Lecture 22 - Oral versus parenteral management of CVD / Enzymology

Question 1

What are the advantages of parenteral drug administration?

Answer 1

• Drug not broken down in GI tract
• 100% bioavailability
• Localised effect – eg injections into joint, ocular, intradermal
• Systemic effect – IV injection drug delivered directly into circulation
• Rapid onset of effect (iv injection)
• Drug administered in unconscious patient
• Delayed onset of effect of effect/ few dosing (IM injection once a month)

Question 2

What are the disadvantages of parenteral drug administration?

Answer 2

-Use of needle (needle phobia, needlestick injury)
- Painful
- Preparation needs to meet stringent specifications (expensive)
- Limited self-administration

Question 3

What is an intravenous injection?

Answer 3

Administration into easily accessible vein

Question 4

What is the volume of an IV injection?

Answer 4

1ml

Question 5

What is the volume of IV infusion?

Answer 5

Several litres

Question 6

What is thrombophlebitis?

Answer 6

Damage to vein

Question 7

How is thrombophlebitis minimized?

Answer 7

With the use of a central line

Question 8

What causes damage to veins?

Answer 8

• Drugs with high/ low pH
• Hypertonic solutions

Question 9

How is thrombophelitis minimised?

Answer 9

With the use of a central line

Question 10

Can suspensions be administered via central line?

Answer 10

No - particles block capillaries

Question 11

What is required for central dosing?

Answer 11

Emulsion

Question 12

How are most paranteral drugs administered?

Answer 12

IV

Question 13

What is intracardiac administertration?

Answer 13

Drug administration directly into the heart

Question 14

When is intracardiac administration used?

Answer 14

Only for life threatening emergancy

Question 15

What is the injection volume for intradermal administartion?

Answer 15

0.2ml

Question 16

What is intradermal administration typically used for?

Answer 16

Vaccination

Question 17

What angle is intradermal administered at?

Answer 17

10 to 15 degreeds

Question 18

What angle is subcutaneous administered at?

Answer 18

45 degrees

Question 19

What angle is intramuscular administered at?

Answer 19

90 degrees

Question 20

What layer is intradermal administered into?

Answer 20

Dermis

Question 21

What layer is subcutaneous administered into?

Answer 21

Subcutaneous tissue

Question 22

What layer is instramuscular administered into?

Answer 22

Muscle

Question 23

What is subcutanous also known as?

Answer 23

Hypodermic

Question 24

Where are subcutanous injections administed into?

Answer 24

Subcutaneous fat

Question 25

What is the injection volume for subcutaneous administration?

Answer 25

1ml

Question 26

What are the advantages for subcutanous administration?

Answer 26

- Quite fast administration - Predictable eg insulin

Question 27

What formulation are subcutaneous injections?

Answer 27

- Aqueous solutions - Suspensions

Question 28

Where are intramuscular injections administered?

Answer 28

- Buttock - Thigh - Shoulder muscle

Question 29

What is the volume of intramuscular injections?

Answer 29

Up to 4ml

Question 30

Is intramuscular administration faster or slower than subcutaneous administration

Answer 30

Slower

Question 31

What is the injection volume of intrathecal injections?

Answer 31

Up to 10ml

Question 32

What formulation are intrathecal injections?

Answer 32

Aqueous solutions

Question 33

Where are intrathecal drugs administered?

Answer 33

Into cerebrospinal fluid

Question 34

What are the two intermost protective membranes of spinal chord?

Answer 34

- Arachnoid mater - Pia mater

Question 35

Where is the cerebrospinal fluid?

Answer 35

In the subarachnoid space between arachnoid mater and pia mater

Question 36

What are intrathecal drugs used for?

Answer 36

To introduce drugs that cannot cross the blood brain barrier eg antibiotics to treat menengitis or anticancer agents

Question 37

Where are epidural injectios administered?

Answer 37

Into epidural space eg spinal anaesthesia

Question 38

Where are intra articular injections delivered?

Answer 38

Into synovial fluid of jount cavities

Question 39

What drugs are usually given via intra-articular injections?

Answer 39

Anti-inflammatory drugs to treat arthritic conditions

Question 40

Where are opthalmic injections administered?

Answer 40

Around on into the eye

Question 41

What is the volume of ophthalmic injections?

Answer 41

1ml

Question 42

Where are intracameral injections administered?

Answer 42

Into anterior chamber of the eye - infront of lens

Question 43

What is the maximal volume of ophthlamic injections?

Answer 43

0.1ml

Question 44

What happens if ophthalmic injections exceed the maximum volume?

Answer 44

Rise in intra ocular pressure

Question 45

What are the pharmacopoeial requirements for injections?

Answer 45

- Sterility - Excipients - Containers - transparent to permit inspection of contents - Free from endotoxin and pyrogens - Free of particles - For emulsions for IV injection droplet less than 3nm to prevent oil embolism

Question 46

What can injections be?

Answer 46

- Solutions - Emulsions - Suspensions

Question 47

What injections are used for local action?

Answer 47

- Intra articular - Intra ocular

Question 48

What injections need to be absorbed for systemic effect?

Answer 48

- Intramuscular - Subcutaneous

Question 49

How long do IM and SC injections of solutions usually take to absorb?

Answer 49

Within 30 mins

Question 50

How long do IM injections of suspensions take to act?

Answer 50

1 - 7 days

Question 51

How long do IM oily injections take to act?

Answer 51

Up to 4 weeks

Question 52

How long do intra-articular injections of suspensions take to act?

Answer 52

Act over many weeks

Question 53

What are three vehicles for injections?

Answer 53

- Water for injections (highly purified water) - Solubelising agents (eg cyclodextrins) - Oils

Question 54

Give examples of oils used for injections

Answer 54

- Lecithin - Sorbitan fatty acids - Arachis oil - Sesame oil

Question 55

What is the pH of plasma?

Answer 55

7.4

Question 56

What pH can injections be?

Answer 56

Between 3 and 9

Question 57

What is used to adjust the tonicity of injections?

Answer 57

- Dextrose - Mannitol

Question 58

What is the purpose of enzymes?

Answer 58

- Powerful catalysts

Question 59

What do catalysts do?

Answer 59

Increase the rate of a reaction by up to 1 million fold but don't change the equillibrium of the reaction

Question 60

How do catalysts accelerate reactions?

Answer 60

By stabilising the transition state

Question 61

Describe the transition state?

Answer 61

- Highly unstable - Energetically unfavourable - Reaction intermediate

Question 62

How do enzymes affect the activation energy?

Answer 62

Lower the activation energy of a reaction but G stats the same

Question 63

What is the reaction surface for enzyme catalysis?

Answer 63

The active site

Question 64

What is a suitable environment for enzyme catalysis?

Answer 64

Hydrophobic

Question 65

What is the active site?

Answer 65

Small hyrdrophobic hollow or cleft on the enzyme surface

Question 66

What does the active site contain?

Answer 66

Amino acids

Question 67

What do amino acids in the active site do?

Answer 67

- Bind reactants (substrates and cofactors) - Catalyse the reaction

Question 68

What are the models of active site binding?

Answer 68

- Lock and key - Induced fit

Question 69

What is induced fit?

Answer 69

- The active site is nearly the correct shape for substrate. - Binding alters the shape of the enzyme - Strains bonds in substrate: involves intramolecular bonds between function groups in substrate and active site

Question 70

What are the strongest bonding forces?

Answer 70

Ionic

Question 71

What are the weakest bonding forces?

Answer 71

Van der waals