Sustained Release Drug Delivery System (SRDDS) is 
designed to release a drug at a predetermined rate by 
maintaining a constant drug level for a specific period of 
time with minimum side effects. Now a day’s focus on the 
development of SRDDS has increased, as very few drugs 
are coming out of research and development and already 
existing drugs are suffering the problem of resistance due 
to their irrational use specifically in case of drugs like 
antibiotics. The major goal of designing SR formulations 
was intended to modify and improve the drug performance 
by increasing the duration of drug action, decrease the 
dosing frequency, reduced side effects, decreasing the 
required dose employed and providing the shortest 
possible time by using smallest quantity of drug 
administered by the most suitable route. SR dosage forms 
are designed to transport the blood level of a drug instantly 
to therapeutic concentrations by means of an initial dose 
portion and then maintain this level for a certain 
predetermined time with the continuation portion. SR of 
drugs in GI tract following oral administration is not 
affected by the absorption process. The major goal of SR 
dosage forms is the improvement of drug therapy assessed 
by the relationship between advantages and disadvantages 
of the use of SR systems. The present review article is 
useful in knowledge of highlighted formulation 
approaches, criteria for drug selection, different countries  sustained release dosage form patents and advance novel 
research for SRDDS. The present review is concerned with 
the patent study of drug release through controlled or 
sustained release dosage forms. This patent review is useful 
in knowledge of sustained release dosage forms for its 
application.