Critical In Vitro Characterization Methods of Lipid-Based Formulations for Oral Delivery: a Comprehensive Review.

Lipids have been extensively used in formulations to enhance dissolution and bioavailability of poorly water-soluble as well as water-soluble drug molecules. The digestion of lipid-based formulations, in the presence of bile salts, phospholipids, and cholesterol, changes the lipid composition in vivo, resulting in the formation of different colloidal phases in the intestine. Therefore, in vitro characterization and evaluation of such formulations are critical in developing a successful formulation. This review covers comprehensive discussion on in vitro characterization techniques such as solubility, drug entrapment, thermal characterization, dissolution, and digestion of lipid-based formulations.

Lyotropic Liquid Crystalline Nanoparticles of Amphotericin B: Implication of Phytantriol and Glyceryl Monooleate on Bioavailability Enhancement.

Implication of different dietary specific lipids such as phytantriol (PT) and glyceryl monooleate (GMO) on enhancing the oral bioavailability of amphotericin B (AmB) was examined. Liquid crystalline nanoparticles (LCNPs) were prepared using hydrotrope method, followed by in vitro characterization, Caco-2 cell monolayer uptake, and in vivo pharmacokinetic and toxicity evaluation. Optimized AmB-LCNPs displayed small particle size (< 210 nm) with a narrow distribution (~ 0.2), sustained drug release and high gastrointestinal stability, and reduced hemolytic toxicity. PLCNPs presented slower release, i.e., ~ 80% as compared to ~ 90% release in case of GLCNPs after 120 h. Significantly higher uptake in Caco-2 monolayer substantiated the role of LCNPs in increasing the intestinal permeability followed by increased drug titer in plasma. Pharmacokinetic studies demonstrated potential of PT in enhancing the bioavailability (approximately sixfold) w.r.t. of its native counterpart with reduced nephrotoxicity as presented by reduced nephrotoxicity biomarkers and histology studies. These studies established usefulness of PLCNPs over GLCNPs and plain drug. It can be concluded that acid-resistant lipid, PT, can be utilized efficiently as an alternate lipid for the preparation of LCNPs to enhance bioavailability and to reduce nephrotoxicity of the drug as compared to other frequently used lipid, i.e., GMO.

"Liquid Crystalline Nanoparticles": Rationally Designed Vehicle To Improve Stability and Therapeutic Efficacy of Insulin Following Oral Administration.

In the present article we investigate the feasibility of liquid crystalline nanoparticles (LCNPs) to improve the stability and therapeutic efficacy of insulin following oral administration. Compatibility studies of different formulation ingredients with insulin and extensive optimization of different process variables resulted into the formation of LCNPs with particle size of 245.50 ± 6.36 nm, PDI of 0.220 ± 0.042, and zeta potential of -18.30 ± 1.27 mV with an entrapment efficiency of 44.17 ± 1.47%. Mannitol (5% w/v) was identified as a suitable cryoprotectant to produce freeze-dried LCNPs without affecting their critical quality attributes. LCNPs demonstrated excellent stability in simulated biological fluids by simultaneously retaining the chemical and conformational stability of the insulin entrapped within the LCNPs. A sustained release of insulin was observed for up to 24 h in PBS (pH 7.4). Developed LCNPs demonstrated remarkably higher Caco-2 cell uptake in comparison with free insulin-FITC and more than double the cumulative hypoglycemia in comparison with subcutaneously administered insulin solution in diabetic rats. Data in hand suggest that the proposed formulation strategy can be exploited for improving the therapeutic efficacy of biomacromolecules like insulin.