RESUMEN
Objective To determine equilibrium solubility and apparent partition coefficient of salicylic acid at 25 ℃,and to provide a theoretical basis for design and preparation of its formulation.Methods Equilibrium solubility and apparent partition coefficient (Papp) of salicylic acid were respectively investigated in water,hydrochloric acid solution (pH 1.0) and phosphate buffer solution system (pH 2.0,3.0,4.0,5.0,6.0,7.0,7.8) at 25 ℃.The shake flask method and HPLC were used.The column was Waters C18 (4.6 mm ×250 mm,5 μn) with the mobile phase as methanol-0.1％ phosphoric acid water (47:53).The column temperature was room temperature.The flow rate was 1.0 mL·min-1.The detection wavelength was 270 nm and injection volume was 20 μL.Results Equilibrium solubility of salicylic acid was (2.205 ±0.020) mg·mL-1 at 25 ℃ in Water and its Papp was (6.18 ±0.08).The solubility were (1.169 × 10-3 ±7.40 × 10-6),(2.250 ±0.010),(2.410±0.010),(2.694 ±0.003),(5.208 ±0.010),(5.826 ±0.006),(6.255 ±0.030),(3.353 ±0.070) mg·mL-1,respectively,at hydrochloric acid solution (pH 1.0) and phosphate buffer solution system (pH 2.0,3.0,4.0,5.0,6.0,7.0,7.8),and the corresponding Papp were (16.39 ±0.19),(4.23 ±0.07),(6.03 ±0.11),(5.56 ±0.10),(1.25 ±0.01),(0.27 ± 0.001),(0.08 ± 0.001) and (0.07 ± 0.002),respectively.Conclusion The solubility of salicylic acid increases and its oil-water partition coefficient declines with pH value increasing.Salicylic acid is slightly soluble in water and oil.It belongs to Class Ⅳ drug in Biopharmaceutics Classification System (BCS).
RESUMEN
AIM: To explore the appearent partition coefficient of flavonoids from Hawthorn leaf in phospholids complex. METHODS: With the aid of the shake-flask method,The contents of rhamnosylvitexin,rutin and quercetin were determined by HPLC and apparent partition coefficient in the system of n-octyl alcohol and water of each ingredient in the physical mixture of Hawthorn leaf flavonoids and phospholipids,Hawthorn leaf flavonoids and its phospholipids complex were calculated respectively. RESULTS: Apparent partition coefficient of rhamnosylvitexin and rutin and quercetin in phospholipids complex were enhanced comparing with both in Hawthorn leaf flavonoids and the physical mixture of Hawthorn leaf flavonoids and phospholipids. CONCLUSION: Phospholipid complex may be an effective carrier to elevate the oral bioavailability of total flavonoids from effective fraction of Hawthorn leaf.