Depression is a common mental disorder discerns with depressed mood, loss of interest, the primary treatment methods are drug therapy, electroconvulsive therapy, psychotherapy, light therapy, vagus nerve stimulation, etc. A number of innovative delivery systems have been developed to address suboptimal therapy outcomes by enhancing drug delivery, assuring efficacy of treatment, reducing side effects, improving compliance and drug targeting specific locations resulting in a higher efficiency. Depot delivery offers the advantage of a very high loading, controlled release of drug for an extended period of time and reduces frequency of dosing. The increase in AUC and decrease in Cmax reflects that the depot formulations could reduce the toxic complications and limitations of conventional and oral therapies. Products at preclinical and clinical stages include formulations of naltrexone and buprenorphine for alcoholism/drug abuse, GLP-1 peptides for diabetes, r-hFSH for fertility, dopamine for nerve growth, dexamethasone for ocular treatment, melanotan for cancer prevention, plasmid DNA for cancer prevention, a variety of vaccines, octreotide generics, etc. Most depot formulations are comprised of biodegradable polymer-excipients that control the rate of drug release and resorbs during/after drug release. The major advantage of depot antipsychotics over oral medication was facilitation of compliance in medication taking. One class of biodegradable polymers that has gained wide acceptance and still attractive today is lactide/ glycolide polymers. The greatest advantage of these degradable polymers is that they are broken down into biologically acceptable molecules that are metabolized and removed from the body via normal metabolic pathways. This versatile delivery system offers the advantage of a very high loading and controlled release of various drug for an extended period of time compared with plain delivery system. New formulations of depression can offer advantages over older formulations in terms of convenience, side effect profiles, efficacy, and/or a fast onset of action.