Evaluation of Insulin Lispro Pharmacokinetics and Pharmacodynamics Over 10 Days of Continuous Insulin Infusion in People With Type 1 Diabetes.

BACKGROUND: We evaluated the effect of meloxicam on insulin lispro pharmacokinetics and glucose pharmacodynamics over 10 days of continuous subcutaneous insulin infusion (CSII) at one infusion site in people with type 1 diabetes (T1D). METHOD: This phase 1, randomized, double-blind, single-center, two-way crossover study enrolled adults with T1D for ≥1 year on stable CSII for ≥3 months. Participants randomly received U100 insulin lispro and LY900027 (U100 insulin lispro + 0.25 mg/mL meloxicam). Primary end points were area under the insulin lispro curve from 0 to 5 hours (AUCIns.0-5h) after bolus administration prior to a mixed-meal tolerance test (MMTT) and maximum observed concentration of insulin lispro (CIns.max) on days 5, 7, and 10, versus day 3 (baseline). RESULTS: A total of 20 participants were randomized. Insulin absorption was accelerated for insulin lispro and LY900027 from days 1 to 7. The AUCIns.0-5h was significantly lower on day 10 versus day 3 for LY900027 (-19%) and insulin lispro (-14%); the AUCIns.0-5h did not differ significantly between treatments. The CIns.max increased with LY900027 and insulin lispro (by ~14%-23% and ~16%-51%) on days 5, 7, and 10 versus day 3. The CIns.max of LY900027 was ~14%-23% lower than insulin lispro CIns.max on days 7 and 10 (P ≤ .0805). Accelerated insulin absorption and a modest loss of total insulin exposure led to a loss of MMTT glycemic control at later time points. CONCLUSIONS: The pharmacokinetics of insulin changed over catheter wear time even when an anti-inflammatory agent was present. Postprandial glycemic control was adversely affected by the accelerated insulin absorption and decreased insulin exposure.

Development of poly(lactide-co-glycolide) microparticles for sustained delivery of meloxicam.

Poly(lactide-co-glycolide) (PLGA) polymers have been widely used for drug delivery due to their biodegradability and biocompatibility. One of the objectives of encapsulating a drug in PLGA microparticles (MPs) is to achieve an extended supply of the drug through sustained release, which can range from weeks to months. Focusing on the applications needing a relatively short-term delivery, we investigated formulation strategies to achieve a drug release from PLGA MPs for two weeks, using meloxicam as a model compound. PLGA MPs produced by the traditional oil/water (O/W) single emulsion method showed only an initial burst release with minimal increase in later-phase drug release. Alternatively, encapsulating meloxicam as solid helped reduce the initial burst release. The inclusion of magnesium hydroxide [Mg(OH)2] enhanced later-phase drug release by neutralizing the developing acidity that limited the drug dissolution. The variation of solid meloxicam and Mg(OH)2 quantities allowed for flexible control of meloxicam release, yielding MPs with distinct in vitro release kinetics. When subcutaneously injected into rats, the MPs with relatively slow in vitro drug release kinetics showed in vivo drug absorption profiles consistent with in vitro trend. However, the MPs that rapidly released meloxicam showed an attenuated in vivo absorption, suggesting premature precipitation of fast-released meloxicam. In summary, this study demonstrated the feasibility of controlling drug release from the PLGA MPs over weeks based on the physical state of the encapsulated drug and the inclusion of Mg(OH)2 to neutralize the microenvironmental pH of the MPs.

Development of hot-melt extruded drug/polymer matrices for sustained delivery of meloxicam.

For effective resolution of regional subacute inflammation and prevention of biofouling formation, we have developed a polymeric implant that can release meloxicam, a selective cyclooxygenase (COX)-2 inhibitor, in a sustained manner. Meloxicam-loaded polymer matrices were produced by hot-melt extrusion, with commercially available biocompatible polymers, poly(ε-caprolactone) (PCL), poly(lactide-co-glycolide) (PLGA), and poly(ethylene vinyl acetate) (EVA). PLGA and EVA had a limited control over the drug release rate partly due to the acidic microenvironment and hydrophobicity, respectively. PCL allowed for sustained release of meloxicam over two weeks and was used as a carrier of meloxicam. Solid-state and image analyses indicated that the PCL matrices encapsulated meloxicam in crystalline clusters, which dissolved in aqueous medium and generated pores for subsequent drug release. The subcutaneously implanted meloxicam-loaded PCL matrices in rats showed pharmacokinetic profiles consistent with their in vitro release kinetics, where higher drug loading led to faster drug release. This study finds that the choice of polymer platform is crucial to continuous release of meloxicam and the drug release rate can be controlled by the amount of drug loaded in the polymer matrices.

Engineering microenvironment of biodegradable polyester systems for drug stability and release control.

Polymeric systems made of poly(lactic acid) or poly(lactic-co-glycolic acid) are widely used for long-term delivery of small and large molecules. The advantages of poly(lactic acid)/poly(lactic-co-glycolic acid) systems include biodegradability, safety and a long history of use in US FDA-approved products. However, as drugs delivered by the polymeric systems and their applications become more diverse, the significance of microenvironment change of degrading systems on long-term drug stability and release kinetics has gained renewed attention. In this review, we discuss various issues experienced with acidifying microenvironment of biodegradable polymer systems and approaches to overcome the detrimental effects of polymer degradation on drug stability and release control.

Insulin, Not the Preservative m-cresol, Instigates Loss of Infusion Site Patency Over Extended Durations of CSII in Diabetic Swine.

Insulin infusion sets worn for more than 4-5 days have been associated with a greater risk of unexplained hyperglycemia, a phenomenon that has been hypothesized to be caused by an inflammatory response to preservatives such as m-cresol and phenol. In this cross-over study in diabetic swine, we examined the role of the preservative m-cresol in inflammation and changes in infusion site patency. Insulin pharmacokinetics (PK) and glucose pharmacodynamics (PD) were measured on delivery of a bolus of regular human insulin U-100 (U-100R), formulated with or without 2.5 mg/mL m-cresol, to fasted swine following 0, 3, 5, 7, and 10 days of continuous subcutaneous insulin infusion (CSII). In a subsequent study with the same animals, biopsies were evaluated from swine wearing infusion sets infusing nothing, saline, or U-100R either with or without 2.5 mg/mL m-cresol, following 3, 7, and 10 days of CSII. Exposure to m-cresol did not impact any PK or PD endpoints. PK and PD responses dropped markedly from Days 7-10, regardless of the presence of m-cresol. Histopathology results suggest an additive inflammatory response to both the infusion set and the insulin protein itself, peaking at Day 7 and remaining stable beyond.

Reduced Silent Occlusions with a Novel Catheter Infusion Set (BD FlowSmart): Results from Two Open-Label Comparative Studies.

BACKGROUND: Insulin pump users experience periods of unexplained hyperglycemia. In some cases these may be due to insulin flow interruptions termed "silent occlusions," which occur without activating the pump alarm and may require set replacement. MATERIALS AND METHODS: In-line pressure profiles of a novel infusion set with a 6-mm, 28-gauge polymer, dual-ported catheter (BD FlowSmart™; Becton Dickinson and Co., Franklin Lakes, NJ) were compared with those of an existing infusion set (Quick-set®; Medtronic MiniMed, Northridge, CA) in two separate studies involving insulin diluent infusions over 2.5-4.5-h periods in healthy adults without diabetes. Study 1, a pilot study (n = 25), compared the occurrence of flow interruption events (silent occlusions and/or occlusion alarms) between the two infusion sets and between manual or device-assisted insertion methods. Study 2 (n = 60) was designed to show ≥50% reduction in flow interruption events with the BD set after manual insertions. (Silent occlusions were defined by a continuous pressure rise for ≥30 min.) RESULTS: In Study 1, significantly fewer silent occlusions were seen with BD FlowSmart versus Quick-set infusion sets for both manual (three of 22 [13.6%] vs. 12 of 24 [50%]; P = 0.012) and mechanical (two of 24 [8.3%] vs. nine of 25 [36%]; P = 0.037) insertions, yielding risk reductions of 73% (95% confidence interval [CI], 25-91%) and 77% (95% CI, 17-94%), respectively. In Study 2, flow interruption events occurred in three of 117 (2.6%) and 12 of 118 (10.2%) BD FlowSmart and Quick-set infusion sets, respectively, yielding a 75% risk reduction (95% CI, 20-92%; P = 0.030). Percentage of time with flow interruption was significantly lower with BD sets in both studies (P < 0.02). Leakage (>0.5 IU or 5 µL) occurred infrequently and did not differ between sets. CONCLUSIONS: A novel side-ported insulin infusion set demonstrated significant reductions in flow interruptions, including silent occlusions, versus a leading marketed set, which may improve insulin delivery.