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5:44 kB/s0 Ye.il o.il 51% DOC-20240827-WA... Microscopic drug reservoir Polymer matrix...

5:44 kB/s0 Ye.il o.il 51% DOC-20240827-WA... Microscopic drug reservoir Polymer matrix Fig. 3.14: Micro Reservoir Dissolution Controlled TDDS GASTRO-RETENTIVE DRUG DELIVERY SYSTEMS| 3.10 INTRODUCTION Gastro-Retentive Drug Delivery System (GRDDS) has gained immense popularity in the field of oral drug delivery recently. It is a widely employed approach to retain the dosage form in the stomach for an extended period of time and release the drug slowly that can address many challenges associated with conventional oral delivery. including poor bioavailability. Different innovative approaches like magnetic field assisted gastro-retention, plug type sweling system, muco-adhesion technique, floating system with or without effervescence are being applied to fabricate GRDDS. Novel Drug Delivery Systems 3.19 Transdermal Drug Delivery Systems Gastro-retentive drug delivery is an approach to prolong gastric residence time, thereby targeting site-specific drug release in the upper gastrointestinal tract (GIT) for local or systemic efects. These drug delivery systems suffer from mainly two adversities: the short gastric retention time (GRT) and unpredictable short gastric emptying time (GET), which can result in incomplete drug release from the dosage form in the absorption zone (stomach or upper part of small intestine) leading to diminished efficacy of administered dose. To formulate a site-specific orally administered controlled release dosage form, it is desirable to achieve a prolong gastric residence time by the drug delivery. Prolonged gastric retention improves bioavailability, increases the duration of drug release, reduces drug waste, and improves the drugs that are less soluble in a high pH environment. Also prolonged gastric retention time (GRT) in the stomach could be advantageous for local action in the upper part of the small intestinee.g. treatment of peptic ulcer, etc. 3.10.1 Advantages of GRDDS 1. Enhanced bio-availability. 2. Reduced frequency of dosing. 3. Targeted therapy for local ailments in the upper GIT. 4. Patient compliance. 5. Improved therapeutic efficacy. Gastro-retentive drug delivery system (GRDDS) greatly improves pharmacotherapy of the stomach through local drug release leading to high drug concentrations at gastric mucosa (eradicating helicobacter pylori from the sub-mucosal tissue of the stomach), making it possible to treat stomach and duodenal ulcers, gastritis and esophagitis, reduce the risk nf gastric carcinoma, controlled release antacid formulations. GRDDs can be used as car drugs which are absorbed from absorption windows in stomach. For example, antibiotics, antiviral and antifungal agents etc. (sulphonamides, quinolones, cephalosporins, aminoglycosides and tetracyclines, etc) are taken up only from very sites of the GI mucosa. 3.10.2 Disadvantages of GRDDS There are certain situations where castric retention is not cdesirable. Aspirin and non Növel Drug Delivery Systems 3.20 2. 3. Requires the presence of food to Transdermal Drug Delivery Systems Drugs, which undergo delay gastric significant first passemptying. may 4 candidates for floating drug May lead to alter systemic delivery system sincemetabolism, the slow gastric not be desirable 5. Drugs having solubility or bioavailability. emptying. or which are irritants to stability problems in the highly 3.10.3 Factors gastric mucosa cannot be acidic gastric (a) Density of Controlling Gastric formulated as GRDDS. environment Dosage Form: Dosage forms having a density Retention of Dosage Forms behaviour and hence gastric lower than that of gastric A density of