| Objective:The aim of this paper is investigating the pharmacokinetics and pharmacodynamics of a new type preparation of oral insulin named enteric insulin capsule, YSM1591 through the random cross experiment in Beagles and recearching the impact of different administration ways.On the other hand exploring the transmembrane transport mechanism of insulin through the monalayer Caco-2 cell model. The potential clinical application of YSM1591 will be also evaluated to offer more evidence for its clinical evaluation.Methods: 1. The receach on the pharmacodynamics of YSM1591 was completed as follows. Six healthy Beagle dogs were used and were administrated in oral way?in duodenal way and in subcutaneous injection at a single dose by three cross self controls. The doses of the oral way and duodenal way were both at 8 mg/dog(about 200 IU/dog) taking the s.c. as reference preparation(5 IU/dog). The plasmas were sampled at different time points after subcutaneous administration and the blood glucose levels were determined by Roche Glucose meter synchronously. The pharmacodynamics of different insulin preparations were compared by blood glucose concentration, the lowest blood glucose concentration and the sustain time of the pharmacodynamics.2. The research on the pahamacokinetics of YSM1591 was accomplished as follows. The 6 dogs were divided in 3 group and administrated as the recearch of the pharmacodynamics described. After administration of insulin, the blood were sampled at 0, 0.167, 0.333, 0.5, 1, 1.5, 2, 3, 4 and 6 h and each dog was sampled about 2.5 m L blood at each time point. The radioimmunoassay(RIA) method was used to determine the concentration of blood insulin at the different sample points. The concentration of C-peptide were measured by 125I-labeled radio-immunologic kit. Evaluation indicator for the drug concentration of exogenous insulin, pharmacokinetic parameters.3. The research on the vitro absorption mechanism of oral insulin preparation YSM1591 was as follows. Firstly, the Caco-2 cells will be inoculated on the Transwell membrane in a panel with 12 wells. The intergrity and function of the Caco-2 monalayer will be checked. The successful model will be used to investigate the transmembrane uptake of insulin from apical side(AP) to basolateral side(BL)by adding three different dose of insulin(at 0.3, 1 and 3 U/m L). The 125I-labeled RIA Kit will be used to determine the concerntration of insulin in the basolateral side to forecast the possible uptake mechanism of the insulin.Results: 1. The results of the pharmacodynamics showed that the YSM1591 effected eimmediately after 0.5 h and after about 1 hour(1.00±0.320) h, the blood glucose level decreased to the minimum. This effectiveness could maintain about 2 hours. After 4 hours post administration, the blood glucose became normal. When dogs were administrated in duodenal way, YSM1591 also effect 0.5 hour later. The blood glucose decreased to the lowest after about 1.5 hours(1.20 ± 0.880) h. The effectiveness could sustain about 2.5 hours and it became normal after 4 hours later. Insulin immediately played efficacy(about 20 min) after administrated through s.c. injection and after about 1.75 hours, the glucose decreased to the lowest. This could sustained about 4 hours and became normal after 6 hours.2. The results of the pharmacokinetics in dogs showed that after the three cross dosing by oral, duodenal and subcutaneous methods, the t1/2 were separarately(0.718±0.471) h,(1.26±0.533) h and(0.772±0.200) h;the Cmax were corresponding(416±182) ?U/m L,(312±90.0) ?U/m L and(85.7±24.5) ?U/m L;the Tmax were(0.917±0.204) h?(0.5±0.000) h ?(0.444±0.0860) h; the curve area(AUC(0-t)) were(307±95.8) ?U/m L·h,(224±48.8) ?U/m L·h and(139±26.8) ?U/m L·h and the relative bioavailability were(5.51±1.96)% and(4.03±0.910)% for the oral and duodenal methods.3. The results of the transmembrane transport of YSM1591 showed that the uptake of YSM1591 was improved compared to Humulin. The concentration and administration time also affected the transport and apparent permeability coefficient(Papp) of insulin. The results showed that the amount of insulin in different samples from YSM1591 were higher than Humulin at the same concentration and time. What's more, the Papp of YSM1591 was also higher than that of the Humulin especialy at the concentration of 0.3 IU/m L and 1 IU/m L after administrated 15 min.Conclusions: The results of the transmembrane transport of insulin showed that the main way of YSM1591 transport into intestinal epithelial cells by intercellular transport. The Papp were more or less increased. What's more, the concentration and time were also effect ther transmembrane transport rate. The transport rate became slowly with time. The uptake rate could be increased by aptimising the time and dosing.The three cross experiments of pharmacokinetics and pharmacodynamics proved that YSM1591 exerted pronounced effect to decrease the blood glucose either through oral way or duodeonal way. Although the effectiveness of the oral preparation sustained a little shorter time comprared to Humulin, YSM1591 showed rapid effect in decreasing glucose level. In brief, the oral preparation YSM1591 deserved more improvemnent for its clinical utilization. |
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