Dissolution Flashcards
Def of dissolution:
process where solid phase goes into solution phase
Drug delivery system is based on…
diffusion and dissolution
Most capsules and tablets are ____ and ____ order
zero and first
Zero order is achieved via…
non-disintegrating dosage form
Examples of zero order delivery systems:
- topical/transdermal
- implantable
- oral controlled release
Dissolution is also known as…
drug release
- rate limiting step
Which kind of particles dissolve the fastest?
fine particles
The ____ a dissolution rate, the better
higher
Where do the majority of drugs get absorbed?
duodenum of small intestine b/c of SA
What are the sink conditions for the dissolution rate equation?
[solute] in bulk solution is < 20% of the solubility of solid
Factors that affect the dissolution rate:
- size and viscosity
- solubility of solid
- diffusion thickness
- particle size
Increase in viscosity leads to…
decrease in diffusion coefficient and diffusion rate
Increase in solubility of solid leads to…
increase in diffusion rate
- same with increase use of salt form
What happens to the rate if a drug is diluted?
decrease in rate
A decrease in particle size leads to…
increase in SA and dissolution rate
What is the name of the dissolution rate equation?
Noyes and Whitney equation
Hixon-Crowell is used for…
drugs with uniform particles
What are some commonly used dissolution media?
- water
- 0.1 N Hcl
- buffer solution
- H2O or buffers with surfactants
- biorelevant media (simulated gastric or intestinal fluid)
What are two common dissolution media for simulating the stomach?
- 0.1 N HCl
- simulated gastric fluid (better)
What is a common buffer solution and why?
pH 6.8 b/c it’s the same pH as the duodenum
What is in simulated intestinal fluid?
pH 6.8 and intestinal enzymes
What dissolution media should you use to test drugs that might be affected by enzymes?
simulated intestinal fluid
Biopharmaceutical Classification System (BCS):
- helps predict intestine drug absorption
- based on dissolution and diffusion
- 4 classes
What is Class 1 of BCS?
high solubility and high permeability
