Pharmacology 1 Flashcards
pharmacodynamics
what the drug does to the body
pharmacokinetics
what the body does to the drug
how do drugs work i.e. what do they act on
via acting on enzymes or receptors (agonists/antagonists)
Pharmacodynamic interactions
Occur when 2 drugs work via different pathways to effect the same outcome
e.g. diuretics and ACE inhibitors
why is using furosemide and ramipril together bad in heart failure?
Both lower blood pressure to the point of collapse
ADME
Absorption
Distribution
Metabolism
Elimination
First pass metabolism
When absorbed orally, drugs goes through splanchnic circulation into liver and metabolised before bloodstream.
Distribution relies on what characteristics
Lipophilic (whole body distribution), hydrophilic (stay in plasma)
Normal metabolism process in liver
- Lipophilic drug
- Phase I - oxi, red, hydrolysis
- Phase II - conjugation with glucuronide / sulphate
- Hydrophilic
Drugs with narrow therapeutic window in P450 system
Warfarin Theophylline Carbamazepine Phenytoin The OCP
Drugs which reduce efficacy of drug (by inducing P450 system)
Carbamazepine Phenytoin Rifampicin (for TB treatment, prophylaxis for meningitis - stains everything orange) Chronic alcohol intake Barbecued meat St John's Wort
Drugs which result in drug toxicity (inhibit P450)
Erythromycin Ciprofloxacin Miconazole Sodium valproate Grapefruit juice Cranberry juice
Phenytoin what happens if too high or too low
Low –> patient has fit
High –> patient becomes ataxic
What is involved in elimination
Lipophilic drug into a hydrophilic drug which goes to kidneys or gall bladder
What happens to hydrophilic drugs in terms of elimination
(e.g. digoxin) are excreted unchanged
