Prescribing In The Elderly Flashcards
What are the 4 principles of drug action:
Absorption
Distribution
Metabolism
Excretion
What environment does acidic drugs absorb? (Eg phenytoin, aspirin, penicillins)
Acidic
What environment do basic drugs absorb in? (Eg diazepam, morphine)
Basic environment
What happens to the pH of stomach as one ages?
Becomes more acidic
What is the protein carrier for acidic drugs?
Albumin
What is the protein carrier for basic drugs?
Alpha 1 acid glycoprotein
How does the ratio of albumin to A-1 Acid glycoprotein differ with age
Older patients have less albumin and more A-1 AG
Why does having more fat, less muscle with aging affect lipophillic drug levels?
Higher volume of distribution
Body is more lipid soluable
More likely to have a long half life if stored in fat
If patient becomes cahexic- there’s a danger of drugs stored in fat being released (can make things like delirium worse)
What are the common drugs with a narrow therapeutic index?
Vancomycin Phenytoin Cyclosporine Carbamazepine Levothyroxine Theophylline Warfarin Lithium Digoxin Gentamicin
What is the main adverse affect with opioids in the elderly?
Constipation
What extra precautions must you take when prescribing steroids to elderly patients?
Bone protection
Measure blood sugars (steroid induced diabetes)
What is the main interaction with levothyroxine?
Calcium interferes with absorption of levothyroxine (beware of times taking the meds)
What are the main interactions with NSAIDs?
Decrease effectiveness of diuretics and antihypertensives
GI haemorrhage risk
Decline in GFR
What is the interaction between opioids and benzodiazepines?
Impairs psychomotor function (GABBA-A mediated reaction)
Falls/confusion
What patients are at risk of adverse drug reactions?
Recent hospital discharge Poly pharmacy Multiple prescribers Impaired cognitive status Low TI drugs Common side effect drugs Taking lots of OTC or complementary meds Nursing home patients
