AChE inhibitors Flashcards

1
Q

What are the indications of AChE inhibitors?

A

Monotherapies for managing mild to moderate Alzheimer’s disease

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2
Q

What are the names of the different AChE inhibitors available?

A

Donepezil

Galantamine

Rivastigmine

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3
Q

What is the usual dose of donepezil prescribed?

A

Initially 5mg OD at bedtime

Increased if tolerated and necessary to a max of 10mg daily after 1 month

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4
Q

What is the usual dose of galantamine prescribed?

A

Most people = 8mg capsule OD for 4 weeks, then 16mg OD for at least 4 weeks

Maintenance dose is 16-24mg OD

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5
Q

What is the dose of galantamine prescribed for those with hepatic impairment?

A

Initially 8mg on alternate days, preferably in the morning, for 7 days

Then 8mg OD for 4 weeks

Daily dose should not exceed 16mg

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6
Q

What is the usual oral dose of rivastigmine prescribed?

A

Initially 1.5mg BD

Increased in steps of 1.5mg BD at intervals of at least 2 weeks according to response and tolerance up to a max of 6mg BD

If Tx is interrupted for more than several days, oral rivastigmine should be re-titrated from 1.5mg BD

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7
Q

What is the usual transdermal dose of rivastigmine prescribed?

A

Initially 4.6mg/24 hours patch - applied to clean, dry, non-hairy, non-irritated skin on the back, upper arm or chest

Should be removed after 24 hours

After at least 4 weeks, if well tolerated, the dose should be increased to the usual maintenance dose of 9.5mg/24 hours patch daily

After a further 6 months, if well tolerated and cognitive deterioration or functional decline are demonstrated, the dose can be increased to 13.3mg/24 hours patch daily (should be done with caution in people who weigh < 50kg)

If Tx is interrupted for more than 3 days, transdermal rivastigmine should be re-titrated from a 4.6mg/24 hours patch

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8
Q

What are the contraindications for donepezil?

A

Hypersensitivity to donepezil hydrochloride, piperidine derivatives or any excipients used in the formulation

Pregnancy and breastfeeding

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9
Q

What are the contraindications for galantamine?

A

Hypersensitivity to galantamine or any of the excipients

Severe renal impairment (eGFR < 9mL/min/1.73 m^2)

Severe hepatic impairment (Child-Pugh score > 9)

People who have both significant renal and hepatic dysfunction

Urinary outflow obstruction

GI obstruction

During recovery from bladder or GI surgery

Pregnancy and breastfeeding

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10
Q

What are the contraindications for rivastigmine?

A

Hypersensitivity to rivastigmine, other carbamate derivatives, or any other excipients

Previous Hx of application site reactions suggestive of allergic contact dermatitis with the rivastigmine patch

Pregnancy and breastfeeding

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11
Q

What are the cautions for AChE inhibitors?

A

Hx of bradycardia, heart block, recurrent unexplained syncope

Concurrent Tx with drugs that reduce heart rate

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12
Q

What are the cautions for donepezil?

A

Sick sinus syndrome or other supraventricular conduction abnormalities

Susceptibility to peptic ulcers including concurrent NSAID use

Asthma and COPD

Hepatic impairment

Concomitant antipsychotic Tx - increased risk of neuroleptic malignant syndrome (NMS)

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13
Q

What are the cautions for galantamine?

A

Renal and hepatic impairment

Cardiac disease (inc. sick sinus syndrome, supraventricular conduction abnormalities, post-MI, unstable angina, new onset AF, second degree HB or greater, congestive heart failure)

Or in those that use meds that significantly reduce heart rate concomitantly e.g., digoxin and beta-blockers

QTc interval prolongation or taking drugs that prolong the QTc interval

Electrolyte disturbances (e.g., hyperkalaemia or hypokalaemia)

Susceptibility to peptic ulcers including concomitant use of NSAIDs

Hx of severe asthma, COPD or pulmonary seizures

Hx of seizures

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14
Q

What are the cautions for rivastigmine?

A

Hepatic impairment

Renal impairment

Gastric or duodenal ulcers (or susceptibility to ulcers)

Sick sinus syndrome or conduction abnormalities

Hx of asthma or COPD

Hx of seizures

Bladder outflow obstruction

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15
Q

What are the common adverse effects of donepezil?

A

N+V

Reduced appetite

Diarrhoea

Fatigue

Headache

Dizziness

Syncope

Abnormal dreams

Hallucinations

Agitation

Aggression

Muscle cramps

Urinary incontinence

Rash

Pruritus

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16
Q

What are the rare adverse effects of donepezil?

A

Extrapyramidal symptoms

Sinoatrial block

AV block

Liver dysfunction (inc. hepatitis)

NMS (if someone develops this, donepezil should be discontinued)

17
Q

What are the common adverse effects of galantamine?

A

Vomiting

N+V

Abdo pain

Diarrhoea

Dyspepsia

Decreased appetite

Weight loss (monitor the patient’s weight)

Bradycardia

HTN

Syncope

Hallucinations

Depression

Dizziness

Tremor

Headache

Fatigue

Malaise

Muscle spasm

18
Q

What are the less common adverse effects of galantamine?

A

Retching

Dehydration

Hypotension

Flushing

Palpitation

Arrhythmias

First-degree AV block

Taste disturbance

Paraesthesia

Seizures

Hypersomnia (increased sleepiness)

Muscular weakness

Blurred vision

Tinnitus

Sweating

19
Q

What are the rare adverse effects of galantamine?

A

Exacerbation of Parkinson’s disease

Hepatitis

Serious skin reactions (galantamine should be stopped at the first appearance of a skin rash)

20
Q

What should you warn patients on galantamine and their carers about?

A

Signs of serious skin reactions inc.
- Stevens-Johnson syndrome
- erythema multiforme
- acute generalised exanthematous pustulosis

21
Q

What is Stevens-Johnson syndrome?

A

A rare, serious disorder of the skin and mucous membranes

Usually a reaction to medication that starts with flu-like symptoms, followed by a painful rash that spreads and blisters

Then the top layer of affected skin dies, sheds and begins to heal after several days

It needs to be treated immediately often in ITU

22
Q

What are the common adverse effects of rivastigmine?

A

N+V

Dyspepsia

Anorexia

Weight loss

Abdo pain

Bradycardia

Dizziness

Headache

Drowsiness

Gait abnormalities

Fall

Malaise

Agitation

Anxiety

Tremor

Insomnia

Parkinsonism

Syncope

Skin reactions

UTI

Urinary incontinence

Sweating

23
Q

What are the less common adverse effects of rivastigmine?

A

AF

AV block

Depression

Aggression

24
Q

What are the rare adverse effects of rivastigmine?

A

EPS

Gastric and duodenal ulceration

Pancreatitis

Angina

Seizures

25
Q

What are the frequency unknown adverse effects of rivastigmine?

A

Dehydration

Hallucinations

Hepatitis

Restlessness

Sick sinus syndrome

Tachycardia

HTN

26
Q

What effect does AChE inhibitors have on the ability to drive?

A

A minor or moderate influence on the ability to drive (esp in the 1st weeks after starting Tx or when the dose increases)

AChE inhibitors can cause fatigue, dizziness, sleepiness and muscle cramp and can induce syncope or delirium

Routinely assess the person’s ability to drive

27
Q

What drugs can interact with AChE inhibitors?

A

Antimuscarinic drugs (e.g., TCAs) - antagonise the effects of AChE
- using 2 or more antimuscarinic drugs together can increase adverse effects (e.g., dry mouth, urine retention, and constipation) and can cause confusion in the elderly

Antipsychotics (e.g., olanzapine) - using together with AChE inhibitors increases risk of NMS
- if this happens stop Tx

Beta-blockers (e.g., atenolol) or other bradycardia agents (e.g., CCB, class III antiarrhythmics) - if concurrent is necessary be alert for bradycardia

28
Q

What are the specific drug interactions for donepezil?

A

CYP3A4 inhibitors e.g., ketoconazole and possible itraconazole and erythromycin and CYP2D6 inhibitors e.g., quinidine and possibly fluoxetine = inhibit donepezil metabolism

Liver enzyme inducers e.g., rifampicin, phenytoin, carbamazepine and alcohol = reduced plasma levels of donepezil

29
Q

What are the specific drug interactions for galantamine?

A

CYP3A4 inhibitors e.g., ketoconazole and erythromycin and CYP2D6 inhibitors e.g., quinidine and fluoxetine = increased plasma [galantamine]

30
Q

What are the specific drug interactions for rivastigmine?

A

Metoclopramide
- concurrent use of rivastigmine and metoclopramide could increase the risk of EPS adverse effects
- be alert for movement disorders and signs of NMS

31
Q

Sources

A

https://cks.nice.org.uk/topics/dementia/prescribing-information/acetylcholinesterase-inhibitors/

https://go.drugbank.com/categories/DBCAT000815

https://www.nice.org.uk/guidance/NG97/chapter/Recommendations#pharmacological-management-of-alzheimers-disease

https://www.nhs.uk/medicines/donepezil/