page_title: Modified-release dosage
section_title: Osmotic systems
hierarchical_section_title: Modified-release dosage / Methods / Osmotic systems
caption_attribution_description: English: A 54mg tablet of Concerta, which uses OROS technology. 22% of the drug is contained in the red overcoat, while the remaining 78% is split between two drug layers of differing concentration. The tablet uses an additional push layer that expands as water enters the tablet via the osmotic membrane. The drug is expelled via the laser-drilled hole visible on the left side of the tablet.
context_page_description: Modified-release dosage is a mechanism that delivers a drug with a delay after its administration or for a prolonged period of time or to a specific target in the body.
  Sustained-release dosage forms are dosage forms designed to release a drug at a predetermined rate in order to maintain a constant drug concentration for a specific period of time with minimum side effects. This can be achieved through a variety of formulations, including liposomes and drug-polymer conjugates. Sustained release's definition is more akin to a "controlled release" rather than "sustained".
  Extended-release dosage consists of either sustained-release or controlled-release dosage. SR maintains drug release over a sustained period but not at a constant rate. CR maintains drug release over a sustained period at a nearly constant rate.
  Sometimes these and other terms are treated as synonyms, but the United States Food and Drug Administration has in fact defined most of these as different concepts. Sometimes the term "depot tablet" is used by non-native speakers, but this is not found in any English dictionaries and is a literal translation of the term used in Swedish and some other languages.
context_section_description: Osmotic controlled-release oral delivery systems (OROS) have the form of a rigid tablet with a semi-permeable outer membrane and one or more small laser drilled holes in it. As the tablet passes through the body, water is absorbed through the semipermeable membrane via osmosis, and the resulting osmotic pressure is used to push the active drug through the opening(s) in the tablet. OROS is a trademarked name owned by ALZA Corporation, which pioneered the use of osmotic pumps for oral drug delivery.
  Osmotic release systems have a number of major advantages over other controlled-release mechanisms. They are significantly less affected by factors such as pH, food intake, GI motility, and differing intestinal environments. Using an osmotic pump to deliver drugs has additional inherent advantages regarding control over drug delivery rates. This allows for much more precise drug delivery over an extended period of time, which results in much more predictable pharmacokinetics. However, osmotic release systems are relatively complicated, somewhat difficult to manufacture, and may cause irritation or even blockage of the GI tract due to prolonged release of irritating drugs from the non-deformable tablet.
caption: A 54mg tablet of Concerta, which uses OROS technology.
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