Medicines - Older People Flashcards
State 2 changes that occur with ageing.
Progressive loss of functional capacity e.g. renal, hepatic, cardiac, respiratory. Changes in response to receptor stimulation. Reduction in body water, increase in fat content.
What is pharmacokinetics?
What the body does to the drug e.g. absorption, distribution, metabolism.
What is the formula for the volume of distribution?
Total amount of drug in the body divided by the total drug concentration.
Why is increased total body fat dangerous?
Increases in the Vd for fat soluble drugs, increases half-life and increases toxicity.
Why is decreased total body water dangerous?
Decreases Vd for water soluble drugs, means it’s more concentrated so it increases toxicity.
Why is a decrease in serum albumin (protein) dangerous?
Drugs highly bound to plasma protein, increase its drug concentration and increase its toxicity.
What causes a decrease in serum albumin (protein)?
Frailty. Malnutrition. Post-surgery renal impairment.
What hepatic changes occur during ageing?
Hepatic flow decreases. Size of liver decreases. Reduced liver enzyme activity.
What happens to hepatic drug clearance during ageing, and why is this dangerous?
Drug clearance reduced. Increases toxicity.
What happens to the renal system during ageing?
Drug clearance is excretion. Increases toxicity.
What two things are used to determine correct dose in ageing?
Glomerular Filtration Rate (GFR). Creatinine Clearance (CC).
What is the index where small differences in dose/blood concentration may lead to dose/blood concentration dependence?
National Therapeutic Index (NTI).
Which drugs should you avoid prescribing (nephrotic drug - high on NTI)?
NSAIDs e.g. aspirin.
celecoxib, diclofenac, ibuprofen, indomethacin. Angiotensin-converting enzyme inhibitor (ACEI) e.g. Benazepril, Captopril, Enalapril.
What is meant by pharmacodynamics?
What the drug does to the body.
State 2 organ/system changes during ageing.
Reflex tachycardia e.g. postural hypotension. Poor postural control - falls. Structural/neurochemical changes in CNS - reduced dopamine. Impaired thermoregulation - hypothermia. Reduced visceral muscle function - constipation, urinary incontinence.
