Pharmacology - Old Age & Falls Flashcards
Main variables taht affet drug actions in pt’s
Age Genetic factors Immunological factors Disease (esp. when influences drug elimination or metabolism e.g., kidney or liver disease) Drug interactions Ethnicity
Why is age a main variable that affects drug action
Drug elimination is less efficient in older people ∴ many drugs produce a greater and more prolonger effect
Effect of changing body composition with age
Fat contributes a greater proportion to the body mass in the elderly; reduction in the ‘lean’ body mass, as muscle volume is decreased
Results in change in the volume of distribution of the drug
Volume of distribution and body composition
Changes in the relative % of fat and lean tissue change this distribution due to different classes of drugs being attracted to spp tissues
Effect of age on renal she ration of drugs
GFR falls slowly from 20 yrs. Decreases by 25% by 50 and 50% by age 75 assuming no renal disease
Many drugs are cleared by the body via the kidneys
Dogoxin
Used for atrial fibrillation, less widely used since AF affects mainly older pts
What is the renal clean ce of digoxin closely correlated with
Creatinine clearance
Why is eGFR just an estimate of creatinine clearance
Plasma level of creatinine doesn’t directly correlate with the clearance of creatinine by the kidney
Creatinine synthesis in elder
Reduced due to due to reduction in muscle mass, so we need to take that into account when estimating GFR
Drug metabolism and hepatic enzymes
The activity of these hepatic microsomal enzymes declines slowly and variably with age
Increasing half-life with drugs
Benzodiazepine in older vs younger pts
Produces more confusion in elderly compared to young people despite same plasma level
Anti-hypertensives in old vs younger pts
Postural hypotension is much more common with the older pt. on an anti-hypertensive –> increased risk of falls
Why are older pets at greater risk for drug interactions
Comorobidiities –> prescribe a no. diff drugs for one person
What percentage of adverse drug reactions are caused by drug interactions
5-20%
Examples of chronic disease in older pts
Alzheimer disease and other types of dementia Arthritis Asthma Cancer COPD Diabetes Epilepsy Heart disease HTN Mood disorders (depression and anxiety) MS Parkinson’s
Cimomrbidity in HTN
HTN affects > 1 in 4 adults in the UK and prevalence is rising as population ages. A study found that every 2 in 3 HTN pts have a comorbidity
Comorbidity vin diabetes
87% have hen
26% have nephropathy
22% have cardiovascular disease
Why do we need to be able to justify meds precribes and regularly review the,
Due to effects of age on drug metabolism, clearance, side effect profile
Deprescribing
The process of withdrawal of an inappropriate medication, supervised by an HCP with the goal of managing polypharmacy and improving outcomes
How can poly pharmacy cacaos confusion
Confusion about how to take the med, esp. those that need to be taken more than ODS
UK situation on polypharmavy
Prebvalnec is increasing
In Scotland 5/5+ prescriptions doubled and 10/10+ tripled between 1995-2010
Which sex is polypharacy more common in
Female
Poluypharmacy and asymptomatic pts
To prevent future illness
Incentivised in primary care when payments are made under the quality and outcomes framework
When should deprescribing be considered
Med review
During hosp admission
When we need to treat a new condn
