Optimizing clozapine-loaded nanostructured lipid carriers through central composite design for enhance bioavailability in antipsychotic therapy

Abstract

Clozapine (CLZ), a tricyclic dibenzodiazepine antipsychotic drug employed for the treatment of Schizophrenia. However, CLZ's significant first-pass effect, poor water solubility, and low oral bioavailability (27%) limit its potential for therapeutic use. The present investigation aimed to prepare CLZ-loaded nanostructured lipid carriers (NLCs) to improve its solubility, bioavailability, and therapeutic efficacy. The NLCs were prepared using an ultrasonic probe sonication technique using selected solid lipids (Gelucire 44/14), liquid lipids (Labrafil M 1944), and surfactants (Monoemul 80). A central composite design approach was adopted to optimize the NLCs. The optimized CLZ-loaded NLCs were evaluated in terms of particle size, zeta potential, surface morphology, crystallinity, drug loading, and in-vitro CLZ release studies. The optimized CLZ-loaded NLCs showed a particle size, zeta potential, and entrapment efficiency of 115.1 ± 2.48 nm, −17 mV and 96.74 ±1.82%, respectively. The morphology revealed the coarsely spherical shape of NLCs. Fourier transform infrared spectroscopy indicated the physical interaction between the CLZ and lipids rather than chemical interaction. The results of powder X-ray diffraction and differential scanning calorimetry showed the conversion of crystalline to amorphous form of CLZ and distributed molecular level in lipid matrix. In the in-vitro release study, pure CLZ showed 14±1.86% release, whereas CLZ-loaded NLC showed initial burst release (20.0±0.56%) followed by sustained release (69.0±1.03%) up to 24 hours. Collectively, results revealed that the developed novel CLZ-loaded NLCs could be a potential formulation to improve efficacy by increasing solubility and prolonging CLZ release and bioavailability with enhanced patient compliance and reduced side effects.