Pharmacology Flashcards
1
Q
What is pharmacology
A
Study of drug action on the body
2
Q
What is pharmacokinetics
A
The study of what the body does to a drug
3
Q
What is pharmacodynamics
A
Physiological effects of a drug on the body
4
Q
What does ADME mean in pharmacokinetics
A
Absorption
Distribution
Metabolism
Excretion
5
Q
If a drug is given orally, where does it go
A
GI tract
6
Q
What happens when a drug is absorbed by the GI tract
A
Goes to the liver where some drugs are broken down
7
Q
How can elimination happen
A
Broken down by liver
Excreted by kidneys
Excreted via lungs
8
Q
Where does pharmacological action happen
A
Circulation tissue space
9
Q
What is absorption
A
Rate and extent at which a drug leaves its site of administration and enters the circulatory system
10
Q
What can impede the efficacy of a drug
A
Route of administration e.g. orally or rectally
11
Q
What can enhance or impair the rate of absorption
A
Presence of food
12
Q
What happens when the GI tract is compromised
A
A parenteral route must be considered
13
Q
Why does location of drug administration need to be considered
A
Tissue perfusion will also impact on absorption
14
Q
What is first pass effect
A
When a drug has been absorbed into circulation it is transported to the liver via hepatic portal system where it is metabolised
15
Q
Why do we have to reduce the amount of active drug being distributed within the body
A
Because some drugs undergo extensive hepatic metabolism
16
Q
What is produced by first pass effect
A
Drug and metabolites
17
Q
How can first pass effect be avoided
A
Using parenteral route which bypasses this process and provides body with a more accurate dosage
18
Q
Once a drug has been metabolised by the liver, where does it go
A
Enters the systemic circulation and travels in the plasma to its site of action
19
Q
What happens once a drug has reached the desired site of action
A
It leave the plasma and enters interstitial fluid then the cells and combines cellular receptors to create an action
20
Q
What affects drug distribution
A
Drug formulation
Blood flow to that area
Binding/unbinding of the drug to plasma proteins
Presence of anatomic barriers
21
Q
What are fat loving drugs
A
Lipophilic
22
Q
What are water loving drugs
A
Hydrophilic
23
Q
Which route of administration is best for hydrophilic drugs
A
IV, IM as they enter the extra cellular fluid
24
Q
Which route of administration is best for lipophilic drugs
A
Orally or SC as needs rap diffuse through a cell membrane
25
When are drugs most rapidly distributed. Give examples
When entering well perfused tootsies e.g. active skeletal muscle, liver, kidney, brain
26
Which tissues are poorly perfused
Inactive skeletal muscle and adipose fats
27
What remains in the circulation as a reservoir for circulating drugs
Plasma proteins
28
What happens when a drug binds with a plasma protein (albumin)
Termed inactive and unable to migrate into the tissues to exert its effect
29
What happens to drugs that do not bind to plasma proteins
Able to migrate into tissues and exert effect
30
What happens to the amount of unbound and bound drug after plasma protein binding
Drug within circulation will remain the same
31
What happens to bound molecules when unbound drug molecules move into tissues during plasma protein binding
Bound molecules are released to maintain the balance
32
Why is protein binding significant
Because plasma protein levels are reduced due to disease as the standard dose could cause toxic concentrations
33
Which organs can cause toxic concentrations of drugs
Liver, GI, kidney
34
Why are anatomical barriers important
In the capillaries of the CNS as endothelial cells in the brain are closely packed together preventing some drugs from entering
35
What type of drugs can cross the blood:brain barrier
Lipophilic
36
What happens to drugs before they can be excreted
Biotransformation / drug metabolism
37
Where does bio transformation happen
Generally in liver (lungs and kidneys)
38
What happens when drugs are metabolised
Enzymes modify the molecules of the drug to enable elimination
39
What does enzyme action do during metabolism
Provokes chemical reactions that cause drug to become hydrophilic enabling drug to be eliminated by kidneys
40
Factors affecting drug metabolism
Species, age, nutritional status, health status
41
Where does excretion take place
Liver, lungs, skin, glands e.g. mammary, sweat and salivary
42
Why does excretion route need to be taken into consideration
Could compromise effectiveness of excretion when specific organ is diseased
43
Why is pharmacokinetics important
Formulates suitable drug dose and dosing regime to facilitate therapeutic effect
44
Pharmacokinetic parameters:
Bioavailability
Volume of distribution
Clearance and half life
45
What is bioavailability
The quantity of the administered drug reaching systemic circulation
46
When is bioavailability reduced greatly from 100% IV
When given orally
47
What is volume of distribution
Measurement relating to the amount of drug absorbed within the plasma, body tissues and cells
48
What properties of a drug affect a drugs ability to distribute
Interaction with plasma proteins, drug for me.g, hydrophilic or lipophilic
49
What is clearance
Volume of blood cleared of a drug from eliminating organ e.g. liver, kidneys
50
What is important when devising a drug regime for a patient regarding clearance
To enable suitable serum drug concentrations. Must be equal to the rate of drug administration
51
What is half life
Time it takes for drug to be reduced by 50% at current concentration level
52
What can greatly affect the plasma concentration of a drug
Efficacy of kidneys and liver as half life will take longer to decrease
53
Why is pharmacodynamics important
Ensured indication for using specific drug has been discussed and any contraindications have been evaluated
54
What to cellular receptors normally interact with regarding drug-receptor interaction
Endogenous Ligands
55
What are endogenous ligands
Natural substances e.g hormones and neurotransmitters
56
How does a drug exert its effect
By binding to a protein receptor found in the cell membrane, cytoplasm or nucleus
57
What is affinity
Ability of a drug to bind to receptor
58
What is efficacy
Ability of a drug to produce the desired effect
59
What is an agonist
Drug that has good affinity and efficacy
60
What is an antagonist
Drug that has poor affinity and efficacy
61
What is the therapeutic effect
Effect of a drug within an Animals body to control a specific disease or manage physiological function. The narrow dosage parameter a drug has to remain in, to enable therapeutic effect to be efficient
62
What happens when therapeutic range is too high
May produce toxic effect. MSC: maximum safe concentration or MTC: minimum toxic concentration
63
What happens when the therapeutic range is too low
Prevents the desired effect and termed minimum effective concentration (MEC)
64
How long does a prescription last for
6 months for normals drugs. Can be on repeat
| 28 days for controlled drug. Cannot be on repeat
65
Requirements for POM-V
Once prescribed by VS who is confident the person using it is competent to do so.
Drug will have safety issues or concerns, deemed that specialist knowledge is required, drug has narrow safety margins and is government policy
66
Requirements for POM-VPS
Registered qualified person e.g. vs, pharmacist or SQP. Prior clinical assessment is not prerequisite
67
Requirements for POM-V (CD)
Dispensed once prescribed by VS
Drug access must be by person deemed confident by vs to handle
VS will have key
68
Pros for oral administration of medication for owners
Easy for most owners
69
Cons for oral administration of medication
Slow compared to parenteral
Not suitable for unconscious/vomiting patient
Food can impact on administration
Can cause irritation (V/D)
Gastric acid can denature drugs
Liver enzymes may break down drugs before it reaches systemic circulation
70
Pros of parenteral administration of medication
Directly into systemic circulation therefore 100% bioavailability
Drug action achieved quickly
Drugs can irritate skin
71
Cons of parenteral administration of medication
```
Requires asepsis
Must be solution
Must be given slowly
Irritant drugs can cause severe tissue damage
Catheter care
```
72
Pros of IM administration of medication
Can be suspended drug
| Absorbed quicker than SC
73
Cons of IM medication administration
small volumes at a time
2ml in cats
5ml in Dogs
74
Pros of SC administration of medication
Can be large amounts of fluid
| Generally pain free
75
Cons of SC medication administration
Multiple sites should be used for high volumes of fluid to avoid discomfort
Possible damage to small blood vessels
Local reaction to drug can occur
76
Where do you admin IM injections and how long does it take
Quadriceps of hindlimb takes 20-30 minutes
77
How long does SC injection take to work
30-45 minutes
78
What is intaosseous
Injection into bone marrow in medulla of long bone; when IV is compromised e.g. birds
79
What is epidural
Aseptic technique of injecting into vertebral canal outside the duramater
80
What is intrarthecal
Aseptic technique of injection into subarachnoid space containing cerebrospinal fluid; contrast media for myelography
81
Subconjunctiva
Into conjunctival membrane of eye
82
Legal requirements to f dispensing label for medication
- Name and address of animal and owner
- Name and address of approved premises supplying the medication
- Date of supply
- The words ‘keep out of reach of children’
- The words ‘for animal treatment only’
83
Discuss the cascade system
1. Veterinary medicinal produce authorised in the UK for another condition in the same species or another species with the same condition
2. Medicinal product authorised in uk for human use or veterinary product authorised in eu member state for use in animal species
3. Veterinary product made by vs, pharmacologist or person holding manufacturers authorisation as prescribed by vs
84
Key information given to clients when dispensing medication
- Technique demonstration e.g. using pill guns, filling syringes and tube feeding.
- Specific requirements for drug e.g. before food
- Potential side effects/contraindications and client told to phone if this happens
- Told when to stop medication and told to return an medication if necessary
- Person dispensing should be confident client is happy doing what is expected
85
Requisition requirements for schedule 2 drugs
Made in writing to supplier, signed by vs
86
Storage requirements for schedule 2 drugs
Locked cabinet secured to wall or floor
Destruction must take place in front of authorised person
Invoices kept for 2 years
87
Dispensing requirements for schedule 2 drugs
Drug register kept with all purchases and each supply within 24 hours
88
Requisition requirements for schedule 3 drugs
Made in writing to supplier, signed by vs (same as schedule 2)
89
Schedule 2 drugs
Morphine
Pethidine
Fentanyl
Ketamine
90
Storage requirements for schedule 3 drugs
Locked cabinet
| Invoices kept for 2 years (same as schedule 2)
91
Dispensing requirements for schedule 3 drugs
No register
92
Examples of schedule 3 drugs
Pentobarbital
Phenobarbital
Buprenorphine
Tamazepam
93
Requisition requirements for schedule 4 drugs
Prescription bed by MRCVS
94
Storage requirements for schedule 4 drugs
None
95
Dispensing requirements for schedule 4 drugs
Prescribed by MRCVS but should be checked. Can be dispensed by SQP/vet/nurse as long as checked
96
Examples of schedule 4 drugs
Benzodiazepines
| Anabolic steroid
97
Examples of schedule 5 drugs
Coedine
| Morphine (in less than specified amounts)
98
What does p.o or per os mean
By mouth
99
What does a.c mean
Before food
100
What does p.c mean
After food
101
What does q. Mean
Every
102
What does p.r.n mean
As necessary
103
What does a.s mean
Sufficient quantity
