Administering drugs by the enteral route. Flashcards Preview

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Flashcards in Administering drugs by the enteral route. Deck (39)
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1
Q

What is enteral drug administration?

A

Route of entry is GI tract.

2
Q

Name the enteral drug administration methods.

A
Oral
Rectal 
Buccal
Sub - Lingual 
Nasogastric
Nasojejunal 
Gastrotomy
Jejunostomy
3
Q

Why is enteral drug administration used?

A

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

4
Q

What is contained within the gastro - intestinal tract?

A
Salivary glands
Pharynx 
Mouth
Oesophagus
Liver
Gallbladder
Stomach 
Pancreas 
Small Intestine
Large Intestine 
Anus
5
Q

What is the pH in saliva?

A

pH 6.7

6
Q

What are the enzymes present in saliva?

A
Amylase = Breaks down carbohydrates.
Lipase = Breaks down lipids.
7
Q

How is food broken down in the mouth?

A

Chewing causes food to be broken down in the stomach.

8
Q

What is the pH in the stomach?

A

pH 1.5 - 3.5

9
Q

What are the enzymes present in the stomach?

A

Pepsin / Chymotrypsin etc

10
Q

What happens in the stomach?

A

Food is processed into chyme via gastric and muscular contraction.

11
Q

What is chyme?

A

Pulpy acidic fluid.

12
Q

What is absorbed in the stomach?

A

Drugs like aspirin and warfarin.

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

13
Q

What are the 4 layers of the stomach?

A

Mucosa
Sub - mucosa
Muscle
Serosa

14
Q

What is the pathway of digested material from the stomach?

A

Small Intestine
Duodenum
Jejunum
Ileum

15
Q

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

A

Duodenum
Jejunum
Ileum

16
Q

What are the 2 substances released in the duodenum?

A

Pancreatic Secretions and Bile.

17
Q

What does bile excrete?

A

Excretes bilirubin and aids in fat absorption via fat absorption.

18
Q

What does pancreatic secretions contain?

A

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

19
Q

What is the function of the large bowel?

A

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

20
Q

What is first pass metabolism?

A

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

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

21
Q

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

A

First - pass metabolism

Molecules may be rendered ineffective BEFORE reaching site of action.

22
Q

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

A

Immediately excreted in bile

May be reabsorbed (enterohepatic recirculation).

23
Q

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

A

Lined with closely packed cells with tight junctions between them.

24
Q

How can molecules pass through the cell?

A

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

25
Q

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

A

Transcellular Route

Paracellular Route

26
Q

What is the transcellular route?

A

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

27
Q

What is the paracellular route?

A

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

28
Q

What is lipid solubility of a drug dependent on?

A

The extent of ionisation of the molecules.

29
Q

What is drug formulation?

A

The final stage in the production of a medicine.

Combines active molecule with other molecules.

30
Q

Why are different drug formulations necessary?

A

Maximises drug absorption.

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

31
Q

What enteral formulations are present?

A
Tablet
Capsule
Liquid (solution / suspension)
Foam
Wafer
Suppository
Granules
Lozenges
32
Q

What is a tablet?

A

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

33
Q

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

A

Oral = First pass metabolism.

Buccal / Sublingual / Rectal = No first pass metabolism.

34
Q

What drug factors must be taken into consideration?

A
Concentration
Formulation
Molecular Size
Lipid Solubility 
Acid - Base status
35
Q

What GI factors must be taken into consideration?

A
Motility 
Blood Supply
Absorption Surface 
Gastric Content
Bile
Enteric Bacteria
36
Q

What is Motility?

A

Rate of emptying gastric content.

Slow intestinal transit = MORE time to absorb.

37
Q

What is the effect of enteric bacteria?

A

May activate or inactivate the drug.

38
Q

What is the effect of gastric content?

A

Acid may denature the drug = Food may influence absorption.

Calcium and Tetracycline binding = other drugs may bind.

39
Q

What is the effect of bile?

A

Necessary for emulsification and absorption of fat soluble drugs.