Drugs and Polypharmacy

Question 1

How does old age affect absorption?

Answer 1

• rate is affected, but extent of absoption not always affected
• delayed onset of action

Question 2

How does old age affect distribution?

Answer 2

• dec muscle mass
• inc adipose tissue
• lipophilic drugs; inc Vd, inc T1/2, inc duration of action
• dec body water
• lipophobic drugs; dec Vd, inc serum levels
• dec albumin
• dec binding, inc serum levels acidic drugs
• inc permeability across BBB

Question 3

How does old age affect metabolism?

Answer 3

Hepatic metabolism:

• dec. liver mass
• dec. liver blood flow
• toxicity from dec. metabolism/excretion
• dec. first pass metabolism

Question 4

How does old age affect excretion?

Answer 4

• renal function dec. with age
• dec. clearance + inc. half-life -> toxicity

Question 5

How does old age affect pharmacodynamics?

Answer 5

• inc. sensitivity to certain medicines

Due to:

• change in receptor binding
• dec. in receptor number
• altered translation of a receptor initiated cellular response into a biochemical reaction