Prescribing for Alzheimer's disease

Alzheimer's disease is the commonest form of dementia. Dementia affects one in 20 people over the age of 65 and one in five over the age of 80. As definitive diagnosis is made by demonstration of pathological features in brain tissue, diagnostic criteria (e.g. ICD10, DSM IV, or NINCDS/ADRDA) have been developed to provide an assessment tool to assist diagnosis.

Acetylcholine (ACh) is a neurotransmitter that appears depleted in the brains of patients with Alzheimer's disease. Acetylcholinesterase (AChE) inhibitors elevate the levels of ACh by inhibiting an enzyme responsible for its breakdown leading to an improvement in symptoms for some patients though not altering the outcome of the disease.

See: NICE TA217: Alzheimer's disease - donepezil, galantamine, rivastigmine and memantine (March 2011)

For further details see Mental Health Prescribing Forum Prescribing Guideline PG15- Pharmacological Management of Alzheimer's Dementia (AD)

Indications

NICE has issued the following guidance (TA217):

  • The three AChE inhibitors donepezil, galantamine and rivastigmine are recommended as options for managing mild to moderate Alzheimer's disease
  • Memantine is recommended as an option for people with:
    • moderate Alzheimer's disease who are intolerant of or have a contraindication to AChE inhibitors or
    • severe Alzheimer's disease
  • Combination treatment of Alzheimer's disease with an AChE inhibitor and memantine is not recommended
  • If prescribing an AChE inhibitor (donepezil, galantamine or rivastigmine), start treatment with the drug with the lowest acquisition cost. However, if this is not suitable, an alternative AChE inhibitor can be prescribed

Diagnosis

The severity of Alzheimer's disease can be assessed using several methods. Severity is frequently defined by Mini Mental State Examination (MMSE) score:

  • mild Alzheimer's disease: MMSE 21–26
  • moderate Alzheimer's disease: MMSE 10–20
  • moderately severe Alzheimer's disease: MMSE 10–14
  • severe Alzheimer's disease: MMSE less than 10

Assessing the severity of Alzheimer's disease and the need for treatment should not rely solely on cognition scores in circumstances in which it would be inappropriate, for example with patients with learning disabilities or language differences.

The specialist should seek carer's views on patient's condition at baseline and at any follow-up

Only specialists in the care of patients with dementia should make diagnosis of Alzheimer's disease and assess whether the individual is suitable for treatment and initiate treatment where appropriate.

Initiating therapy

The specialist should discuss with the patient and their carer(s) the benefits, side effects, frequency of dosing and monitoring requirements of their treatment.

The specialist should choose most appropriate drug, initiate treatment, prescribe and monitor the patient until the dose is stabilised. Memantine should not prescribed in combination with donepezil, rivastigmine or galantamine.

The specialist should specify any necessary monitoring and review dates at clinically relevant time intervals for both the GP and specialist team and any other patient specific information.

There should be a suitable person identified to ensure concordance with treatment (e.g. relative or other carer), either by the specialist or GP. They should also make the carer aware of the nature of the effect of treatment and that it could be stopped if the patient does not clearly benefit from the drug treatment.

Ongoing responsibilities

Treatment should be prescribed by the GP after communication with specialists regarding the need for treatment and once the maintenance dose has been established.

For patients initially diagnosed with mild or moderate Alzheimer's disease, the patient should be referred to the specialist if a routine review of progress indicates that the severity of the patient's Alzheimer's disease has progressed to severe. A medication review by the specialist will be required.

The specialist will identify criteria to be used to assess response to treatment using the baseline assessment encompassing cognitive, global and behavioural functioning and assess activities of daily living. Again not relying solely on cognition scores in circumstances in which it would be inappropriate.

Specialist services will provide advice and, if appropriate, undertake a treatment review in response to the following situations:

  • The GP considers that the patient is experiencing side effects from the currently prescribed AChI and would like advice on alternatives or discontinuation
  • Additional neuropsychiatric symptoms or challenging behaviours have arisen and the GP feels that further assessment by secondary care older people's mental health services is warranted

Stopping treatment

Whilst the three cholinesterase inhibitors (donepezil, galantamnine and rivastigmine) are only licensed in the UK for the treatment of mild or moderate dementia, research evidence has shown that they can also have a beneficial effect in patients with a severe dementia as well. Therefore they are usually not stopped until either:

  1. Unacceptable side-effects occur. Though patients often tolerate the gastro-intestinal effect of these drugs better in the later stages of dementia, clinical experience has shown that sometimes if agitation is a problem, stopping these drugs can alleviate this. Review may also be required if bradycardia is a concern. or
  2. The patient's dementia deteriorates to such an extent, or other co-morbidities occur such as terminal illness, that continuing the drug is no longer clinically useful. Treatment should be continued only when it is considered to be having a worthwhile effect on cognitive, global, functional or behavioural symptoms.

These decisions should be discussed with the family / carers and it is good practice to wean the medication off, e.g. reducing the dose by 50% for a month and then stopping. The patient then can be monitored over the next couple of weeks for signs of deterioration and the drug restated if needed, although return to previous level of functioning may not be achieved.

Supporting Information

Please refer to SPC or current BNF for the different products for information on side-effects, cautions and contraindications

Contact details for the Specialist Teams

Dr S Black: 01392 674142 - sarahe.black@nhs.net

Dr A Christopher: 01392 385822 - anthony.christopher@nhs.net

Dr S Harris: 01392 402596 - susie.harris@nhs.net

Dr A Hinton: 01392 404545 - a.hinton@nhs.net

 

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