RESUMEN
OBJECTIVE: To study the influence of suspending agents on the relative bioavailability of Cyclosporine A-loaded HPMCP(HP55) nanoparticles for oral administration. METHODS: Suspending agents such as Vanzan, HPMC, Carbopol were added into cyclosporine A-loaded HP55 nanoparticles. The suspended nanoparticle formulations and Neoral were administered orally in a dosage of 15 mg/kg to rats. The CyA concentrations in the blood sample were determined by HPLC. Pharmacokinetic parameters were calculated by 3P97. RESULTS: The concentration-time data of these preparations were best fit by two compartment model with a weight of 1/C(2). Compared with the reference Neoral microemulsion, the relative bioavailability of 2 g/L Carbopol, 5 g/L Vanzan, 8, 5, 3 g/L HPMC suspended nanoparticles were 70.2%, 84.3%, 90.0%, 94.5% and 97.7%, respectively. Their viscosity values were 550, 362, 105, 30 and 15 mPaxs, respectively. CONCLUSION: With the increase in viscosity, the relative bioavailability of nanoparticle formulations decreased. So, it is important to select the appropriate viscosity of suspending agents in the formulation design.