Drug Interactions Flashcards
Three problems the pharmacy industry is facing
- Aging population
- Polypharmacy
- Lifestyle (e.g. usage over the counter drugs has increased)
What are the five risk factors faced by patients today
- Polypharmacy
- Old Age
- Genetics
- Hepatic Disease
- Renal Disease
What are three issues to consider with drugs
- A narrow therapeutic drug
- Steep dose
- Saturable metabolism
What five characteristics do we look for when considering the way a drug is absorbed
- Motility
- Acidity
- Solubility
- Complex formation
- Direct action on enterocytes
What main characteristic do we look for when considering how a drug is distributed
Protein binding
Three mechanisms of drug metabolism
- Action of CYP450
- Inhibition
- Induction
Name two types of CYP450 enzymes
CYP1A2
CYP3A4
Three most important classes of CYP
1,2,3
Consequence of drug A blocking metabolism of drug B (inhibition drugs)
More drug B stays in the plasma (increased effects)
Effect of induction drugs
Drug C induces CYP450 isoenzyme, leading to increased metabolism of drug D -> decreased therapeutic effects
What CYP is effected by grapefruit juice
CYP3A4
How does grapefruit juice affect CYP3A4
Increases bioavailability
What drug has major interaction with Antiarrythmic agents
Amiodarone
What drug has major interactions with antihistamines
Diphenhydramine
Terfenadine
Minor interactions of drugs with Ca Channel antagonists
Nimodipine
Nicardipine
Felopdipine
Nifedipine
Major drug interaction with Statins
Simvastatin
Minor drug interaction with Statins
Atorvastatin
Minor interaction drugs with immunosuppressants
Cyclosporin
Tacrolimus
Two ways drugs are excreted
Renale
Biliary
What factor effect renal excretion of drugs
pH
When are weak bases cleared faster
If urine is acidic
When are weak acids cleared fastest
Urine is alkaline
Name three weak acid drugs
Aspirin
Ibuprofen
Warfarin
Name there weak bases
Amphetamine
Atropine
Diazepam
Salbutamol
Three characteristics of pharmacodynamics
Receptor based
Signal transduction (beta adrenergic receptors)
Physiological systems
How do we avoid drug interactions
- Rational prescription
- BNF
- Ward pharmacist
- Internet
- Medicines information service
