmucosal buccal drug delivery allows special strength points over peroral routes for systemic delivery. It could achieve local or systemic effect and boost drugs’ bioavailability for agents with first pass metabolism. The current study aimed to manufacture and optimize a lavender oil–based nanoemulsion loaded with zaleplon and incorporate it into fast-disintegrating tablets to promote its dissolution and oral bioavailability via oral mucosa. Zaleplon-loaded nanoemulsions were devised with various levels of lavender oil (10% to 25%), the surfactant Sorbeth-20 (35% to 65%), and the co-surfactant HCO-60 (20% to 40%); the extreme vertices mixture statistical design was adopted. The droplet size and drug-loading efficiency were the evaluated. The optimal formulation was transformed into self-nanoemulsified lyophilized tablets (ZP-LV-SNELTs), which were tested for their uniformity of content, friability, and disintegration time with in-vitro release. Finally, the pharmacokinetic parameters of the ZP-LV-SNELTs were determined and compared with those of marketed formulations. The optimal nanoemulsion had a droplet size of 87 nm and drug-loading capacity of 185 mg/mL. ZP-LV-SNELTs exhibited acceptable friability and weight uniformity and a short disintegration time. The in-vitro release of ZP-LV-SNELTs was 17 times faster than that of the marketed tablet. Moreover, the optimal ZP-LV-SNELTs increased the bioavailability of zaleplon in rabbits by 1.6-fold compared with the commercial tablets. Hence, this investigation revealed that ZP-LV-SNELTs delivered zaleplon with enhanced solubility, a fast release, and boosted bioavailability thru oral mucosa which provided a favorable route for drug administration which is suggested to be clinically investigated in future studies