Introduction to Geriatric Pharmacology Flashcards
What is geriatrics?
This is a branch of medicine that focuses on the health care of elderly people, generally those aged 65 and above.
What are some significant changes that occur in old age?
◾ Changes in normal or age-related physiology
◾ Multiple comorbidities and medications
◾ Financial and lifestyle changes
◾ Altered pharmacological responses
◾ More common adverse reactions
◾ More variable organ functions and responses
Pharmacokinetic changes in the elderly
What are some age associated pharmacologic changes?
GFR, cardiac index and maximal breathing capacity decline with age.
Pharmacokinetic changes in the elderly
What are some changes that affect absorption of drugs in the elderly?
◾ decreased bowel surface area
◾ decreased rate of gastric emptying
◾ increase in gastric pH
◾ reduced gastrointestinal motility
◾ reduction of blood flow
◾changes in gastric flora
Pharmacokinetic changes in the elderly
Distribution changes in the elderly
◾ Changes in blood flow
◾ Changes in plasma protein binding e.g decreased albumin levels
◾ Reduction in total body water
◾ Reduced lean body mass
◾ Increase in fat as percentage of body mass
◾ Increase in α-acid glycoprotein which binds basic drugs
Pharmacokinetic changes in the elderly
Drug metabolism changes in the elderly
◾ Changes in hepatic metabolism e.g. decreased liver size and blood flow, reduced activity of liver enzymes e.g. cytochrome P-450 enzymes. These changes may result in increased sensitivity to drugs.
◾ Genetic influences on liver enzymes
◾ Influences of smoking, liver disease, alcohol nutritional status and influence of other drugs
Pharmacokinetic changes in the elderly
Drug excretion changes in the elderly
Ageing causes reduced renal function; 30-35% reduction in glomerular filtration and renal blood flow. This tends to result in prolongation of half-life of many drugs.
Pharmacodynamic changes
◾ Elderly more sensitive to some sedative hypnotics and analgesics
◾ Changes in some receptors with age e.g. decreased responsiveness to β-adrenoceptor stimulants and β-adrenoceptor antagonists
◾ Drug-drug interaction important in patients who have high likelihood of polypharmacy
How can ADRs be avoided in the elderly?
◾ Possibly use non-pharmacological approach or physical therapy
◾ Lowest effective and feasible dose
◾ Avoid multi-drug regiment wherever possible and reduce number of pills
◾ Regular interventions
◾ Frequent auditing of prescriptions
◾ Making sure that the care-taker understands the medications and disease status
