A novel nanosuspension of andrographolide: Preparation, characterization and passive liver target evaluation in rats

Andrographolide (Andro) is an excellent anti-inflammatory bicyclic diterpene γ-lactone. However, the poor solubility limits its application as injection for the treatment of acute inflammation. To meet the clinical needs for emergency, the Andro nanosuspensions injection was first prepared by the wet milling technique. The Andro nanosuspensions were composed of 3% Andro, 5% poloxamer 188 as the non-ionic stabilizer, 0.05% sodium deoxycholate or 0.1% sodium tauroursodeoxy cholate as the ionic stabilizer, and prepared by 350 rpm speed and 12 cycles of grinding with 0.4 mm zirconium oxide pearls. The nanosuspensions showed hexagonal morphology with particle size of 300 nm, and no change in crystalline state of Andro after milling. The nanosuspensions had a significant increase in saturation solubility, and could completely release within 0.25 h (bulk Andro within 24 h). The lyophilized product of Andro nanosuspensions with mannitol (5%) as lyoprotectant had good physical and chemical stability during the 6-month storage period. The pharmacokinetic and tissue distribution results showed that it was rapidly eliminated from the blood and largely distributed in the liver. Overall, the Andro nanosuspensions may be used as a potential formulation for the treatment of liver infections owing to its passive liver targeting function.