Rheological and Drug Delivery Characteristics of Poloxamer-Based Diclofenac Sodium Formulations for Chronic Wound Site Analgesia

Chronic wounds are a significant and growing health problem, and clinical treatment is often a painful experience. A topical dosage form would be optimal to treat this pain. Poloxamer 407, a thermosensitive polymer that is a liquid at low temperatures but gels at higher temperatures, is well suited to administer topical analgesics to chronic wound sites. The goal of this study was to evaluate the gelation and drug delivery properties of poloxamer 407 gels containing diclofenac sodium for potential use in chronic wound analgesic delivery. The gelation properties of poloxamer formulations were evaluated rheologically. Drug delivery properties of poloxamers loaded with diclofenac sodium were evaluated using snakeskin dialysis membranes, intact porcine ear skin, and porcine ear skin impaired via tape stripping. A commercial gel product and a solution of diclofenac sodium in water were used as control formulations. Poloxamer concentration and gelation temperature varied inversely, and the addition of higher concentrations of diclofenac sodium correlated to significant increases in poloxamer gelation temperature. Poloxamer solutions were effective in limiting the permeation of diclofenac sodium through membranes with impaired barrier properties, and delivery of diclofenac sodium from poloxamer 407 did not vary significantly from delivery observed from the commercial gel product. The amount of drug delivered in 24 h did not change significantly with changes in poloxamer 407 concentration. The results of this study indicate that poloxamer 407 may be a useful formulation component for administration of an analgesic product to a chronic wound site.