Metals as Dual-function Matrices for Sustained Release of Drugs

Sustained release of drugs is a major, well developed field of biomaterials. In our research we have developed methods for the entrapment of various drugs and bioactive compounds within silver and platinum. Generally, the entrapment process involves a carefully developed procedure for reducing the metal cation in the presence of the dissolved drug, which results in the entrapment of the drug inside the bulk of aggregated metal.

The motivation to entrap bioactive materials within silver has been to create dual-functional composites for wound treatment, that is, control of microbial contamination, emanating from the antimicrobial activity of silver, and providing at the same time pain relief capabilities due to the entrapped pain killers. We have successfully entrapped ibuprofen and naproxen (two NSAIDs), tramadol (an opioid) and bupivacaine (an LA) within silver, resulting in drug@Ag composites. Upon exposure of the resulting composites to water, controlled release of the drugs from the composite occurs while silver ions are released from the bulk metal and create an antiseptic activity, the efficacy of which was proven against Pseudomonas aeruginosa.

Platinum was selected as an additional matrix mainly due to its low toxicity towards mammalian cells, which promotes its wide use for a variety of implant applications. The new composites therefore can be used as a matrix for sustained release of drugs needed after implantation, such as for post-operative infection control, for pain management and for anticoagulation activity. Successful entrapments of two types of NSAID’s - ibuprofen and naproxen, of an antibacterial agent – chlorohexidine, and of antibiotics - were achieved.