NEW ANTIINFECTIOUS BIOMATERIALS - CIPROFLOXACIN CONTAINING POLYURETHANES AS POTENTIAL-DRUG DELIVERY SYSTEMS TO PREVENT FOREIGN-BODY INFECTIONS

Device related infections are an increasing problem since foreign mate rials are used in modern medicine; Ciprofloxacin-HCl salt (CAS 86393;3 2-0) and lipophilic ciprofloxacin-betaine (Bay o 9867) incorporated in to polyurethanes by solvent casting technique were studied in order to develop antiinfectious properties of this biomaterial. Drug release r ates, bacterial colonization and morphological features of the polymer -ciprofloxacin combinations were studied and the physico-chemical mech anisms of the delivery were discussed. Ciprofloxacin salt showed a fas t initial release rare, whereas ciprofloxacin-betaine was characterize d by a more continuous release behaviour. A higher diffusity of the li pophilic ciprofloxacin-betaine in the polymer could be shown as compar ed to its salt incorporated into the polyurethane. The high initial bu rst effect of the hydrochloride antibiotic was caused by its high solu bility in the elution medium. Bacterial colonization tb the antibiotic -loaded polyurethanes was inhibited effectively only by preparations s howing a slower but more sustained drug release. Scanning electron mic roscopy (SEM) demonstrated that the polyurethane-antibiotic combinatio n was most homogenous for ciprofloxacin-betaine. Polyurethane material loaded with ciprofloxacin salt showed crystals at the surface and a g ranular structure of the polymeric matrix. Crystalline structure of th e drug on polymeric surfaces varied with loading concentration and lip ophilicity. Physico-chemical similarity of the polymeric material and the antibiotics is important for the homogeneity of the polymer-antibi otic combinations. High homogeneity is required for a sustained and pr olonged release and effective inhibition of bacterial colonization.