Drugs in health and disease 2 Flashcards by Adele Atkins

What percentage of the population are over 65s?

13%

How well did you know this?

Not at all

Perfectly

What percentage of prescriptions are for over 65s?

30-40%

How well did you know this?

Not at all

Perfectly

How many times more common are drug reactions in the elderly?

2-3

How well did you know this?

Not at all

Perfectly

What does an increased number of drugs cause?

Increased reactions
Increased adverse effects
Decreased adherence

How well did you know this?

Not at all

Perfectly

Define pharmacodynamics

The effect the drug has on the body

How well did you know this?

Not at all

Perfectly

Describe pharmacokinetics

The way the body affects the drug over time

How well did you know this?

Not at all

Perfectly

List some concepts involved in pharmacokinetics

Absorption
Distribution
Metabolism
Excretion

How well did you know this?

Not at all

Perfectly

Describe drug absorption in the elderly

Reduced saliva
Reduced gastric acid 
Decreased GI motility 
Reduced surface area for absorption 
Reduced splanchnic blood flow

Overall effect:↓ rate of absorption & ↑ time to steady state

How well did you know this?

Not at all

Perfectly

When should levodopa be taken and why?

Not at mealtimes

Competes with nutrients

How well did you know this?

Not at all

Perfectly

Describe how bisphosphonates should be taken

On an empty stomach
Sitting up
30 mins before food

How well did you know this?

Not at all

Perfectly

What is the volume of distribution?

Hypothetical volume obtained if all the drug was in the blood

How well did you know this?

Not at all

Perfectly

What is the equation for the volume of distribution?

Vd = Amount of drug in body / Concentration in plasma

How well did you know this?

Not at all

Perfectly

What does Vd affect?

Half life and duration of action

How well did you know this?

Not at all

Perfectly

Describe how drug distribution is affected in the elderly

Decreased lean body mass (muscle), Decreased volume of distribution for drugs that distribute into muscles, Increased plasma concentration of drugs that distribute into muscles

Increased body fat, increased volume of distribution for fat soluble drugs, increased half life

Decreased body water, decreased volume of distribution of water soluble drugs, increased plasma concentration

Albumin decreased by 15-25% so drug binding capacity is reduced which increases the free drug

How well did you know this?

Not at all

Perfectly

Describe the presentation of digoxin toxicity

Cardiac - heart block, bradycardia, junctional tachycardia

Psychiatric - delirium, fatigue, malaise, confusion and dizziness

Visual - blurred or yellow green vision, halos, double vision, photophobia

Gastrointestinal - anorexia, vomiting, nausea, diarrhea, abdominal pain

How well did you know this?

Not at all

Perfectly

What are normal digoxin values?

1-2ng/ml

How well did you know this?

Not at all

Perfectly

Which patient has the more serious cardiotoxicity?

a) Normal dioxin levels 6hrs post dose with renal insufficiency and severe hypokalemia
b) high digoxin levels and no renal or electrolyte disturbance?

How well did you know this?

Not at all

Perfectly

How is digoxin toxicity treated?

Correction of electrolytes
Withdrawal of drug
If severe - use digoxin specific antibody fragments

How well did you know this?

Not at all

Perfectly

List some fat soluble drugs

Benzodiazepines

Haloperidol

How well did you know this?

Not at all

Perfectly

Give some symptoms of benzodiazepine toxicity

Confusion
Drowsiness
Ataxia
Dependence

How well did you know this?

Not at all

Perfectly

How is benzodiazepine toxicity treated?

IV flumazenil 200mcg
Antagonist
Shorter half life than diazepam so the patient may become resedated

How well did you know this?

Not at all

Perfectly

Name a water soluble drug

Gentamicin

How well did you know this?

Not at all

Perfectly

Name some drugs which bind to albumin

Phenytoin
Warfarin
Propranolol
Diazepam 
Levothyroxine 
Digoxin 
Furosemide

How well did you know this?

Not at all

Perfectly

What conditions depress albumin?

Old age
Heart failure
renal disease
RA
hepatic cirrhosis
Malignancy

How well did you know this?

Not at all

Perfectly

List the sins of phenytoin toxicity

``` Nausea, vomiting Tremor Ataxia Nystagmus Coarse facies Hepatitis ```

What is warfarin highly bound to?

Plasma albumin

What properties does warfarin have?

Narrow therapeutic index | Small volume of distribution

Describe the interaction between aspirin and warfarin

Aspirin can displace warfarin from plasma albumin Displacement of 1-2% bound warfarin doubles or triples the concentration of warfarin and so increases the risk of bleeding.

Give the adverse effects of antiplatelet drugs

Peptic ulcer disease Increased bleeding risk Fluid retention Renal failure

Give the adverse effects of anticoagulants

Bleeding tendency | Interaction with other drugs

Describe liver metabolism in the elderly

Decreased liver size - (30%) Decreased liver blood flow (12-40%) - decreased first pass metabolism Decreased enzymatic activity of CP450 - decreased clearance of drugs and increased half life

Which drugs are metabolised by the liver?

Benzodiazepines, phenytoin, antidepressants, antipsychotics, beta blockers, calcium channel blockers, warfarin, theophylline, NSAIDS, erythromycin

Describe renal excretion in the elderly

Decreased renal size (20%), decreased renal blood flow, decreased renal function

What happens to eGFR with age?

Decreases by 1% each year from the age of 40

The excretion of which drugs is affected by renal function

Any drug which is greater than 60% excreted by the kidneys ``` Digoxin Atenolol Sotalol Lithium Allopurinol Antibiotics ```

How does impaired excretion affect the elderly?

Increased half life and serum plasma

What are the implications for problems in excretion of drugs in the elderly?

Reduce the dose in once daily preparations Increase the dosage interval between more frequently administered drugs

What is the normal 12 hour post dose lithium level?

0.4-0.8 mmol/L

Give some signs of early lithium toxicity?

Tremor, twitching and agitation

Give some intermediate sin of lithium toxicity

Lethargy

Give some signs of late lithium toxicity

Coma, fits, arrhythmia, renal failure

What level of lithium does late lithium toxicity occur at?

>2 mmol/L

What level does early lithium toxicity occur at?

>1.5mmol/L

What is a treatment of late lithium toxicity?

Haemodialysis

How many times more potent is SC morphine than PO?

2 times

Describe the metabolism of morphine in elderly

Phase 2 conjugation reaction Morphine 6 glucuronide 40X more potent Approximately 80% analgesic action derived from morphine 6 glucuronide Renal impairment results in accumulation of metabolite Prolonged effect increases the toxicity

Give the signs of morphine toxicity

``` Nausea Vomiting Constipation Drowsiness Respiratory depression Hypotension ```

How do you treat morphine toxicity?

IV naloxone 400 micrograms

How does ageing affect pharmacodynamics do we think?

Decreased number and affinity of receptors Alterations in 2nd messenger function Alterations in cellular and nuclear responses

Which drug effects are increased in the elderly?

``` Alcohol - sedation and lateral sway Hypotensives - postural hypotension Anticholinergics - central effects increased Warfarin - increased bleeding Increased GI effects of NSAIDs Benzodiazepines - increased sedation ```

Which drug effects are decreased in the elderly?

B1 modulators in cardiac tissue Reduced and delayed bronchodilatory response to beta agonists Calcium channel blocker effect on PR interval decreased

How should elderly patients take their medications?

Upright position with plenty of fluid

Describe how frailty affects ability to take oral medications?

Unable to swallow | Tablets may cause ulceration in the mouth

List the side effects of ACE inhibitors

Dry cough Hypotension Renal failure Potassium sparing

List the side effects of beta blockers

``` Hypotension Confusion Bradycardia Impotence Lethargy ```

List the side effects of calcium channel blockers

Hypotension Negatively inotropic Fluid retention

List the side effects of diuretics

``` Hypotension Hypokalaemia Hyponatraemia Confusion Dehydration ```

List the side effects of traditional antipsychotics

``` Confusion Sedation Parkinsonism Tardive dyskinesia Neuroleptic malignant syndrome ```

Name a traditional antipsychotic

Haloperidol

What can you do to increase compliance of the elderly

Consider cognitive problems – carer to prompt patient with medications Simplify regimes as much as possible to once or twice daily Dossit boxes Consider manual dexterity and vision of the patient Check inhaler techniques Syrups if dysphagia for large tablets

What percentage of hospital admissions are due to adverse drug reactions

15.3%