Pharmacology Basics Flashcards
What is Pharmacodynamics?
What the drug does to the body
What is Pharmacokinetics?
What the body does to the drug
What are Pharmacodynamic interactions?
Two drugs working via different pathways to effect the same outcome
e.g.Digoxin and Beta blockers
What does the acronym ADME stand for in Pharmacokinetics?
Absorption
Distribution
Metabolism
Eimination
What are the the possible routes of absorption of a drug?
Oral Intravenous Intramuscular Subcutaneous Sublingual /buccal Topical Rectal Intra-articular / intra-ocular
What is the difference in bodily distribution between lipophilic and hydrophilic drugs?
lipophilic drugs are distributed around the whole body
hydrophilic drugs stay in the plasma
What are the phases of metabolism of a lipophilic drug in the liver?
Phase 1: Modification
Oxidation/Reduction/Hydrolysis
Phase 2: Conjugation
with glutathione, glucuronic acid, sulphate
= Hydrophilic drug
What are the 5 important drugs to remember are metabolised by the P450 system?
Warfarin
The Oral Contraceptive Pill (OCP)
Theophylline
Carbamazepine
Phenytoin
What effect do inducers of the P450 system have?
Reduce efficacy of the drug
Name 6 Inducers of the P450 system
Carbamazepine Phenytoin Rifampicin Chronic alcohol intake Barbecued meat St. John's Wort
What effect do inhibitors of the P450 system have?
Can result in drug toxicity
Name 6 Inhibitors of the P450 system
Erythromycin Ciprofloxacin Miconazole Sodium Valproate Grapefruit juice Cranberry juice
What is a pharmacokinetic drug interaction?
When one drug affects the Absorption, Distribution, Metabolism or Elimination of another
What are the two routes of elimination for a hydrophilic drug?
Through the Kidneys in urine
Through the Gallbladder in bile
What happens during Phase 1 of lipophilic drug metabolism in the liver?
Modification
Oxidation/Reduction/Hydrolysis
What happens during Phase 2 of lipophilic drug metabolism in the liver?
Conjugation
with glutathione, glucuronic acid or sulphate
Define drug half-life
the time taken for the plasma concentration of a drug to decrease to 50% of the original value
When is drug monitoring appropriate?
Where the drug has a narrow therapeutic index
Where symptoms may be due to side-effects of the drug
Where you cannot predict how much drug the patient requires
Where there is concern that a patient may not be taking a drug
Name 6 commonly monitored drugs
Warfarin Caramazepine Phenytoin Theophylline Digoxin Lithium
What is a prescribing cascade?
Occurs when a medication is given to counteract the side-effects of another medication
What does the acronym ABCDE of Adverse Drug Reactions stand for?
A - predictable B - bizarre C - chronic D - delayed E - end of treatment effects
What are predictable adverse drug reactions?
Expected from the way that drug works, but may be exaggerated
e.g.. Hyponatraemia due to a diuretic
What are bizarre adverse drug reactions?
Cannot be predicted from the action of the drug
Uncommon but may be fatal
e.g.. Anaphylactoid reactions such as to penicillin
What are chronic adverse drug reactions?
Side effects that only occur after prolonged treatment
e.g. Cushing’s syndrome due to steroids
Gum hypertrophy due to phenytoin
Dystonias due to L Dopa medications
