Oral Drug Delivery

Question 1

What are some disadvantages to oral dose forms

Answer 1

The degradation and metabolism

The onset of action

Question 2

What are the drug absorption sites for oral drug delivery?

Answer 2

Stomach
Small intestine (major)
There is very limited absorption in the esophagus and the colon

Question 3

What are some possible influencing factors of the stomach as an absorption site?

Answer 3

pH
Enzymes
Food
Liver metabolism

Question 4

What are some necessary drug properties for oral administration?

Answer 4

Reasonable absorption profiles (solubility, permeability, irritability)
Acceptable physical, chemicals and biological stability (temperatures, light, moisture, various pH values, enzymes, first pass metabolism)
Good processing characteristics (compatibility with excipients, compactability, compressibility

Question 5

What are the five major obstacles I oral drug delivery?

Answer 5

Solubility
Stability
Absorption
Metabolism
Drug targeting

Question 6

What are different ways to increase solubility?

Answer 6

Selecting different drug salt forms
Microionizing drug particles
Improving formulation disintegration and dissolution
Incorporating other additives

Question 7

What are the advantages to oral drug delivery?

Answer 7

Effectiveness
Accuracy
Convenience
Economy

Question 8

What are some ways to improve stability?

Answer 8

Coating
Additive addition
Packaging protection
Controlled release formulation

Question 9

How can absorption extent be improved

Answer 9

Selecting the appropriate active and inactive ingredients
Increasing drug disintegration and dissolution rate
Preventing drug compounds from decomposition
Administration approaches (administer with/without food and/or water)

Question 10

How can we prevent metabolism before absorption?

Answer 10

Structure modifications
Coating
Controlled release

Question 11

How can we prevent metabolism after absorption?

Answer 11

Pro drugs

Question 12

What are some special delivery systems that may help with drug targeting?

Answer 12

Micro capsules
Liposomes
Nanoparticles
But these systems are better IV

Question 13

What is sustained release?

Answer 13

Sustained release constitutes any dodge form that provides medication over an extended period of time

Question 14

What is controlled release?

Answer 14

Controlled release denotes that the system is able to provide some actual therapeutic control (I.e., controlling drug concentrations in the target site)

Question 15

What are some characteristics unique to controlled release dosage forms?

Answer 15

Enables the patient to take less amount of drug with fewer administration frequencies (minimizes adverse effects and accumulation)
Enhance therapeutic outcome by modifying drug release rate, reducing drug concentration fluctuations and improving drug bioavailability
Patient compliance
The average cost of treatment over an extended time period is reduced (sometimes)
More stringent quality control

Question 16

What should the half life of a controlled release drug be?

Answer 16

2-8 hours

Question 17

How quickly should the drug be absorbed?

Answer 17

Within 3-4 hours (faster than the rate of drug release)

Question 18

What is the optimal drug dose for controlled release formulations

Answer 18

Maximum of 0.5-1g

Question 19

The mechanisms by which drug is released from controlled release products is:

Answer 19

Diffusion
Dissolution
Combination diffusion and dissolution
Osmotic pressure

Question 20

What are the 3 systems of controlled release?

Answer 20

Reservoir system
Matrix system
Bioerodible system
Dissolution-controlled systems
Osmotic pumps

Question 21

Describe the reservoir system

Answer 21

This type of controlled release formulation is characterized by a core of drug (drug reservoir) surrounded by a polymeric membrane

Dissolution medium has to diffuse across the membrane to dissolve the drug, which will then diffuse through the membrane too deliver the drug content

Question 22

Describe matrix systems

Answer 22

Matrix systems consist of drug dispersed homogeneously throughout a polymer matrix

Question 23

Describe bioerodible systems

Answer 23

Bioerodible systems are made of drug components homogenously dispersed in chemical polymers (the polymers are water-soluble, so drug ingredients and matrix polymers dissolve and release at the same time)

Question 24

How can drug release be controlled by pure dissolution mechanism?

Answer 24

By decreasing dissolution rate of the active ingredients. This is achieved by:

• selecting appropriate salts or derivatives with lower solubility,
• coating the drug with slowly dissolving material, or,
• incorporating it into a tablet with a slowly dissolving carrier

Question 25

Describe osmotic pumps

Answer 25

Osmotic pumps rely on osmotic pressure as the driving force to control drug release form the systems.
Drug cores consist of a mixture of active ingredient and osmotic-pressure producing agents

Question 26

How are osmotic pumps manufactured?

Answer 26

The cores are coated with a semi-permeable polymer and an orifice is drilled on the surface of the coating by a laser beam
After in contact with the dissolution medium, water will penetrate into the core and dissolve the components, the osmotic pressure produced will then drive the drug out of the membrane through the small orifice