Clinical Pharmacology Flashcards
Define pharmacodynamics
What the drug does to the body => the action
- What does it target
- What is the response
Define Pharmacokinetics
What the body does to the drug => movement of the drug in the body
- Where the drug goes
- Therapeutic plasma concentrations
What is clinical pharmacology and what are the 3 aims
The study of the clinical effect of drugs on patients
Aims:
1. Right drug
2. Right dose
3. Right onset and duration of action
What is the rationale behind therapeutics
Do no harm
Selection of appropriate drugs
Name the 6 interacting considerations of therapeutics
- Disease factors - specific diagnosis
- Drug - efficacy and safety
- Owner - financial and physical ability
- Patient - temperament, underlying factors
- Practice - drug buying power
- Compliance - training and education
Name the 6 drug targets
- receptors
- ion channels
- structural proteins
- enzymes
- carrier molecules
- DNA
What is the shape of the dose-response curve of an agonist
Sigmoidal shape
What is the difference between a partial and full agonist
Full = activation is 100%
Partial = activation is <100%
Partial agonists have lower efficacy than full agonists – even with maximal occupancy of receptors.
What is the potency of a drug
The maximum therapeutic response that a drug can produce
Define efficacy of a drug
Amount of drug required to produce 50% of its maximal effects
What is the difference between ED50 and EC50
ED50 = effective dose - the dose for 50% of the population to obtain the therapeutic effect
EC50 = Effective concentration - the dose required for an individual to experience 50% of the maximal effect
Define the specificity of a drug
Capacity of a drug to cause a particular action in a population
Define the selectivity of a drug
Relates to a drugs ability to target only a selective population
Define the therapeutic index of a drug
Therapeutic index = levels between drug becoming effective and becoming toxic
Want to make it as wide as possible
How to calculate the therapeutic index
TI = Toxic dose/therapeutic dose
How do non competitive antagonists work
Bind to a different receptor site OR
Block ‘post’ binding chain of events (act further downstream of the receptor
How does a competitive antagonist affect the agonist dose response curve
Shifts the agonist dose-response curve to the right
What is mean by “competitive antagonism is surmountable”
Additional agonist added can overcome the receptor blockade
Name 3 actions a drug can have on an enzyme
Bind to the catalytic site
Inhibit normal reaction
Decreased production of the product
Define tachyphylaxis
Loss of target sensitivity
The effect of a drug can decrease when given continuously or repeatedly
Name some causes of tachyphylaxis (x4)
Change in receptors - become resistant to drug stimulation
Loss of receptor numbers
Exhaustion of mediators
Increased metabolic degradation of the dug
Give the equation for calculating concentration
Conc = Mass/volume
Define a percentage w/v solution
A 1% w/v solution is 1g (of powder) dissolved in 100 ml
Give the equation for dilution factor
DF = Conc of stock/conc of final solution
OR
C1V1 (what we want) = C2V2 (what we have)
Give the equation for drip rate
DR = Total volume/time x drop factor
Name the 2 types of allometric scaling for drugs
- surface area
- metabolic rate
Give the equation to work out metabolic rate
Minimum energy cost (kcal/day) = K x (weight in kg) x 0.75
Where K is an energy constant
When is the drug cascade used
When no authorised vet medicines are available for that species and condition
Describe the 6 steps of the prescribing cascade
- A suitable veterinary medicine authorised for the species AND indication in GB
- A suitable veterinary medicine authorised for the species AND indication in NI
- A suitable veterinary medicine authorised in GB/NI/UK (different species or conditions)
- EITHER: A Veterinary medicine authorised outside the UK OR A Human medicine authorised in UK/GB/NI
- Extemporaneous preparations (veterinary specials)
- In exceptional circumstances: Human medicines authorised outside the UK
