Nano-Engineered Cargo for Optimizing Oral Absorption of Tizanidine Nanostructured Lipid Carriers

Tizanidine (TNZ) is a muscle relaxant that works by blocking presynaptic neurons. Due to its inadequate solubility and low oral bioavailability, this medication is classified as a Biopharmaceutics Classification System (BCS) class II drug. The objective of this study was to improve the absorption of TNZ using nanostructured lipid carrier (NLCs) as a method of delivering the medicine.

To achieve this objective, NLCs were synthesized using microemulsion techniques. The optimization process was conducted using Design Expert version 12 Box Behnken model. The parameters of interest were mean particle size (PS), zeta potential (ZP), and percent entrapment efficiency (EE%). The concentrations of the medication, lipid, and surfactant were varied during the optimization process. Further characterization included Fourier transform infrared spectroscopy (FTIR) and powdered X-ray diffraction (PXRD). The optimized formulation was subsequently tested for in-vitro release under varying pH conditions. The pharmacokinetic study was elicited to assess the oral bioavailability of the TNZ-NLCs in comparison to its suspension.

The formulation was tuned to have PS of 208 nm, a polydispersity index (PDI) of 0.221, a ZP of -18.6 mV, and an EE% of 93%. The optimized formulation remained physically stable for 12 weeks under various temperatures. The pharmacokinetic study indicated a 21-fold enhancement in AUC due to entrapment of TNZ into NLCs thereby, aligning with the aim to improve bioavailability.

It was inferred that the inclusion of TNZ within NLCs results in its controlled release with enhanced bioavailability.