Drugs and Polypharmacy Flashcards

Question

How are water soluble drugs effected in the elderly?

Answer 1

Water soluble drugs tend to experience a reduction in Vd, resulting in higher serum levels. This can be found in the case of theophylline, atenolol, propranolol and hydrochlorthiazide.

Answer 2

Acidic drugs such as cimetidine, furosemide, NSAIDs and sulphonylureas, diazepam, salicyic acid are bound by serum albumin and will be affected. Higher protein bound drugs such as warfarin and phenytoin chlorpropamide, propranolol and quinidine are also likely to be affected. Theoretically, a reduction in albumin would mean there is a greater concentration of unbound acidic drugs in the plasma. Predisposing patients to risk of adrs

Answer 3

An increase in permeability across the blood brain barrier allows drugs to be more readily distributed in the CNS.

Answer 4

Digoxin, although water-soluble has a high Vd. This is due to widespread distrubution into the muscle. The reduction in muscle mass in older people means there is a significant reduction digoxins Vd. The clinical consequence of this is that the loading dose has to be substantially reduced in the elderly. Drugs with a low Vd such as warfarin is not widely distributed. Those with large Vd e.g. digoxin, amiodarone are extensively distributed.

Answer 5

Hepatic metabolism is affected by: - Decreased liver mass - Decreased liver blood flow

Answer 6

Consequences > Toxicity due to reduced metabolism/excretion > Reduced first pass metabolism - ↑ in bioavailability with some drugs e.g. propranolol - Can cause ↓ bioavailability of pro-drugs e.g. enalapril

Answer 7

Renal function decreases with age Reduces clearance and increases half-life of many drugs leading to toxicity

Answer 8

> Increased sensitivity to particular medicines > Due to: - Change in receptor binding - Decrease in receptor number - Altered translation of a receptor initiated cellular response into a biochemical reaction. > Examples: diazepam (↑ sedation), warfarin (↑ anti-coagulation)

Answer 9

Where possible, be clear about the diagnosis to avoid prescribing a drug to manage an adverse effect Consider whether drug therapy is the best therapeutic action Lower doses (or reduced frequency of administration) are generally needed Think about whether the drug causes particular problems in elderly patients Check whether a lower dose is recommended in the elderly: start at the lowest dose and titrate up slowly (‘start low, go slow’) Review the new drug and check whether it is achieving its aim Review all prescriptions regularly and stop any medicines that are not beneficial Try to keep regimens as simple as possible Consider compliance issues which elderly patients in particular may experience Elderly patients should not be denied proven beneficial medicines on the basis of age But bear in mind that clinical trials are often performed in a younger population which may mean that benefits do not translate to an older age group

Answer 10

> Beers’ criteria - List of ‘inappropriate’ drugs for older people - Updated occasionally but many weaknesses > START-STOPP criteria (O’Mahony et al) - Advice on medical optimisation - A lot to remember, so mostly research tool > NHS Scotland Polypharmacy Guidance

Answer 11

Discontinued

Answer 12

Some evidence that it is safe and/or beneficial to stop antihypertensives, benzodiazepines, antipsychotics

Answer 13

Sedatives problematic - Increased effects of benzodiazepines = Falls, confusion

Answer 14

Increased adverse effects = Postural hypotension, stroke, confusion, movement disorders

Answer 15

Less effective, more dangerous?

Answer 16

> More sensitive to effects, lower doses needed | > Pethidine and tramadol may be less useful

Answer 17

Increased adverse effects > Renal impairment > GI bleeding

Answer 18

Increased toxicity | Lower doses needed

Answer 19

> Decreased peak effect, but reduced clearance - Abnormal urea and electrolytes > Other issues around continence and mobility > Often inappropriate indication (swollen legs)

Answer 20

> May have exaggerated effects on BP and HR > More likely to be issues with postural hypotension > ACE inhibitors often pro-drugs which may not be metabolised to the active form > Renal adverse effects

Answer 21

> More sensitive to warfarin | > Greater risk from warfarin i.e. GI bleeding, falls

Answer 22

``` Increased adverse effects > Diarrhoea and c. diff infection > Blood dyscrasias (trimethoprim, co-trimoxazole) Delirium (quinolones) > Seizures > Renal impairment (aminoglycosides) ```