[Determination of progesterone concentration in plasma after oral administration of progesterone-loaded lipid nanoparticles in rats].

OBJECTIVE: To establish a RP-HPLC method for determination of plasma progesterone and to apply the method for pharmacokinetics study of progesterone-loaded lipid nanoparticles after oral administration in rats. METHODS: The plasma samples were collected from castrated rat after oral administration of progesterone-loaded lipid nanoparticles and extracted by acetic ether. The determination was performed on a Hypersil C18 column (150 mm X 3.9 mm , 5 microm) with a mobile phase consisting of methanol and water (60:40) at a flow-rate of 0.6 ml/min. The UV detector was at 240 nm and danazol was used as internal standard. RESULT: Good linearity was obtained over the range of 0.02-2 microg/ml progesterone in plasma(r=0.9999, n=3). The quantification limit was (0.02 +/-0.004) microg/ml(n=3) and the limit of detection was 0.005 microg.mL(-1)(S/N = or >3). The inter-and intra-day RSDs were all less than 10% for quality control samples at high-, medium- and low-concentrations. The average absolute recovery rate was 90.5 % and the average method recovery was in the range of 93.4 %-107.5%. The plasma concentration-time curves indicated that tmax was delayed after administration of progesterone-loaded lipid nanoparticles, and the bioavailability was increased significantly, compared with contrast solution. CONCLUSION: The method developed is stable, simple, rapid, accurate, sensitive and applicable for determining plasma concentrations of progesterone of progesterone-loaded lipid nanoparticles in pharmacokinetic studies.