Gastro retentive Flashcards
What is GRDDS
an approach to prolong gastric residence time,
targeting site-specific drug release in the upper gastrointestinal tract (GIT) for local or
systemic effects.
Remain in the gastric region for long periods and hence significantly prolong the gastric retention time (GRT) of drugs.
Advantages of Gastroretentive
-Reduces dosing frequency for drugs with short half-life, improving patient compliance.
-Provides targeted therapy for local treatments.
-Reduces fluctuations in drug concentration, reducing concentration-dependent side effects.
-Enhances bioavailability compared to conventional controlled release formulations.
Factors controlling gastric
retention of dosage forms 8
➢ Density of dosage forms
➢ Size and shape
➢ Food intake and its nature (generally prolong gastric retention)
➢ Gender (female>male)
➢ Posture (depend on the dosage form)
➢ Age (elderly>young)
➢ Concomitant drug administration (i.e. opiate, cisapride..)
➢ Disease state (i.e. hypothyroidism or hyperthyroidism..)
Types of drug Candidates for GRDD 4
-Acting locally in the stomach: Amoxicillin, sucralfate and clarithromycin
-Narrow absorption Window: Ranitidine, riboflavin, theophylline, levodopa, furosemide, ciprofloxacin
-Degraded in intestinal fluid: Captopril
-Poorly soluble in intestine: Diazepam and verapamil HCl
Drugs unsuitable for GRDDS 3
➢ Drugs that have solubility problems in stomach (e.g. phenytoin).
➢ Drugs which are irritant to gastric mucosa
➢ Drugs that are unstable in the acidic environment of the stomach (e.g. erythromycin).
Classification of GRDDS 5
- High density systems
- Low density systems
- Expandable systems
- Mucoadhesive systems
- Magnetic system
High density (sinking) systems
Addesh el density?
e.g. of heavy intert material
a density within the range of 2.4-2.8 g/cm³
Able to withstand the movements of gastric peristalsis
accomplished by incorporating heavy inert materials such as zinc oxide, titanium dioxide,
barium sulphate or iron powder
Low density (floating) system
bulk density?
Do they affect gastric emptying
How is the drug released
What are the two types of systems involved?
a bulk density less then
gastric fluids (1.004-1.01 g/cm³)
so remain buoyant in the stomach
without affecting gastric emptying rate
for a prolonged period
the drug is released slowly from the system
They are divided into:
A. Non-effervescent systems
B. Effervescent/gas generating systems
Non-Effervescent systems
fi kmn 2 types
Hydrodynamically Balance Systems
Inherent Low Density Systems
Hydrodynamically balanced systems
They attain a low density (less than
1g/cm3) by swelling in gastric fluids
maintains its integrity and low density for a
predetermined period of time.
drug is released by
controlled diffusion through the
polymeric gel barrier.
Hydrodynamically balanced systems most used polymer?
Hydroxypropyl methylcellulose (HPMC)
Inherent low density systems
What are e.g. of low density material?
What is the advantage?
Floating is achieved by incorporation of low-density
materials, such as fatty substances, foam powder
(polypropylene), or by formulating porous and hollow systems.
provide immediate floating, thereby preventing the
risk of premature gastric emptying. (advabntagw)
Review el images bl lecture
Effervescent/gas generating systems: 2 types
Inflatable floating systems
Effervescent systems
Inflatable floating systems
Consists of shu? containg shu? which produces shu?
consist of inflatable chamber containing
volatile liquids which produce
gas at body temperature,
thereby initiating floating.
Inflatable floating systems image
Capsule = gelatin
Bioerodible polymer film = polylactic, polyanhydride
Inflatable chamber = organic liquid (ether) becomes gas at body temp
Drug reservoir is found on surface of chamber
