Pharmaceutics & Novel Drug Delivery Systems

Oral Drug Delivery Systems

Oral route is one of the most extensively  used routes of drug administration because  of its obvious advantages of ease  of administration, improved patient compliance,  and convenience. In immediate  release (IR) dosage forms, there is little  or no control over release of drug from  the dosage form, which most often results  in constantly changing, unpredictable,  and often sub- or supra- therapeutic  plasma concentration. Modified  release (MR) dosage form refers to a  dosage form for which the drug-release  characteristics of time course and/or location  are chosen to accomplish therapeutic  or convenience objectives not offered  by conventional dosage forms.  Extended release (ER) and delayed release  (DR) dosage forms are two types of  MR dosage forms.  

ER dosage forms are formulated to make  the drug available over an extended period  after ingestion. This allows a reduction  in dosage frequency compared to the  drug presented as a conventional dosage  form (e.g., an IR dosage form). These  products typically provide numerous benefits,  including greater effectiveness in  the treatment of chronic conditions, reduced  side effects, greater convenience,  and higher levels of patient compliance  due to a simplified dosing schedule. The  term controlled release (CR) and extended  release are often used interchangeably.  A number of design options are available  to control or modulate the drug  release from a dosage form. Majority of  the oral dosage forms fall in the category  of matrix, reservoir, osmotic systems,  or ion exchange resins. DR dosage forms  release the drug at a time other than immediately  following oral administration.