Intranasal carvacrol nanoemulsion: Stroke imaging and neuroprotective study
Hitendra Mahajan1, Ghanashyam Girnar1
1Department of Pharmaceutics, R. C. Patel Institute of Pharmaceutical Education and Research, Shirpur, Maharashtra, India.
Background And Purpose:
Cerebral ischemia causes neuronal damage due to restricted blood flow and presents significant challenges for brain-targeted drug delivery because of the blood-brain barrier. The purpose of this study is to formulate and evaluate an intranasal oil-in-water nanoemulsion of carvacrol, a neuroprotective agent, for direct nose-to-brain delivery in treating cerebral ischemia.
Experimental Approach:
Nanoemulsions were developed using high-pressure homogenization and optimized by adjusting surfactant mixture ratios and homogenization cycles. Characterization included droplet size (<200 nm), polydispersity index, zeta potential, drug content, transmission electron microscopy (TEM), and drug release profiles. Intranasal suitability was assessed through in vitro, ex vivo and in vivo studies, including pharmacokinetics, single photon emission computed tomography (SPECT) imaging, and evaluation in a middle cerebral artery occlusion rat model.
Key Results:
The optimized nanoemulsion showed sustained release, enhanced nasal permeation, and significantly improved brain bioavailability (C max = 67.79 ng mL-1 intranasal vs. 49.71 ng mL-1 intravenous). Lower systemic exposure and high targeting indices (DTE: 1317 %; DTP: 92.40 %) confirmed efficient brain delivery. SPECT imaging validated localized uptake, and the ischemia model demonstrated strong neuroprotective efficacy.
Conclusion:
Intranasal carvacrol-loaded nanoemulsion is a promising non-invasive strategy for cerebral ischemia treatment, enabling effective brain targeting and significant therapeutic benefit.
