Intradiscal drug delivery system for the treatment of low back pain.

Possible solution to the long-term control of the low back pain (LBP) would be by using an injectable pain drug carrier that can be delivered locally. The drug can be released in a controlled manner. It is also allowed to inject repeatedly more drugs percutaneously with a minimal invasion. The main objective of this study was to develop such a drug delivery system (DDS) for long-term control of discogenic LBP. The DDS consists of in situ forming hydrogel matrix (Pluronic F127 plus sodium hyaluronate) containing microspheres (MS). The solid MS were used for long-term release of the drugs. Both hydrogel matrix and MS contained a model drug, bupivacaine base (BB). The phase transition (liquid at room temperature, gel at around body temperature) could be manipulated by changing the composition of the hydrogel. In vitro test showed that approximately 3% (w/w) of the BB loaded to MS were released during 42 days, demonstrating a good potential for sustained release of bupivacaine.