Clinical Pharmacology and prescribing drugs Flashcards
What is pharmacodynamics?
What the drug does to the body
What is pharmacokinetics?
what the body does to the drug
What is clinical pharmacology?
the study of clinical effectsof drugs on patients
What factors affect the choice of therapeutics?
Underlying disease
Drug data (efficacy, safety, licensed etc.)
Owner needs (financial, physical)
Patient factors
Practice (stock)
Compliance (training and education)
What are the different types of molecules that drugs can target?
Receptors (agonists or antagonists)
Ion channels
Structural Proteins
Enzymes
Carrier molecules
DNA
Describe the dose response curve of agonists
Response increases as dose increases up to a plateau
What is a full agonist?
A drug that reaches 100% response
What is a partial agonist?
A drug that does not elicit a full response (often used in conjunction with other drugs)
What is potency?
amount of drug required to produce 50% of its maximal effects (ED50).
What is efficacy?
the maximum therapeutic response that a drug can produce
What is drug specificity?
capacity of a drug to cause a particular action in a population - has one desired effect
What is drug selectivity?
relates to a drugs ability to target only a selective population in preference to others
What is the therapeutic index (TI) of a drug
The difference between a toxic and therapeutic doses
- High TI gives more scope to increase drug before toxic effects occur
- High TI is safer
Describe competitive antagonists
Compete with agonists for receptor binding site
Chemical structure similar to agonist
Increasing agonists overcomes antagonists
Describe non-competitive antagonists
bind to different receptor site or block ‘post’ binding chain of events
What is the effect of antagonist on a dose response curve?
shifts it the right
- agonist potency decreases
- greater conc of agonist required to reach max efficacy
What is the action of drugs on enzymes?
Bind to catalytic site
Inhibit normal reaction, thus decreased production of undesired product
What is tachyphlaxis?
loss of target sensitivity
Giving a drug continuously decreases the effect due to…
Change in receptors (become resistant to drug stimulation/conformational changes)
Loss of receptor number
Exhaustion of mediators
Increased metabolic degradation of the drug
Physiological adaptation (crosstalk between body systems, one takes over)
Drug transporters (active extrusion of the drug)
What are the different drug distribution categories?
POM-V (Veterinary Surgeon) - prescription only
POM-VPS (Vet, Pharmacist, SQP) - prescription only
NFA-VPS (Vet, Pharmacist, SQP) - non-food producing animals
AVM-GSL (General Sales List)
Schedule 6 exemption products
Describe the prescription of a POM-V drug
Can only be prescribed by a veterinary surgeon following a clinical assessment
Medicine supplied from registered premises
What does VPS stand for in drug prescriptions?
It dictates who can prescribe certain drugs
V - vets
P - pharmacist
S - SQP (suitably qualified person)
When is a medicine classed as POM-V?
required strict limitation for safe use
requires specialised knowledge to use/apply
narrow safety margin requiring above average care
government policy to demand professional control e.g., control of antibiotics
What is the difference between POM-V and POM-VPS
Does not need a clinical assessment prior to prescription
Does not need to be administered by vet, only a competent person
What must you do prior to prescribing a POM-VPS drug?
Be satisfied the person administering the drug is competent
Advise on safe administration and warnings/contraindications
What must be done before prescribing a NFA-VPS drug>
No clinical assessment required
Person administering must be competent
Advise on safe administration and warnings/contraindications
What are medicines in the small animal exemption scheme?
Medicines for use in certain pet species (aquarium fish, cage birds, ferrets, homing pigeons, rabbits, small rodents and terrarium animals)
Can only be prescribed by vets after a clinical exam
How are safety standards regulated in the SAES?
These medicines are exempt from the requirement for a marketing authorization and not required to prove safety, quality or efficacy, but must be manufactured to same standards as authorized medicines and are subject to pharmacovigilance reporting
Why may a drug be controlled?
it can be misused by humans for recreational purpose
May be a drug with a large effect
What factors must be considered in the supply process of a prescription?
Access by staff/public
Stock control and out of date medicines
Labeling
Authorisations for prescribing
Safety and contraindications
Hand over SOPs
Prescription has all necessary details on it
What are the rules regarding records of drugs?
Receipt and supply of prescription medicines
Date of supply/receipt, name, batch, quantity, address
Copies of all written prescriptions
Records of recent audit
Imported drugs maintained
MUST BE KEPT FOR 5 YEARS
