ABSTRACT
A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to determine the plasma concentration of progesterone in Beagle dogs, and apply it to the study of the pharmacokinetics of progesterone sustained-release formulation in Beagle dogs. The plasma samples were processed by protein precipitation method and megestrol acetate was used as an internal standard (IS). The quantitation analysis was performed using multiple-reaction monitoring (MRM) mode at the specific ion transitions of m/z 315.2→97.0 for progesterone and m/z 385.2→267.1 for megestrol acetate (IS) under the positive ion condition. Male Beagle dogs were injected intramuscularly with progesterone sustained-release microspheres and the plasma samples were collected at different time points after administration. The relevant pharmacokinetic parameters were calculated by WinNonlin 8.1 software. A good linearity over the range of 0.1-500.0 ng·mL-1 was yielded by this method. The intra- and inter-day precision (RSD) were all less than 13.25% and the accuracy (RE) was within 8.92%. Stability test showed that progesterone in dog plasma was stable at room temperature for 12 h, up to 60 days at -20 ℃ and after three cycles of freeze-thaw. The recovery of it ranged from 71.43%-77.97%. After intramuscular injection of progesterone sustained-release microspheres in Beagle dogs, tmax was 19.00 ± 25.36 h, Cmax was 137.72 ± 11.59 ng·mL-1, t1/2 was 83.83 ± 26.43 h. The drug was released continuously in vivo and in a continuous absorption process for many times with good sustained-release effect. The method developed in this study is sensitive, rapid and stable. It is suitable for the determination of progesterone plasma concentration in Beagle dogs, and can be applied to the preclinical pharmacokinetic study of progesterone-related formulations. The animal experiment scheme of this study was approved by the Animal Ethics Committee of the Academy of Military Medical Sciences.
ABSTRACT
OBJECTIVE: To prepare and evaluate donepezil sustained-release microspheres by ultrasound technique. METHODS: Preparation technology of donepezil biodegradable microspheres by ultrasound technique was established and optimized. In vitro evaluation of donepezil microspheres was carried out. The pharmacokinetics of donepezil microspheres was investigated by LC-MS/MS after subcutaneous injection in rabbits at a dose of 30.0 mg · kg. RESULTS: Donepezil microspheres with drug loading of 12.1% and mean particle size between 40 to 130 μm were successfully prepared by ultrasound technique. The donepezil microspheres displayed a one-month sustained-release character in vitro. The pharmacokinetic parameters were as follows: pmax 40.63 μg · L-1, tmax 2.47 d, MRT 14.81 d, and AUC0→∞ 646.96 μg · d · L-1. CONCLUSION: Ultrasound technique is successfully applied in the preparation of donepezil sustained-release microspheres.
ABSTRACT
Objective To study the pharmacokinetic characters of cyclosporin A(CsA) in aqueous humor in rabbit after implanting different dosages of CsA in eyes and to provide a theoretical basis for the treatment of after cataract. Methods ECCE was performed in all rabbit eyes. CsA-MS was injected into the anterior chamber and the capsular bag in left eyes as expression group and MS was given in the same way in right eyes as control group. The concentration of CsA in the aqueous humor was monitored with high-performance liquid chromatogram. The follow-up period was 4 weeks. The samples were separated on a C18 column at 60℃ and detected at 210nm. The mobile phase was acetonitrile-water (67∶33). Results The correlation analysis showed a positive correlation within the range of 0.13-1.25mg/L (r=0.9951) and the detection limit was 0.13mg/L. The accuracy was 95.91% and the inter-day and intro-day precision was less than 5%. CsA in aqueous humor sustained a high concentration within 2 weeks. There were no significant differences in t1/2Ka and CL between the two dosage groups. AUC and Cmax increased in a dose-dependent manner. Conclusion The sustain-released CsA ophthalmic gels provided significant ocular bioavailability in rabbit eyes and they can reach the therapeutic dose in order to inhibit after cataract.