Gastro-Retentive Drug Delivery System

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Questions and Answers

What is the primary objective of a gastro-retentive drug delivery system?

Prolonging the residence time of the drug in the stomach (correct)

Eliminating the need for oral dosage forms

Reducing the gastric pH to improve drug solubility

Increasing the drug absorption in the upper intestine

Which compartment of the stomach primarily acts as a food reservoir?

Antrum

Fundus (correct)

Pylorus

Body (correct)

How does the pylorus function in the stomach?

It primarily stores food before digestion

It generates positive pressure for food movement

It sieves processed food to prevent large objects from entering the intestine (correct)

It acts as a mixing site for gastric contents

What role does the fundus play in stomach physiology?

It generates positive pressure due to gas accumulation Signup and view all the answers

Why is gastro-retentive drug delivery ideal for treating peptic ulcers?

It ensures prolonged contact of the drug with the stomach lining Signup and view all the answers

How does the stomach contribute to food sterilization?

Through the secretion of hydrochloric acid Signup and view all the answers

What is the primary characteristic of floating drug delivery systems?

They remain buoyant in the stomach without affecting gastric emptying. Signup and view all the answers

How do non-effervescent systems achieve swelling?

By imbibition of gastric fluid and mixing with a gel former. Signup and view all the answers

What is a distinctive feature of high-density gastroretentive systems?

They sink to the bottom of the stomach for rapid release. Signup and view all the answers

What role does air trapped by swollen polymers play in drug delivery systems?

It provides buoyancy to dosage forms. Signup and view all the answers

Which of the following is NOT a type of gastroretentive drug delivery system?

Barrier methods Signup and view all the answers

What is the main feature of swelling drug delivery systems?

They utilize superporous hydrogels to achieve their effect. Signup and view all the answers

Which phase of gastric motility is characterized by strong contractions that help clear digested material from the stomach?

Phase III Signup and view all the answers

What is the primary characteristic of Phase II in the fasted state of gastric motility?

Increasing frequency and strength of contractions Signup and view all the answers

How long can gastric emptying potentially be extended in the fed state?

Up to 14 hours Signup and view all the answers

What happens to particles larger than 5 mm in diameter during gastric emptying?

They are retained in the stomach until digestion Signup and view all the answers

What is the risk associated with administering gastro-retentive drug delivery systems in the fasted state?

Risk of premature emptying during housekeeper waves Signup and view all the answers

Which statement accurately describes the emptying of liquids from the stomach?

Liquids usually empty within 30 minutes by proximal stomach contractions Signup and view all the answers

During which phase of the interdigestive myoelectric motor complex does the stomach exhibit no contractions?

Phase IV Signup and view all the answers

What is the general impact of the type and nutritional density of a meal on gastric emptying?

They can influence gastric emptying time significantly Signup and view all the answers

Which of the following factors significantly influences gastric retention of dosage forms?

Density of the dosage form Signup and view all the answers

What characteristic of drug delivery systems correlates with better residence time in the stomach?

Size greater than 7 mm Signup and view all the answers

How does food intake affect the gastric retention of dosage forms?

Viscosity and volume of fluid, along with caloric value, have a significant impact. Signup and view all the answers

Which group tends to have a slower gastric emptying rate according to the factors influencing retention?

Elderly individuals Signup and view all the answers

Which of the following types of drugs is most suitable for gastro-retentive drug delivery systems?

Drugs locally active in the stomach Signup and view all the answers

What type of drugs should generally be avoided in gastro-retentive drug delivery systems?

Drugs with very limited acid solubility Signup and view all the answers

Which of the following factors does NOT impact gastric retention of dosage forms?

Frequency of dosing Signup and view all the answers

What effect does gender have on gastric emptying rates?

Females have a slower emptying rate than males. Signup and view all the answers

What is a characteristic of the colloidal gel barrier system?

The polymer forms a hydrated boundary layer upon capsule disintegration. Signup and view all the answers

Which mechanism is employed in the microporous compartment system for drug delivery?

Continuous transportation of dissolved drug across the intestine. Signup and view all the answers

What distinguishes alginate beads in a sustained-release dosage form?

They maintain a floating force due to their porous structure. Signup and view all the answers

What is the primary function of the gas-generating system in buoyant drug delivery?

To react with gastric acids and produce carbon dioxide for floatation. Signup and view all the answers

Which factor is crucial for the performance of superporous hydrogels?

The swelling capability must rapidly exceed the emptying pressure of the stomach. Signup and view all the answers

What characterizes hollow microspheres in drug delivery?

The gas phase within contributes to their buoyancy in acidic environments. Signup and view all the answers

Which excipient is not typically associated with a hydrodynamically balanced system?

Calcium carbonate Signup and view all the answers

What is the role of sodium alginate in formulating alginate beads?

To precipitate when mixed with calcium chloride forming beads. Signup and view all the answers

In the preparation of chitosan microspheres, what method is primarily used?

Water-in-oil emulsion solvent diffusion method. Signup and view all the answers

Which of the following is a common characteristic among floating dosage forms?

They are designed to remain buoyant in gastric fluids for prolonged periods. Signup and view all the answers

Study Notes

Objectives of Gastro-Retentive Drug Delivery Systems

Prolongs residence time of oral dosage forms in the stomach from hours to days.
Delivers drugs locally in the stomach and upper small intestine, ideal for treating peptic ulcers.
Enhances patient compliance through reduced dosing frequency.

Stomach Physiology and Function

Composed of three compartments: Fundus, Body, Antrum.
Fundus and Body serve as reservoirs for ingested materials; Fundus generates positive pressure to promote content movement.
Antrum acts as a mixing site and drain pump to the duodenum.
Stomach functions include food reservoir, processor, sterilizer, and delivery port to the intestine.

Gastric Motility

Characterized by phases: Interdigestive Myoelectric Motor Complex (IMMC) occurs during fasting and varies during feeding.
Fasted State Phases include:
- Phase I: Basal state (45-60 min) with minimal contractions.
- Phase II: Preburst state (30-45 min) with increased contraction frequency and strength.
- Phase III: Burst state (5-15 min) clears out digested material, known as “Housekeeper waves.”
- Phase IV: Brief non-contraction period (about 5 min).
Fed State: Liquids empty within 30 min, solids depend on meal type, size, and density with emptying time of 2-6 hours.

Limitations of Gastro-Retentive Systems

Not suitable in the fasted state due to the risk of rapid gastric emptying.
Release rate influenced by the IMMC phase.
Single-unit dosage forms may unpredictably empty all at once.
Continuous food consumption needed to maintain gastric retention.

Factors Influencing Gastric Retention

Density: Dosage forms with density <1 g/cm³ float; high-density forms sink, affecting retention.
Size and Shape: Larger than 7 mm has better retention; irregular shapes enhance residence time.
Food Intake: Viscosity, volume, caloric value, and frequency of meals impact retention.
Demographics: Females and elderly have slower gastric emptying rates; posture has negligible effect.

Suitable Drugs for Gastro-Retentive Systems

Drugs with local activity in the stomach (e.g., Misoprostol, antacids).
Drugs with narrow absorption windows (e.g., L-DOPA, furosemide).
Instable drugs in intestinal environments (e.g., Captopril, Metronidazole).
Drugs that affect colonic microbes (e.g., Helicobacter pylori antibiotics).
Drugs with low solubility at high pH (e.g., Diazepam).

Unsuitable Drugs for Gastro-Retentive Systems

Drugs with limited acid solubility (e.g., Phenytoin).
Drugs unstable in gastric environment (e.g., Erythromycin).
Drugs meant for targeted colonic release (e.g., 5-aminosalicylic acid).

Types of Gastro-Retentive Drug Delivery Systems

Floating Systems: Low-density systems that remain buoyant in the stomach for prolonged release.
Expandable Systems: Hydrogels that swell to prevent gastric emptying yet degrade over time.
Swelling Systems: Superporous hydrogels that expand significantly in gastric fluid.
Bioadhesive Systems: Adhere to gastric walls, increasing retention time.
High Density Systems: Designed to sink and remain in the gastric cavity.

Variants of Floating Drug Delivery Systems

Effervescent Systems: Utilize gas-generating components that create buoyancy.
Non-Effervescent Systems: Expand through absorption of gastric fluid, preventing exit.
Colloidal Gel Barrier Systems: Feature rapidly swelling polymers that create a buoyant environment; examples include Madopar and Valrelease.
Alginate Beads: Floating beads that prolong gastric residence up to 5.5 hours through freeze-dried calcium alginate method.
Hollow Microspheres/Microballoons: Float in acidic media for over 12 hours utilizing a novel emulsion method.

Requirements for Superporous Hydrogels

Easily swallowable size, preferably housed in size 000 capsules.
Fast swelling capability to prevent gastric emptying.
Swollen size must be large enough to be retained in the stomach.
Strong enough to withstand gastric contractions and shear forces.

Conclusion

Gastro-retentive drug delivery systems hold promise for improving therapeutic outcomes by enhancing drug retention in the gastric region, targeting specific drugs for effective local action, and tailoring designs to optimize performance based on physiological understanding.

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Description

This quiz explores the gastro-retentive drug delivery system, focusing on its objectives, such as prolonging the residence time of oral dosage forms in the stomach. It also highlights its effectiveness in delivering drugs locally for conditions like peptic ulcers. Understanding stomach physiology and function is essential for enhancing patient compliance.