Intro To Pharmacology Flashcards
What are the important sites of drug action?
Receptors
Enzymes
Ion channels
Transporters
How do agonist drugs work?
- Drug + receptor
- Activation
- Provokes cellular response
How do antagonist drugs work?
- Drug + receptor
- Binding - blocks receptor from signalling any further message onwards
- No response
What is an example of an antagonist drug?
Beta blockers - slow heart rate
What factors affect drug concentration in body?
Bioavailability - e.g. absorption form stomach
First-pass metabolism - e.g. activation or breakdown by liver enzymes
Clearance - metabolism and elimination through urine
What is bioavailability?
Proportion of parent drug that passes into systemic circulation after administration
Oral determinants are - level of absorption, loss in faeces, first-pass metabolism
How do you calculate bioavailability?
Compare:
Amount in circulation after oral dose
Amount in circulation after IV dose
What is drug half-life?
Time taken for drug concentration to fell to half its initial value
Main determinant of drug regimen
Tells how long drug is in body
E.g. alcohol half life in 1 hr
Typically 5 half life’s is considered to be when most of drug is eliminated by body
Why do adverse drug reactions occur?
- Dose related - elevated dose = greater risk of harm, pharmokinetic/pharmodynamic relationship
- time/duration of treatment
- individual susceptibility factors - age, physiological impairment, genetic susceptibility
How to minimise adverse affects/harm ?
- evidence-based choice of relevant drug for individual patient
- avoid drug if patient high risk of particular event
- adjustment of dose or duration
- careful monitoring to detect problems
What severe rare adverse reaction of biphosphonate ?
Osteonecrosis of the jaw
What is the severe rare adverse affect of metformin ?
Lactic acidosis
What is the severe rare adverse affect of carbimazole and clozapine?
Marrow suppression
What is the severe rare adverse affect of statins?
Myositis
