Dexamethasone Delivery by an Implant-Mediated Drug Delivery System in the Canine Mandible

Release pattern of dexamethasone after administration through an implant-mediated drug delivery device with an active plunger of super absorbent polymer

The implant-mediated drug delivery system (IMDDS) is a novel, innovative device that allows drug delivery through bone marrow. The purpose of this study was to investigate the effect of an active plunger component made of super absorbent polymer (SAP) on the plasma concentration of dexamethasone released from the IMDDS. The IMDDSs were installed in a total of 18 rabbits. After complete healing, dexamethasone was loaded with the SAP active plunger and with water to cause expansion in the test group (n = 9), while only the drug was loaded in the control group, as per the original protocol (n = 9). The release patterns of each group were monitored for 2 weeks by measuring the plasma concentration of the drug. Both groups showed sustained release of drug. However, the test groups showed more rapid increase in plasma concentration and higher area under the curve (AUC) throughout the observation period. The incorporation of a SAP active plunger component in the IMDDS resulted in an increase in initial release of drug and higher bioavailability within the observation period of 2 weeks after dexamethasone administration.

Plasma concentration of metformin and dexamethasone after administration through Osseogate

BACKGROUND

Osseogate is a novel drug delivery route through bone marrow involving a modified implant used as the drug delivery system. The purpose of this study was to evaluate the effects of individual drug physicochemical characteristics on the pharmacokinetic behavior when using the Osseogate as administration route.

METHODS

Implant-mediated drug delivery systems (IMDDS) were installed in a total of 18 rabbits. After complete healing, water-soluble metformin hydrochloride was administered to one group (n = 9) while poorly soluble dexamethasone was administered to the other group (n = 9). The release patterns of each group were monitored for two weeks by measuring the plasma concentration of each drug.

RESULTS

Both groups showed relative sustained release. However, metformin hydrochloride showed more rapid diffusion and early termination of drug release compared with dexamethasone.

CONCLUSIONS

The physicochemical properties of drugs significantly affected the release pattern through Osseogate. Further research is required to achieve controlled delivery using this route.

Novel route of insulin delivery using an implant-mediated drug delivery system

Patients with diabetes mellitus (DM) frequently require multiple painful injections of insulin to manage their blood glucose level. A newly introduced, modified titanium implant, the implant-mediated drug delivery system (IMDDS), has the advantage of sustained, needle-free drug delivery. We evaluated the feasibility of the IMDDS as an alternative route of insulin delivery in an alloxan-induced rabbit DM model. Among a total of 30 rabbits with IMDDSs, 25 survived the induction and had a blood glucose level (BGL) higher than 300 mg/dl. The animals were divided into two groups: 13 in the test group to which insulin was administered via the IMDDS and 12 in the untreated control group. The BGL was monitored and measured at 0, 2, 4, 6, 8, 12, and 24 hours on the first day and every 12 hours thereafter for a total of 2 weeks. Marked hypoglycemic effects of insulin in the test rabbits were detected from the 2-h time point, and the mean BGL fell below the normal range from 12 h after insulin administration via the IMDDS. The effects lasted the entire 2-week period. Control rabbits did not show a pronounced decrease in BGL except for three animals who exhibited spontaneous recovery. The mean body weight of the test group was significantly higher than that of the control group at the end of the observation period. Although this implant requires several improvements, the IMDDS exhibited promise as an alternative route of insulin delivery with the advantages of being a sustained, needle-free insulin delivery system.