Pharmacology Flashcards
Define pharmacodynamics
What drug does to body
Action of a drug
What does it target
What is the response
Define pharmacokinetics
What body does to drug
Movement of drug within body
Where does drug go
Therapeutic plasma concentration
List considerations when selecting a drug
Correct indication with no contra-indications (safe & effective)
Efficacy
Effectiveness of drug to treat condition
Evidence-based whenever possible
Not same as potency - Strength of drug – how much is needed
Route of administration
Ease of administration
Different onset of activity
Legislation
Veterinary medicines directorate (VMD) = regulatory body for veterinary medicine
Pathophysiological status of animal
e.g. young, old, pregnant etc.
Short (acute) vs long term (chronic) therapy
Cost
Owner education
Can owner administer it properly
Farm animal
Meat/milk withdrawal
Individual/group
Describe the life of a drug
- Absorption (stomach/intestine)
- Distribution (blood)
- Acts on target
- Metabolism (liver/lungs)
- Excretion (GI tract/kidney)
Describe absorption & uptake of drugs
Influenced by:
Route of administration
IV faster than oral
Physiochemical properties of drugs
Status of GI tract
e.g. acidity of stomach, motility
Taken with food
Formulation
e.g. fast acting vs slow release
Describe distribution of drugs
Drugs transported in plasma
Most drugs temporarily bind to plasma proteins – inactive when bound
Free (unbound) drug is active & can leave blood to different body fluid compartments – can affect desired & undesired tissues
Different drugs will distribute to different extends
Describe drug elimination by metabolism
Drugs can be metabolised & thus inactivated
Not always metabolised the first time it goes through liver
Metabolised so its more water soluble
Drug metabolite then excreted by kidney
Describe drug elimination by excretion
Some drugs directly eliminated in urine by kidney
Often polar drugs
e.g. penicillin
Metabolised drugs also excreted by kidney
Renal disease can impact levels & thus efficacy of drug
What are the main targets at which drugs act
Receptors
Ion channels
Enzymes
50% of drugs
Typically enzyme inhibitors & thus decrease their activity
e.g. penicillin blocks cell wall synthesis in E. coli
Carriers
Define adverse events
Unwanted side effects
Includes drug having no effect
2 broad types
Predicted
Idiopathic (unpredicted)
If in doubt, report it
What are neurotransmitters
Chemical substances which are released at end of nerve fibre by arrival of nerve impulse
Diffuse across synapses & effect transfer of impulse from one nerve fibre to another
e.g. acetylcholine, dopamine, serotonin, GABA, glutamate, noradrenaline, histamine
Give examples of drugs that influence cholinergic transmission by acting on postsynaptic ACh receptors as agonists or antagonists
Muscarinic agonists
Pilocarpine – dry eye
Muscarinic antagonists
Atropine – speeds up heart
Scopolamine – abdominal pain
Nicotrinic agonists
Suxamethonium
Nicotinic antagonists
Α bungarotoxin
Give examples of drugs that influence cholinergic transmission by affecting release or destruction of ACh
Drugs affecting ACh release
B- & Y- bungarotoxin
Botulinum toxin
Drugs that inhibit ACh
Carbamate insecticides, organophosphates
Give examples of drugs that influence adrenergic transmission by acting on postsynaptic adrenoreceptors
Agonists
A1: adrenaline for cardiac arrest
A2: medetomidine for sedation
B1: dobutamine to increase BP
B2: salbutamol for asthma
Antagonists
A2: atipamezole for reversal of sedation
B: propanolol
