Drugs and Polypharmacy Flashcards
What is polypharmacy?
Polypharmacy = taking 5 or more medications, but starting to mean even 1 drug inappropriately prescribed (basically taking many drugs at once)
What are complications of polypharmacy?
- Adverse drug reactions
- Then the complications of this – falls, cognitive loss, delirium, dehydration, incontinence, depression, loss of functional capacity, poor QoL
Describe the relationship between ADRs and polypharmacy?
What are some common iatrogenic drug reactions?
- Confusion, dry mouth, constipation, blurred vision, urinary retention and hypotension
- Problem is these side effects often dismissed as ‘old age’
- Drugs given to counteract effects of other drugs
How many prescriptions does the typical 85 year old take, why?
Typical 85 year old takes 8-9 prescriptions and 2 OTC drugs at once due to:
- More acute and chronic disease
- More doctor visits
- Healthcare provider factors for polypharmacy – no med review on regular basis, presumes that patient wants meds, prescribes without sufficiently investigating clinical case, following guidelines that leads to drug to drug interactions between management for different diseases, ordering automatic refills
What are some healthcare provider factors for polypharmacy?
- Healthcare provider factors for polypharmacy – no med review on regular basis, presumes that patient wants meds, prescribes without sufficiently investigating clinical case, following guidelines that leads to drug to drug interactions between management for different diseases, ordering automatic refills
What is pharmacokinetics?
What the body does to the drug
What is pharmacodynamics?
What the drug does to the body
Describe changes to pharmacokinetics in older age?
- Absorption
- Rate of absorption is changed but not the extent from GI tract
- Causing delayed onset of action
- Distribution
- Body composition changes
- Reduced muscle mass
- Increased adipose tissue – increased volume distribution (Vd), increased half life (T1/2), increased duration of action for fat soluble drugs
- Reduced body water – decreased Vd, increased serum levels for water soluble drugs
- Protein binding changes
- Decreased albumin – decreased binding, increased serum levels of acidic drugs
- Increased permeability across BBB
- Body composition changes
- Metabolism
- Hepatic metabolism affected by decreased liver mass and decreased liver blood flow
- Consequences
- Toxicity due to reduced metabolism/excretion
- Reduced first pass metabolism – increase in bioavailability of some drugs, but decreased bioavailability of prodrugs
- Excretion
- Renal function decreases with age
- Reducing clearance and increases half-life of many drugs causing toxicity
What are changes to absorption in old age?
- Rate of absorption is changed but not the extent from GI tract
- Causing delayed onset of action
What are changes to distribution in old age?
- Body composition changes
- Reduced muscle mass
- Increased adipose tissue – increased volume distribution (Vd), increased half life (T1/2), increased duration of action for fat soluble drugs
- Reduced body water – decreased Vd, increased serum levels for water soluble drugs
- Protein binding changes
- Decreased albumin – decreased binding, increased serum levels of acidic drugs
- Increased permeability across BBB
What are changes to metabolism in older age?
- Hepatic metabolism affected by decreased liver mass and decreased liver blood flow
- Consequences
- Toxicity due to reduced metabolism/excretion
- Reduced first pass metabolism – increase in bioavailability of some drugs, but decreased bioavailability of prodrugs
What are changes to excretion in older age?
- Renal function decreases with age
- Reducing clearance and increases half-life of many drugs causing toxicity
What are consequences of increased adipose tissue on distribution of drugs?
- Increased adipose tissue – increased volume distribution (Vd), increased half life (T1/2), increased duration of action for fat soluble drugs
