Gastro Retentive Drug Delivery System

Gastro Retentive Drug Delivery System 

Session Objectives

By the end of this session, students will be able to:

       Explain various gastro-retentive strategies for drug absorption

       Elaborate various factors to be considered in the design of GRDDS

       Explain the significance of various processes involved in preformulation of GRDDS

       Formulate a suitable gastro-retentive dosage form based on the need and drug characteristics


  1. Floating Drug Delivery Systems

(a)    Non-Effervescent Systems

                                                      (i)            Colloidal Gel Barrier System (hydro dynamically balanced system)

                                                      (i)            Micro porous Compartment System

                                                    (ii)            Alginate Beads

                                                   (iii)            Hollow Microspheres / Microballons

                           (b)            Gas-Generating (Effervescent) Systems

2.       Expandable systems

3.       Bio/Muco-Adhesive Systems

4.       High-Density Systems

Classification of Gastro Retentive Drug Delivery Systems

Hydro dynamically Balanced System

Factors controlling gastric retention time of dosage

      Density of dosage form

       A density of <1.0 g. /cm3 is required to exhibit the floating  property

       Dosage forms having density lower than that of the gastric  fluids

      Size of the dosage form

       The larger the size of the dosage form, the greater will be the  gastric retention time, because the larger size would not  allow the dosage form to quickly pass through the pyloric antrum into the intestine

      Food intake, nature of the food

       Usually the presence of food increases the GRT (Gastric  retention time) of the dosage form and increases drug  absorption by allowing it to stay at the absorption site for a  longer time

      Effect of gender, posture, age

       In the upright position, the floating systems floated to the top of  the gastric contents and remained for longer time, showing  prolonged GRT

       Because of the changes in physiology with increasing age and  the hormonal responses responsible for gastric emptying, the GRT of the dosage forms may vary with the age of the individual


       Pharmacokinetic aspects

Ø  Enhanced bioavailability

Ø  Enhanced first pass biotransformation

Ø  Improved bioavailability due to reduced P-glycoprotein activity in the  duodenum

Ø  Reduces frequency of dosing

Ø  Targeted therapy for local ailments in the upper GI tract

       Pharmaco-dynamic aspects

v  Drug concentration fluctuations are reduced

v  Receptor activation selectivity is improved

v  Reduces counter-activity of the body

v  Extend time over critical (effective) concentration

v  Minimum adverse activity occurs at colon


       Gastro retentive drug delivery system is an approach to prolong gastric residence  time, thereby targeting site-specific drug release in upper gastro intestinal tract

       FDDS is considerably easy and logical approaches in development of Gastroretentive dosage forms

       HBS or Colloidal barrier systemsThese are single-unit dosage forms, containing  one or more gel-forming hydrophilic polymers

       Formulation excipients used for the GRDDS should have density < 1.0 g. /cm3

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