Gastrointestinal tract, controlled-release

AQP7 is expressed in the proximal tubule of the kidney, testis, gastrointestinal tract, immature dendritic cells and ear. This glycerol channel is also highly expressed in adipocytes where it is thought to control the release of triglycerides. 

New routes of administration transmucosal specific regional uptake in gastrointestinal tract New pattern of drug release bolus/flrst order/pulsatile feedback control disease-related release of drug... 

Inorganic compounds such as aluminium hydroxide, sodium bicarbonate, and magnesium and calcium carbonates are commonly used as antacids. There is much scope for the redesign of these agents to achieve fine control of local pH values in the gastrointestinal tract via control of the rate of release of the active bases (e.g., from insoluble compounds). 

The direct transport of absorbed drugs into systemic circulation, effectively by-passing the first-pass effect of the liver and gastrointestinal tract Lower enzymatic activity compared to the gastrointestinal tract or liver Amenability to self-medication, which increases patient compliance Possibility of pulsatile delivery of some drugs to simulate the biorhythmic release of these drugs Lower risk of overdosage Achievement of controlled release... 

Yeh, P.Y., Berenson, M.M., Samowitz, W.S., Kopeckova, P, and Kopecek, J. (1995). Site-specific drug-delivery and penetration enhancement in the gastrointestinal-tract. J. Control. Release, 36, 109-124. 

Numerous cases exist in the pharmaceutical field in which pH control of drug delivery may be beneficial. For example, the ability to store a drug molecule in the dry state in a polymer, to be released when the polymer reaches a region in the gastrointestinal tract that is characterized by a certain pH range (acidic in stomach, alkaline in the small intestine) has prompted a number of researchers to study pH-sensitive polymer gels as potential drug carriers for oral delivery [1-4]. 

Dosages and routes of administration Morphine is available in different salt forms but the hydrochloride and sulfate (Vermeire and Remon, 1999) are used preferentially. The compound can be administered by the oral, parenteral or intraspinal route. Oral application is preferred for chronic pain treatment and various slow release forms have been developed to reduce the administration frequency to 2-3 times per day (Bourke et al., 2000). Parenteral morphine is used in intravenous or intramuscular doses of 10 mg, mostly for postoperative pain and self-administration devices are available for patient-controlled analgesia (PCA). Morphine is additionally used for intraspinal (epidural or intrathecal) administration. Morphine is absorbed reasonably well in the lower gastrointestinal tract and can be given as suppositories. 

Poor absorption of many drugs in the lower gastrointestinal (GI) tract necessitates controlled release dosage forms to be maintained in the upper GI tract, particularly the stomach and upper small intestine.1 7... 

Asmussen, B., Cremer, K., Hoffman, H., et al. Expandable gastroretentive therapeutic system with controlled active substance release in the gastrointestinal tract, U.S. Patent 6,290,989, 2001. 

Oral Gastrointestinal tract Oral dosage forms controlled release... 

Ion exchange can be an effective method for the controlled release of ionizable drugs that are coupled with the oppositely charged ionic groups on a polymer matrix, as in ion-exchange resins used in gastrointestinal (Gl) applications. The drug release from such a system depends on the ionic environment, that is, pH and electrolyte concentration within the Gl tract, as well as the properties of the resin (5). 

Nasal administration. Apart from parenteral administration, controlled release dosage forms based upon the microsphere concept should have application to other routes of administration. Microspheres in the form of pellets have been used to deliver drugs to the gastrointestinal tract and other examples include the administration of microspheres to the eye and topically to the lungs. In recent studies Ilium (20) has employed microspheres as possible controlled release formulations for nasal application. Such studies have relevance to the delivery of novel macromolecular compounds such as peptides and proteins. 

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