Contribution of both olfactory and systemic pathways for brain targeting of nimodipine-loaded lipo-pluronics micelles: <i>in vitro</i> characterization and <i>in vivo</i> biodistribution study after intranasal and intravenous delivery

Abstract

Nimodipine (NM) is the only FDA-approved drug for treating subarachnoid hemorrhage induced vasospasm. NM has poor oral bioavailability (5-13%) due to its low aqueous solubility, and extensive first pass metabolism. The objective of this study is to develop radiolabeled NM-loaded LPM and to test its ability prolong its circulation time, reduce its frequency of administration and eventually target it to the brain tissue. NM was radiolabeled with ^99mTc by direct labeling method using sodium dithionite. Different reaction conditions that affect the radiolabeling yield were studied. The in vivo pharmacokinetic behavior of the optimum NM-loaded LPM formulation in blood, heart, and brain tissue was compared with NM solution, after intravenous and intranasal administration. Results show that the radioactivity percentage (%ID/g) in the heart of mice following administration of ^99mTc-NM loaded LPM were lower compared with that following administration of ^99mTc-NM solution, which is greatly beneficial to minimize the cardiovascular side effects. Results also show that the %ID/g in the blood, and brain following intravenous administration of ^99mTc-NM-loaded LPM were higher at all sampling intervals compared with that following intravenous administration of ^99mTc-NM solution. This would be greatly beneficial for the treatment of neurovascular diseases. The drug-targeting efficiency of NM to the brain after intranasal administration was calculated to be 1872.82%. The significant increase in drug solubility, enhanced drug absorption and the long circulation time of the NM-loaded LPM could be promising to improve nasal and parenteral delivery of NM.