RESUMEN
Mirtazapine (MZPc) is an antidepressant drug which is approved by the FDA. It has low bioavailability, which is only 50%, in spite of its rapid absorption when orally administered owing to high first-pass metabolism. This study was oriented towards delivering intranasal (IN) mirtazapine by a direct route to the brain by means of preparing lipid nanocapsules (LNCs) as a targeted drug delivery system. MZP-LNCs were constructed by solvent-free phase inversion temperature technique applying D-Optimal mixture design to study the impact of 3 formulation variables on the characterization of the formulated nanocapsules. Independent variables were percentage of Labrafac oil, percentage of Solutol and percentage of water. Dependent variables were particle size, polydispersity index (PDI), Zeta potential and solubilization capacity. Nanocapsules of the optimized formula loaded with MZP were of spherical shape as confirmed by transmission electron microscopy with particle diameter of 20.59 nm, zeta potential of - 5.71, PDI of 0.223 and solubilization capacity of 7.21 mg/g. The in vivo pharmacokinetic behavior of intranasal MZP-LNCs in brain and blood was correlated to MZP solution after intravenous (IV) and intranasal administration in mice. In vivo biodistribution of the drug in mice was assessed by a radiolabeling technique using radioiodinated mirtazapine (131I-MZP). Results showed that intranasal MZP-LNCs were able to deliver higher amount of MZP to the brain with less drug levels in blood when compared to the MZP solution after IV and IN administration. Moreover, the percentage of drug targeting efficiency (%DTE) of the optimized MZP-LNCs was 332.2 which indicated more effective brain targeting by the intranasal route. It also had a direct transport percentage (%DTP) of 90.68 that revealed a paramount contribution of the nose to brain pathway in the drug delivery to the brain.
Asunto(s)
Administración Intranasal , Encéfalo , Lípidos , Mirtazapina , Nanocápsulas , Animales , Mirtazapina/farmacocinética , Mirtazapina/administración & dosificación , Mirtazapina/química , Encéfalo/metabolismo , Distribución Tisular , Nanocápsulas/química , Lípidos/química , Lípidos/farmacocinética , Lípidos/administración & dosificación , Masculino , Ratones , Sistemas de Liberación de Medicamentos , Tamaño de la Partícula , Radioisótopos de Yodo/farmacocinética , Radioisótopos de Yodo/administración & dosificación , Mucosa Nasal/metabolismo , Mianserina/farmacocinética , Mianserina/administración & dosificación , Mianserina/química , Mianserina/análogos & derivados , Mianserina/sangreRESUMEN
OBJECTIVE: Clonazepam (CP) is a potent long-acting nitrobenzodiazepine derivative that could be used for targeting peripheral benzodiazepine receptors. Phospholipid magnesome is a new vesicular nanosystem recently developed for brain targeting. Improving the uptake of 131I-CP to the brain might be effective for the diagnosis and/or radiotherapy of certain brain diseases and/or tumors. METHODS: CP was radiolabeled with 131I using direct electrophilic substitution reaction. Quality control of 131I-CP was performed using different techniques. Different formulas of 131I-CP were prepared and characterized according to particle size and polydispersity index. The structural features of the optimized formula were then interpreted using transmission electron microscopy and scanning electron microscopy, whereas pharmacokinetic and in vivo behaviors were estimated using the intravenous and intranasal delivery routes. RESULTS: The heart and blood demonstrated lower uptake of 131I-CP, which inevitably decreased the nontarget effects of radioiodine. Intranasally administered 131I-CP-loaded magnesomes (INMg) had noticeably higher brain uptake (7.1 ± 0.09%ID/g) with rapid onset of action within 5 min and effective pharmacokinetic behavior. INMg had a drug targeting efficiency and nose-to-brain direct transport percentage of 121.1% and 94.6%, respectively as well as a relative bioavailability of 441.04 ± 75.5%. CONCLUSION: The present study showed that 131I-CP-loaded magnesomes can be a beneficial brain-targeting approach for improving the diagnosis and/or radiotherapy of certain brain diseases.