2006 Abstract : 2- 7

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Authors: McLaren AC*, McLaren SG, Hickmon MK

Title: Sucrose, Xylitol and Erythritol as Fillers to Increase Permeability of PMMA for Depot Delivery of Antibiotics

Addresses: UAMS Department of Orthopaedic Surgery, 4301 W. Markham Slot 644, Little Rock, AR 72205

Purpose: The purpose of this study was to measure the relative permeability of PMMA loaded with three filler materials (sucrose, xylitol, erythritol) of similar particle morphology and one material (erythritol) of half the solubility

Methods:
Palacos (PMMA) was loaded per batch with 1000 mg phenolphthalein and 28 grams of one of the fillers and made into 7 mm beads using silicone molds. 1000 mg of sodium hydroxide (NaOH) was dissolved in one litre of distilled water and used as a solution (pH =11.2) to soak the beads. Four groups of five beads each were submerged in 20 mls of the NaOH solution. The beads and the fluid turned magenta each day as the NaOH solution cam in contact withthe penolphthalein in the PMMA. The total volume of solution was exchanged daily. On days1, 2,3,5,7,10,15, 25, and 30, spectrophotometric light absorption was measured On days 1, 2, 5, 10, and 15, two beads were surface dried and split in half. The split surface of the beads was digitally photographed and the observed magenta ring caused by the NaOH solution contacting the phenolphthalein as it penetrated the bead was measured.

Results: Sucrose, xylitol, and erythritol had similar bead permeability with complete penetration to the center of the bead at 15 days. The xylitol filler led to greater colorizluid at all time periods p=.001

Discussion: All three filler materials led to similar permeability in spite of erythratol having half the solubility. The magenta color in the fluid represents elution of phenolphthalein. Xylitol filler led to greater elution of phenolphthalein than sucrose and erythitol.