Drug Formulation and Absorption

Question 1

What does formulation mean?

Answer 1

Process by which different chemical substances (including the active drug) are combined together in order to produce a final medicinal product.

Question 2

What does active ingredient mean?

Answer 2

Any component of the drug product intended to furnish pharmacological activity.

Question 3

What does drug product mean?

Answer 3

A finished dosage form. (IE: Tablet)

Question 4

In terms of drug movement, what are the two main routes?

Answer 4

Transcellular Route = Movement THROUGH cells and thus, directly passes through the lipid structures of the intracellular region.
Paracellular Route = Movement BETWEEN cells and is linked to small molecules.

Question 5

Which two processes are essential for drug absorption via the transcellular route?

Answer 5

Passive Diffusion and Active Transport.

Question 6

What is the transmembrane layer?

Answer 6

Cell Wall which consists of a phospholipid bilayer.

Question 7

How can drugs move through the transmembrane layer?

Answer 7

Active Transport
Facilitated Transport
Pinocytosis
Passive Diffusion

Question 8

What is the structure of a phospholipid bilayer?

Answer 8

Hydrophilic heads of the phospholipids are on the outside and the hydrophobic tails are on the inside of the phospholipid bilayer.

Question 9

Explain the process of active transport.

Answer 9

Molecules travel against the concentration gradient and therefore, requires ATP in order to transport drugs into / out of drugs.

Question 10

Explain the process of facilitated transport.

Answer 10

Molecules are transported via a carrier in the cell wall.
Therefore, ATP is NOT required for this process.
Moves down the concentration gradient.

Question 11

Explain the process of pinocytosis.

Answer 11

Requires part of the cell membrane FORMING around the molecules.
MOVES INTO CELL.
Pinocytosis transports LARGE molecules.

Question 12

Explain the process of passive diffusion.

Answer 12

Uncharged molecules passing through the cell membrane and move down the concentration gradient.
SMALL MOLECULES DIFFUSE QUICKER THAN LARGE MOLECULES.

Question 13

What are the physio - chemical properties of a drug - ionization?

Answer 13

Weak Acid = Proton - Donators

Weak Base = Proton - Acceptors

Question 14

What is an example equation of a weak base?

Answer 14

Proton acceptor + proton = proton donator.

Question 15

What is an example equation of a weak acid?

Answer 15

Proton donator = proton acceptor + proton.

Question 16

What are some examples of pKa?

Answer 16

Aspirin = pKa 3.5
Highly ionized in the plasma BUT unionized in the stomach.
Diazepam = pKa 3.5
Absorbed from the small bowel where it is unionised.
Suxemethonium = Highly ionised and not absorbed from the GI tract.

Question 17

Where is most of aspirin absorbed?

Answer 17

From the small intestine because there is a LARGE SA and thus quicker rate of absorption.

Question 18

What is an excipient?

Answer 18

Everything else in the drug which is NOT the active molecule.
Influences the pharmacokinetics and can make the product more appealing.

Question 19

Name some excipients.

Answer 19

Anti - adherents
Binders 
Coatings
Colouring / Flavouring / Sweetners
Disintegrants
Emulgents
Preservatives / Buffers / Antioxidants

Question 20

Explain the process of tablet absorption. (IE: Aspirin)

Answer 20

Stomach = Tablets are broken up here and thus, active molecule is released for absorption. Some absorption occurs here as the molecule is UNIONIZED.
Enters the small intestine and from there is passed via the hepatic portal vein to the liver.
Liver = First pass metabolism occurs and finally, enters the systemic circulation for entire body spread.

Question 21

What are two examples of drug formulation which can affect absorption?

Answer 21

Modified Release = Delivers drug over continuous period of time.
Enteric Coating = Coating which prevents dissolution or disintegration in the stomach.

Question 22

Name four ‘other’ delivery systems of drugs.

Answer 22

Buccal Wafers
Solid Gels
Patches
Ointments