In the last few years, the biopharmaceutical industries have been focusing their efforts on developing delivery systems for biomolecules, which can release different biopharmaceutical agents locally and in a sustained manner, at the same time as protecting them from degradation before reaching their target. Nowadays it is possible to deliver therapeutic dosages to selected areas of the body while side effects of a systemic dosage are minimized; that is, the concentration of the drugs at the precise sites is maintained within optimum range and under the toxicity threshold. The advances in technology allow the modification of drug release profile, adsorption, distribution, and elimination to improve the efficacy and safety, and also to tailor the treatment in response to the patient requirements.