Hyaluronic acid in Pluronic F-127/F-108 hydrogels for postoperative pain in arthroplasties: Influence on physico-chemical properties and structural requirements for sustained drug-release.

In this study, we reported the hyaluronic acid (HA) on supramolecular structure of Pluronic F-127 (PLF-127) and/or Pluronic F-108 (PLF-127) hydrogels, as well as their effects on release mechanisms, looking forward their application as lidocaine (LDC) drug-delivery systems in arthroplastic surgeries. We have studied the HA-micelle interaction using Dynamic Light Scattering (DLS), the micellization and sol-gel transition processes by Differential Scanning Calorimetry (DSC) and Rheology., of PL-based hydrogels and. The presence of HA provided the formation of larger micellar dimensions from ~26.0 to 42.4nm. The incorporation of HA did not change the micellization temperatures and stabilized hydrogels rheological properties (G'>G″), showing no interference on PL-thermoreversible properties. Small-Angle-X-ray Scattering (SAXS) patterns revealed that HA incorporation effects were pronounced for PLF-127 and PLF-108 systems, showing transitions from lamellar to hexagonal phase organization (HA-PLF-127) and structural changes from cubic to gyroid and/or cubic to lamellar. The HA insertion effects were also observed on drug release profiles, since lower LDC release constants (Krel=0.24-0.41mM·h-1) were observed for HA-PLF-127, that presented a hexagonal phase organization. Furthermore, the HA-PL systems presented reduced in vitro cytotoxic effects, pointed out their tendency to self-assembly and possible application as drug delivery systems.

Inclusion complex of S(-) bupivacaine and 2-hydroxypropyl-beta-cyclodextrin: study of morphology and cytotoxicity

Local anesthetics (LA) belong to a class of pharmacological compounds that attenuate or eliminate pain by binding to the sodium channel of excitable membranes, blocking the influx of sodium ions and the propagation of the nerve impulse. S (-) bupivacaine (S(-)bvc) is a local anesthetic of amino-amide type, widely used in surgery and obstetrics for sustained peripheraland central nerve blockade. This article focuses on the characterization of an inclusion complex of S(-) bvc in2-hydroxypropyl- beta-cyclodextrin (HP-beta -CD). Differential scanning calorimetry, scanning electron microscopy andX-Ray diffraction analysis showed structural changes inthe complex. In preliminary toxicity studies, the cellviability tests revealed that the inclusion complex decreased the toxic effect (p smaller that 0.001) produced by S(-) bvc.These results suggest that the S(-) bvc:HP- beta-CD inclusion complex represents a promising agent for the treatment of regional pain.