Physical Pharmacy Lecture 9

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Questions and Answers

What is the primary driving force for the rate of dissolution?

Concentration gradient (correct)

Thickness of the diffusion layer

Surface area of the drug particles

Polymorphism

What is the purpose of sink conditions in dissolution testing?

To enhance the polymorphism of the drug

To increase the surface area of the drug particles

To decrease the thickness of the diffusion layer

To ensure that the dissolution medium is not saturated with the drug (correct)

How can the concentration gradient be increased?

By decreasing the surface area of the drug particles

By decreasing the concentration of the drug in the dissolution medium (correct)

By decrasing the thickness of the diffusion layer

By increasing the polymorphism of the drug

What is the effect of agitation on the thickness of the diffusion layer?

It decreases the thickness of the diffusion layer Signup and view all the answers

What is the relationship between the concentration gradient and the rate of dissolution?

As the concentration gradient increases, the rate of dissolution increases Signup and view all the answers

What is the effect of polymorphism on the dissolution of a drug?

It is not a factor in the dissolution of a drug Signup and view all the answers

What is the purpose of using a large volume of dissolution medium?

To ensure that the dissolution medium is not saturated with the drug Signup and view all the answers

What is the term for the finished dosage form that contains a drug substance, mostly associated with other inactive ingredients?

Drug product Signup and view all the answers

What is the process by which the drug leaves a drug product?

Drug release Signup and view all the answers

What is the process by which drug molecules are liberated from a solid phase and enter into a solution phase?

Dissolution Signup and view all the answers

What is the main purpose of dissolution testing?

To measure the rate of drug release from a dosage form Signup and view all the answers

What is the term for the assessment of the rate by which the drug molecules are dissolved and released from the dosage form?

In vitro drug release testing Signup and view all the answers

What is the characteristic of dissolution?

It is a time-dependent process Signup and view all the answers

Why is dissolution testing important for dosage forms that have the drug present in the solid state?

To ensure the drug product meets quality standards Signup and view all the answers

What is the relationship between dissolution and absorption of a drug?

Dissolution occurs before absorption Signup and view all the answers

What is the primary objective of performance testing in pharmaceutical dosage forms?

To quantify the amount of drug released under specific conditions Signup and view all the answers

What is the typical speed of the Rotating Basket dissolution apparatus?

50 rpm Signup and view all the answers

What is the primary purpose of selecting discriminatory dissolution conditions?

To reflect a change in drug release profile related to a change in the drug product Signup and view all the answers

Which of the following dissolution apparatus is recommended for orally disintegrating tablets?

USP Apparatus 2 Signup and view all the answers

What type of dissolution medium is used in in vitro - in vivo correlation studies?

Biorelevant medium Signup and view all the answers

What is the name of the dissolution apparatus used for testing chewing gum?

Chewing gum apparatus Signup and view all the answers

What is the purpose of selecting a specific dissolution medium?

To create sink conditions Signup and view all the answers

What characteristic of biorelevant media makes them more accurate than other dissolution media?

They contain components that replicate conditions found in the GIT Signup and view all the answers

What is the primary difference between immediate-release and extended-release tablets?

The rate of drug release Signup and view all the answers

Which of the following dosage forms is typically tested using the Franz-cell apparatus?

Semisolid topical dosage forms Signup and view all the answers

Why are dissolution conditions not chosen to mimic in vivo conditions?

Because they are generally selected to simulate in vivo conditions and not mimic them Signup and view all the answers

What is the primary factor in selecting a dissolution apparatus for a particular dosage form?

The type of dosage form being tested Signup and view all the answers

What is the purpose of dissolution testing?

To evaluate the drug's release profile Signup and view all the answers

What is the purpose of quantifying the amount of drug released during performance testing?

To assess the quality of the dosage form Signup and view all the answers

What is the pH of simulated gastric fluid?

1.2 Signup and view all the answers

What is the purpose of biorelevant media in drug dissolution?

To simulate the conditions in the body Signup and view all the answers

What is the temperature maintained at in the dissolution apparatus?

37 °C Signup and view all the answers

What is the function of Noyes Whitney in drug dissolution?

To study the dissolution rate of drugs Signup and view all the answers

What is the composition of simulated intestinal fluid?

pH 6.8, KH2PO4 (68.05g), NaOH (8.96g), and deionized water Signup and view all the answers

What is the purpose of Fick's Law in drug dissolution?

To study the diffusion of drugs Signup and view all the answers

Study Notes

Definitions and Importance

A drug product is a finished dosage form that contains a drug substance mostly associated with other inactive ingredients.
Drug release is the process by which the drug leaves a drug product.
Dissolution is the process by which drug molecules are liberated from a solid phase and enter a solution phase.

Dissolution vs. Solubility

Dissolution testing, also known as in-vitro drug release testing, measures the release of the active pharmaceutical ingredient (API) from the drug product matrix in a controlled laboratory environment.
Dissolution is a time-dependent (or kinetic) process that involves mass transfer (like diffusion).

Factors Affecting Dissolution

Concentration gradient: An increase in concentration gradient increases the rate of dissolution, and can be increased by decreasing the thickness of the diffusion layer or using large volumes of dissolution medium.
Thickness of the diffusion layer (h): Decreased agitation increases the thickness of the diffusion layer, which decreases the rate of dissolution.
Surface area of drug particles (S): Increased surface area of drug particles increases the rate of dissolution.

Methodology

Performance testing involves subjecting the dosage form to a set of conditions that will induce drug release from the dosage form and quantifying the amount of drug released under those conditions.
Conditions include the selection of dissolution apparatus (type and speed) and dissolution medium (sink conditions and temperature).

Official Dissolution Apparatus

Apparatus I: Rotating Basket (50 rpm)
Apparatus II: Paddle
Apparatus III: Reciprocating cylinder (“Bio-Dis")
Apparatus IV: Flow-through cell
Apparatus V: Paddle over disk
Apparatus VI: Rotating Cylinder
Apparatus VII: Reciprocating Holder
European Pharmacopeia: Chewing gum apparatus

Choice of Apparatus

Dosage Forms:
- Oral suspensions: USP Apparatus 2
- Orally disintegrating tablets: USP Apparatus 2
- Chewable tablets: USP Apparatus 2 or 3
- Transdermal patches: USP Apparatus 5
- Semisolid topical dosage forms: Franz-cell, enhancer cell

Special Considerations

Dissolution conditions should be discriminatory, capable of reflecting a change in drug release profile related to a change in the drug product.
Dissolution conditions are generally selected to simulate in-vivo conditions, not mimic them.
Biorelevant media simulate gut fluids accurately, containing components that replicate conditions found in the GIT.

Biorelevant Medium

Biorelevant media contain components like bile salts, phospholipids, and salts that simulate gut fluids accurately.

Noyes-Whitney Equation

The Noyes-Whitney equation describes the dissolution rate of a drug molecule.

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Description

This quiz covers the concepts of dissolution, Noyes-Whitney equation, and factors affecting dissolution in physical pharmacy, taught by Professor Ragwa Farid.