This review covers intranasal solid lipid nanoparticles (65–210 nm) as a noninvasive platform for direct brain delivery, summarizing in vitro/in vivo findings, patents, and trials across multiple CNS indications including Parkinsonism.

Intranasal SLNs offer a translationally promising route to bypass the BBB and deliver neuroprotective or disease-modifying agents to the brain for Parkinson's, but the paper is a broad delivery-focused review with little Parkinson-specific mechanistic or efficacy data.

The blood-brain barrier (BBB) restricts the passage of drugs into the brain, preventing drug transport to the central nervous system and minimizing the therapeutic effectiveness of several drugs used for brain diseases. The intranasal route of administration provides a non-invasive, quick, and efficient means of achieving direct brain targeting. The anatomy and physiology of the nasal cavity play a vital role in drug absorption and transport to the brain. The olfactory and trigeminal nerves are directly linked to the brain, allowing drugs to bypass the BBB. Solid Lipid Nanoparticles (SLNs) have emerged as a potential drug delivery system for the intranasal administration of therapeutic agents targeting brain diseases. SLNs are composed of biocompatible lipids and surfactants and offer unique advantages, such as controlled drug release, enhancement in bioavailability, and high brain targeting potential. This review focuses on the exploration of drug-loaded intranasally delivered SLNs for brain diseases (Alzheimer's, Huntington's, stroke, epilepsy, depression, meningitis, Parkinsonism, migraine, brain cancer) with emphasis on the in vitro and in vivo findings. In the reviewed literature, the size of drug-loaded SLNs for brain delivery via intranasal administration was found to be in the range of 65-210 nm. Ongoing clinical trials and patents involving SLNs for intranasal delivery further strengthen the enhanced interest in this drug delivery platform for the effective management of brain diseases.