How do lipid-based drug delivery systems affect the pharmacokinetic and tissue distribution of amiodarone? A comparative study of liposomes, solid lipid nanoparticles, and nanoemulsions.

Objectives: Lipid-based drug delivery systems (DDS) can improve the pharmacokinetic (PK) parameters of some drugs. Especially those with a high volume of distribution (Vd) leading to off-target accumulation and toxicity. Amiodarone as an anti-arrhythmic agent induces hypothyroidism and liver disorders limiting its clinical indication.

Materials and methods: In the present study, amiodarone PK parameters and biodistribution after IV administration of four nano-formulations to rats were compared. The formulations were liposomes, solid lipid nanoparticles (SLN), PEGylated SLN (PEG-SLN), and nanoemulsions (NE). All formulations were optimized.

Results: The nanoparticles were spherical with a diameter of 100-200 nm and sustained in vitro drug release in buffer pH 7.4. The best-fitted model for the plasma concentration-time profile was two-compartmental. In vivo studies indicated the most changes in PKs induced after liposome, SLN, and NE administration, respectively. The area under the curve (AUC) and maximum plasma concentration (C_max) of liposomes, SLN, and NE were 22.5, 2.6, 2.46 times, and 916, 58, and 26 times higher than that of amiodarone solution, respectively (P-value<0.05). The heart-to-liver ratio of amiodarone was higher for nano-formulations compared to drug solution except for liposomes.

Conclusion: Lipid-based particles can improve the PK parameters of amiodarone and its distribution in different tissues.