Donepezil and Memantine in Moderate to Severe Alzheimer's Disease (DOMINO-AD)

King's College London

Status and phase: Unknown; Phase 4

Conditions: Moderate to Severe Alzheimer's Disease

Treatments: Drug: Placebo memantine; Drug: Placebo donepezil; Drug: Donepezil; Drug: Memantine

Study type: Interventional

Funder types: Other

Identifiers

NCT00866060

ISRCTN49545035

Eudract 2007-001172-36

2006/123

Details and patient eligibility

About

The trial will examine whether pharmacological treatment with donepezil, memantine or combination of memantine and donepezil is any better than a placebo (dummy) treatment in people with Alzheimer's disease who have reached the moderate to severe stage of illness. Using a double blind design, where neither the investigators nor participants know who is receiving which treatment, participants will be randomly assigned to one of these four treatment groups (donepezil and memantine, memantine only, donepezil only or placebo). In order to keep both the investigators and participants blind to drug allocation a double dummy design will be necessary. This means that each participant will receive 2 treatments - either an active form or placebo of each of the 2 study drugs.

Hypotheses are:

1. Patients with Alzheimer's disease (AD) who continue donepezil beyond the point of transition from moderate to severe dementia continue to show significantly less decline on ratings of cognitive function and activities of daily living over the following 12 months than those discontinuing donepezil.
2. Patients with AD who change to memantine therapy in place of donepezil at the point of transition from moderate to severe dementia show significantly smaller decline on ratings of cognitive function and activities of daily living over the following 12 months than those who receive placebo.
3. Patients given the combination of memantine and donepezil at the point of transition from moderate to severe dementia show significant additive or synergistic benefits on measures of activities of daily living and cognitive function after 12 months compared to those patients continuing on either drug as a single treatment.

Full description

This trial will involve the withdrawal of drug participants that are currently on (donepezil) and in arm 4, the participant will only be on placebo treatment. It is important to include this arm of the study as a key objective in looking at the benefit of continuing donepezil and therefore a placebo arm should be present as a comparator. To reduce the risk to participants of withdrawing donepezil too early in their illness, an inclusion criteria is that the participant is at a stage in their disease whereby the prescribing clinician feels a change in drug prescription may be appropriate.

Enrollment: 800 estimated patients

Sex: All

Volunteers: No Healthy Volunteers

Inclusion criteria

Participants will be patients who meet NINCDS-ADRDA criteria for probable or possible Alzheimer's disease (McKhann et al, 1984). In addition they will meet all of the following criteria:

1. SMMSE = 5 to 13 (13 chosen as NICE threshold of 10 plus 1 SD on SMMSE score)
2. Continuously prescribed donepezil for at least 3 months
3. Maintained on 10mg donepezil in previous 6 weeks.
4. No changes in prescription of any psychotropic (antipsychotic, antidepressant, benzodiazepine) medication in previous 6 weeks.
5. Prescribing clinician considers (based on NICE guidance, discussions with patient and carer and clinical judgement) that change of drug treatment (i.e. stop donepezil or introduce memantine) may be appropriate.
6. Patient is community resident and has family or professional carer or is visited on at least a daily basis by carer.
7. Patient agrees to participate if considered capable (see section 7.5)
8. Main carer (informal or professional) consents to their own involvement and the patient's involvement -

Exclusion criteria

To maximise the generalisability of the study data, exclusions will be kept to a minimum. These will include:

1. Patient has severe, unstable or poorly controlled medical conditions apparent from physical examination or clinical history.
2. Patient is already prescribed memantine.
3. Patient is unable to take trial medications because of contra-indications or previous adverse or allergic reactions.
4. Patient is involved in another clinical trial.
5. Clinician considers patient would not be compliant with trial medication. -

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Factorial Assignment

Masking: Quadruple Blind

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800 participants in 4 patient groups, including a placebo group

1

Active Comparator group

Description:

10mg donepezil plus 20mg memantine Participants in this arm will continue with their current donepezil 10mg/day regimen and immediately commence active memantine at a dose of 5mg per day, increasing in 5mg increments weekly until 20mg per day is achieved from week 4 onwards

Treatment:

Drug: Memantine

Drug: Donepezil

2

Placebo Comparator group

Description:

Placebo donepezil plus 20mg memantine Participants in this arm will immediately commence active memantine at a dose of 5mg per day, increasing in 5mg increments weekly until 20mg per day is achieved from week 4 onwards. Donepezil dose will be reduced to 5mg daily in weeks 1 to 4 and replaced with placebo donepezil in week 5.

Treatment:

Drug: Memantine

Drug: Placebo donepezil

3

Placebo Comparator group

Description:

10mg donepezil plus placebo memantine Participants in this arm will continue with their current donepezil 10mg/day regimen and immediately commence placebo memantine.

Treatment:

Drug: Placebo memantine

Drug: Donepezil

4

Placebo Comparator group

Description:

Placebo donepezil plus placebo memantine Participants in this arm will immediately commence placebo memantine dose escalation and will switch to donepezil 5mg daily in weeks 1 to 4, and replaced with placebo donepezil in week 5.

Treatment:

Drug: Placebo donepezil

Drug: Placebo memantine