Preparation of solid lipid nanoparticles loaded with garlic oil and evaluation of their in vitro and in vivo characteristics.

Solid lipid nanoparticles (SLN) are colloidal drug carriers and may be suitable for delivery of garlic oil, a nutraceutical with medicinal properties, whose use has been limited by its poor solubility. We tested whether poor solubility of garlic oil would be overcome by complexing with SLN by high-pressure homogenization and ultrasound techniques. The effects of lipid phase, surfactant mixture and loading concentration of garlic oil on particle size and distribution were also investigated.High pressure homogenization technique was used to prepare SLN, using orthogonal experiment method to optimize entrapment efficiency, loading efficiency, and recovery of SLN. Pharmacokinetics of garlic oil loaded solid lipid nanoparticles after oral administration to rats was studied by using LC/MS/MS method.Mean particle size and zeta potential of SLN were, respectively, 106.5 ± 40.3 nm and -30.2 mv. The majority of SLN had a less ordered arrangement of crystals at room temperature, which was beneficial for increasing the drug loading capacity. Drug entrapment efficiency was > 90 percent and showed a relatively long-term physical stability. It was feasible to prepare a lyophilized product with good long-term stability. When 10% trehalose and 5% sucrose were used as cryopreservants, SNL particle size increased from 106.5 nm prior to lyophilisation to 155.3 nm after reconstitution. The garlic oil content in SLN decreased to about 85% (respectively, 34.3 vs. 39.4 mg/mL prior to lyophilisation) due to volatility of garlic oil. Pharmacokinetic studies in rats demonstrated that distribution and elimination of diallyl trisulfide (DATS) and diallyl disulfide (DADS) in garlic oil were rapid. Additionally, elimination of garlic oil-SLN complex is faster than that of garlic oil alone, probably, due to phagocytosis.An SLN complex with garlic oil exhibits characteristics similar to those of parenteral emulsions, even after lyophilization and reconstitution.