Pasty polymers in cancer drug therapy

Injectable polymeric systems suitable for the localized delivery of anticancer agents are reviewed. These polymeric systems include: drug-loaded low melting temperature polymers that are injected at the melting temperature of the polymer, usually below 50-°C, that solidify at body temperature to form an in situ device; polymer solutions in buffer or in N-methyl pyrrolidone, ethanol, or acetate esters which, upon injection in tissue,are absorbed into the tissue and cause precipitation of the polymer at the injection site; in situ crosslinking of polymer solutions to form a polymeric implant; and thermoresponsive polymer solutions that are soluble at room temperature and solidify at body temperature. However, these systems are hydrophilic and suffer from burst release of drug within a few hours post injection. Hydrophobic injectable, pasty, fat-based polymers that gel when injected in tissue have been used for the extended release of paclitaxel, cisplatin, and other agents. This polymer releases the drug in a controlled manner with no burst release. These systems have a potential use as drug carriers for regional or systemic drug delivery.