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Sustained release's definition is more akin to a "controlled release" rather than "sustained". Extended-release dosage consists of either sustained-release (SR) or controlled-release (CR) 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 ...
Controlled or modified-release formulations alter the rate and timing at which a drug is liberated, in order to produce adequate or sustained drug concentrations. [28] The first controlled-release (CR) formulation that was developed was Dexedrine in the 1950s. [13]
In other sustained release formulations the matrix swells to form a gel through which the drug exits. Another method by which sustained release is achieved is through an osmotic controlled-release oral delivery system, where the active compound is encased in a water-permeable membrane with a laser drilled hole at one end. As water passes ...
The first drug delivery system is often dated to the 1950s, when Smith Kline & French Laboratories introduced the Spansule technology. [2] Between 1950s and 1980s, there were four drug release systems developed for oral and transdermal applications: dissolution, diffusion, osmosis, and ion-exchange controlled release. [3]
The drug is expelled via the laser-drilled hole visible on the left side of the tablet. The osmotic-controlled release oral delivery system (OROS) is an advanced controlled release oral drug delivery system in the form of a rigid tablet with a semi-permeable outer membrane and one or more small laser drilled holes in it.
The concept of stimuli-responsive drug delivery systems can actually be seen as ahead of this time, since the first pH-responsive drug coating was used in the late 1950s in Europe. [4] These coatings were used on drugs delivered to the stomach, so that they would protonate and dissolve at low pH to release drug. [4]
An advantage of a transdermal drug delivery route over other types of medication delivery (such as oral, topical, intravenous, or intramuscular) is that the patch provides a controlled release of the medication into the patient, usually through either a porous membrane covering a reservoir of medication or through body heat melting thin layers ...
Drug carriers are primarily used to control the release of drugs into systemic circulation. This can be accomplished either by slow release of a particular drug over a long period of time (typically diffusion ) or by triggered release at the drug's target by some stimulus, such as changes in pH, application of heat, and activation by light.