Administering drugs by the enteral route.

Question 1

What is enteral drug administration?

Answer 1

Route of entry is GI tract.

Question 2

Name the enteral drug administration methods.

Answer 2

Oral
Rectal 
Buccal
Sub - Lingual 
Nasogastric
Nasojejunal 
Gastrotomy
Jejunostomy

Question 3

Why is enteral drug administration used?

Answer 3

Emphasis of local effects.
Direct delivery to target sites.
It is also cheaper and. easier to administer.

Question 4

What is contained within the gastro - intestinal tract?

Answer 4

Salivary glands
Pharynx 
Mouth
Oesophagus
Liver
Gallbladder
Stomach 
Pancreas 
Small Intestine
Large Intestine 
Anus

Question 5

What is the pH in saliva?

Answer 5

pH 6.7

Question 6

What are the enzymes present in saliva?

Answer 6

Amylase = Breaks down carbohydrates.
Lipase = Breaks down lipids.

Question 7

How is food broken down in the mouth?

Answer 7

Chewing causes food to be broken down in the stomach.

Question 8

What is the pH in the stomach?

Answer 8

pH 1.5 - 3.5

Question 9

What are the enzymes present in the stomach?

Answer 9

Pepsin / Chymotrypsin etc

Question 10

What happens in the stomach?

Answer 10

Food is processed into chyme via gastric and muscular contraction.

Question 11

What is chyme?

Answer 11

Pulpy acidic fluid.

Question 12

What is absorbed in the stomach?

Answer 12

Drugs like aspirin and warfarin.

However, in the stomach, there is minimal absorption of nutrients and drugs.

Question 13

What are the 4 layers of the stomach?

Answer 13

Mucosa
Sub - mucosa
Muscle
Serosa

Question 14

What is the pathway of digested material from the stomach?

Answer 14

Small Intestine
Duodenum
Jejunum
Ileum

Question 15

What parts of the GI tract count as the small bowel?

Answer 15

Duodenum
Jejunum
Ileum

Question 16

What are the 2 substances released in the duodenum?

Answer 16

Pancreatic Secretions and Bile.

Question 17

What does bile excrete?

Answer 17

Excretes bilirubin and aids in fat absorption via fat absorption.

Question 18

What does pancreatic secretions contain?

Answer 18

Proteases (protein digestion) / Lipases (fat digestion) / Water secretions/

Question 19

What is the function of the large bowel?

Answer 19

Extracts water and minimal nutrients alongside elimination of remnants via faeces.

Question 20

What is first pass metabolism?

Answer 20

Key concept used in usage of drugs / humans / animals.

Drug is absorbed into the bloodstream of GI tract and enters the liver.

Question 21

What is the significance of portal circulation for drugs with hepatic metabolism?

Answer 21

First - pass metabolism

Molecules may be rendered ineffective BEFORE reaching site of action.

Question 22

What is the significance of portal circulation for drugs with hepatic elimination?

Answer 22

Immediately excreted in bile

May be reabsorbed (enterohepatic recirculation).

Question 23

What is the mucosa layer of the GI tract lined with?

Answer 23

Lined with closely packed cells with tight junctions between them.

Question 24

How can molecules pass through the cell?

Answer 24

Diffusion through lipid membrane / aqueous channels.
Membrane Transporter.
Paracellular diffusion can occur too.

Question 25

What are the two routes in the epithelium of GI tract?

Answer 25

Transcellular Route | Paracellular Route

Question 26

What is the transcellular route?

Answer 26

Where the substances travel THROUGH the cell, passing through both the apical membrane and basolateral membrane.

Question 27

What is the paracellular route?

Answer 27

The transfer of substances across an epithelium by passing through the intercellular space BETWEEN the cells.

Question 28

What is lipid solubility of a drug dependent on?

Answer 28

The extent of ionisation of the molecules.

Question 29

What is drug formulation?

Answer 29

The final stage in the production of a medicine. | Combines active molecule with other molecules.

Question 30

Why are different drug formulations necessary?

Answer 30

Maximises drug absorption. | Provides a drug delivery system by which drug delivery is optimised and provides sufficient dissolution.

Question 31

What enteral formulations are present?

Answer 31

``` Tablet Capsule Liquid (solution / suspension) Foam Wafer Suppository Granules Lozenges ```

Question 32

What is a tablet?

Answer 32

Compressed materials made of the drug / lubricants and other fillers which improve disintegration.

Question 33

What metabolism pathways does oral / buccal / sublingual / rectal take?

Answer 33

Oral = First pass metabolism. | Buccal / Sublingual / Rectal = No first pass metabolism.

Question 34

What drug factors must be taken into consideration?

Answer 34

``` Concentration Formulation Molecular Size Lipid Solubility Acid - Base status ```

Question 35

What GI factors must be taken into consideration?

Answer 35

``` Motility Blood Supply Absorption Surface Gastric Content Bile Enteric Bacteria ```

Question 36

What is Motility?

Answer 36

Rate of emptying gastric content. | Slow intestinal transit = MORE time to absorb.

Question 37

What is the effect of enteric bacteria?

Answer 37

May activate or inactivate the drug.

Question 38

What is the effect of gastric content?

Answer 38

Acid may denature the drug = Food may influence absorption. | Calcium and Tetracycline binding = other drugs may bind.

Question 39

What is the effect of bile?

Answer 39

Necessary for emulsification and absorption of fat soluble drugs.