Combined effects of drugs and plasticizers on the properties of drug delivery films

Formation of scar tissue may be reduced or prevented if wounds are locally treated with a combination of molecules tuned to the different healing phases, guiding tissue regeneration along a scar free path. To this end, drug delivery devices made of cellulose acetate phthalate and Pluronic F-127 were loaded with either quercetin or pirfenidone and plasticized with either triethyl citrate or tributyl citrate. Quercetin inhibits oxidative stress, and pirfenidone has been shown to reduce production of pro-inflammatory and fibrogenic molecules. The combined effects of drug and plasticizer on erosion, release, and mechanical properties of the drug delivery films were investigated. Triethyl citrate-plasticized films containing quercetin released drug at a slower rate than did tributyl citrate films. Pirfenidone-loaded films released drug at a faster rate than erosion occurred for both types of plasticizers. Higher plasticizer contents of both triethyl citrate and tributyl citrate increased the elongation and decreased the elastic modulus. In contrast, increased pirfenidone loading in both triethyl citrate and tributyl citrate films resulted in a significantly higher modulus, an antiplasticizer effect. Adding pirfenidone significantly decreased elongation for all film types, but quercetin-loaded samples had significantly greater elongation with increasing drug content. Films containing quercetin elongated more than did pirfenidone-loaded films. Quercetin is over 1.5 times larger than pirfenidone, has water solubility over 12 times lower, and has 6 times more bonding sites than pirfenidone. These differences affected how the two drugs interacted with cellulose acetate phthalate and Pluronic F-127 and thereby determined polymer properties. Drug release, erosion, and mechanical properties of association polymer films can be tailored by the characteristics of the drugs and plasticizers included in the system.