Donanemab (Kisunla)

What it treats

Donanemab is approved by the U.S. Food and Drug Administration for the treatment of Alzheimer's disease in adults with mild cognitive impairment or mild dementia stage of disease, with confirmed amyloid pathology.

It's a disease-targeted treatment, not a symptomatic one. The goal is to slow the slope of decline. It doesn't restore lost function and it doesn't halt the disease. In the pivotal trial (TRAILBLAZER-ALZ 2), it modestly slowed cognitive and functional decline in early Alzheimer's over 18 months. The benefit was larger in people with lower baseline tau burden.

Donanemab isn't used for later-stage Alzheimer's, other dementias (Lewy body, vascular, frontotemporal), or in people without confirmed amyloid pathology.

How it works

Amyloid plaques are a defining pathologic feature of Alzheimer's disease. Donanemab is a monoclonal antibody that recognizes a specific modified form of amyloid found in plaques (N3pG-Aβ). It binds the plaque, tags it for the immune system, and microglia clear it. Amyloid PET scans typically show substantial plaque reduction within months of treatment, and many patients reach a defined "amyloid clearance" threshold.

One distinctive feature: donanemab dosing can be stopped once amyloid PET shows clearance, because the plaque burden has been removed. Trials showed that many patients reach clearance within 12 months, some within 6.

Whether removing plaque changes the clinical course as much as anyone would like is still being worked out. The signal is real but modest. Families weighing this treatment should understand what "slowing decline" means and what it doesn't.

Receptor mechanism (detail)

Donanemab is a humanized IgG1 monoclonal antibody that binds an N-terminal truncated and pyroglutamate-modified form of amyloid beta (N3pG-Aβ) found in established plaques rather than in soluble amyloid. This targeting drives microglia-mediated plaque clearance. The mechanism differs slightly from lecanemab, which targets protofibrils, though both remove amyloid on PET.

Potency and typical dosing pattern

Ranges are typical framework only, not a prescription for any individual.

The FDA-labeled schedule is 700 mg IV every 4 weeks for the first 3 doses, then 1400 mg IV every 4 weeks. Each infusion is given over about 30 minutes.

Confirmation of amyloid pathology (by PET or CSF) is required before the first dose. Baseline MRI is required and is repeated before doses 2, 3, 4, and 7. Extra MRIs are triggered by symptoms or by findings on scheduled scans.

Because donanemab clears amyloid to a defined threshold, treatment can be discontinued once amyloid PET shows clearance. Continuing indefinitely isn't necessary, and this is a genuine difference from open-ended treatment paradigms.

Safety monitoring

• Baseline MRI to rule out microhemorrhages or superficial siderosis that would increase risk.
• MRIs before doses 2, 3, 4, and 7 and any time new neurologic symptoms appear.
• ApoE4 genotyping is recommended before starting. Homozygotes have substantially higher rates of ARIA-E and ARIA-H, including severe events. Careful risk-benefit conversation, and in some cases avoiding treatment, is appropriate.
• Infusion reactions. Usually mild to moderate, manageable with premedication and slower infusion.
• Amyloid PET during treatment to identify when clearance has been reached and dosing can stop.
• Anticoagulation. Concurrent anticoagulation increases risk of macrohemorrhage in the setting of ARIA. Careful review of anticoagulant need before starting.

What to expect

Common side effects

• Infusion reactions (chills, headache, flushing, sometimes rash).
• Headache.
• Fatigue.
• Nausea.
• ARIA on MRI (often asymptomatic; see below).

Serious side effects and warnings

• ARIA-E (amyloid-related imaging abnormalities, edema). Fluid or swelling seen on MRI. Often asymptomatic; when symptomatic can cause headache, confusion, dizziness, nausea, visual changes, gait problems, or seizure. Usually resolves over weeks with holding treatment. Rare severe cases have caused permanent injury or death.
• ARIA-H (amyloid-related imaging abnormalities, hemorrhage). Small microbleeds or superficial siderosis. Usually asymptomatic on scheduled scans. Larger hemorrhages have occurred, especially in ApoE4 homozygotes and in people on anticoagulation.
• ApoE4 homozygotes carry substantially higher ARIA risk. Genotyping and a careful conversation before starting are standard.
• Infusion reactions. Usually mild, occasionally severe.
• Anticoagulation. Increases the risk of serious hemorrhage in the setting of ARIA.
• Deaths from ARIA-related events have been reported. This is a real and clinically important risk to review.

Sexual and relational effects

Sexual side effects aren't a prominent feature of donanemab. The relational picture is the important one. Anti-amyloid therapy asks a lot of a family: monthly infusion visits, MRI schedules, a genotype conversation, and hard trade-offs about a treatment that slows decline modestly rather than reversing it. Care partners often carry most of the coordination. That work deserves acknowledgment.

Weight, appetite, and sleep

No characteristic effect on weight, appetite, or sleep at usual doses. Fatigue after infusions is common and usually settles within a day or two.

Starting and dosing basics

This section is general background, not a dosing instruction for any individual.

Before starting: confirmed diagnosis of early Alzheimer's (MCI or mild dementia due to AD), amyloid confirmation on PET or CSF, baseline MRI, ApoE4 genotype, review of anticoagulation, and a full risk-benefit discussion with the patient (where possible) and family. Blood-based amyloid biomarkers are increasingly used for initial screening, though confirmatory testing with PET or CSF is still standard before treatment.

Infusions are given in a center equipped for MRI monitoring and infusion reaction management. The schedule is 700 mg every 4 weeks for 3 doses, then 1400 mg every 4 weeks. MRIs are scheduled before doses 2, 3, 4, and 7, and any time new symptoms appear.

Missed doses and interactions

A missed infusion is rescheduled with the infusion center. There's no problematic drug interaction list the way there is with small-molecule medications. The most important co-medication conversation is about anticoagulation: warfarin, DOACs, and treatment-dose antiplatelet therapy raise ARIA-related hemorrhage risk and need careful review before starting.

Stopping and tapering

Donanemab doesn't need to be tapered. It's stopped when amyloid PET shows clearance, or when side effects or clinical judgment call for stopping. Once stopped for clearance, the plan is to follow the person clinically and consider re-treatment only if there's a specific reason and amyloid re-accumulation is documented, though re-treatment protocols are still being defined.

If ARIA develops, treatment is held (usually for weeks) and restarted at the same or a reduced dose based on severity and location of findings.

Pregnancy and breastfeeding

Not applicable to the typical patient population. There are no meaningful data.

Cost and generic availability

Donanemab is branded (Kisunla) and expensive. There's no generic version and there won't be one for the foreseeable future (it's a biologic). Medicare coverage for anti-amyloid monoclonal antibodies in patients meeting specific criteria was established with the CMS national coverage determination; commercial coverage varies. Site-of-care requirements, prior authorization, and MRI infrastructure make access uneven.

Common questions

Is this a cure? No. It removes amyloid plaques and modestly slows cognitive and functional decline in early Alzheimer's. It doesn't reverse damage or stop the disease.

How long do I need to be on it? Not indefinitely. Once amyloid PET shows clearance (often 6 to 18 months), treatment can be stopped. Follow-up is clinical.

What's ARIA and how worried should I be? ARIA is brain edema (ARIA-E) or microbleeds (ARIA-H) seen on MRI. Most cases are asymptomatic and caught on scheduled scans. A minority cause symptoms, and rare severe cases have caused permanent injury or death. ApoE4 homozygotes are at higher risk. It's the single most important safety conversation.

Should I get my ApoE4 status checked first? Yes, before starting. Homozygotes have much higher ARIA rates and often shouldn't receive donanemab, or should proceed only after a very careful conversation.

What if I'm already on a blood thinner? Bring that up front. Combined use raises the risk of serious hemorrhage. Some patients pause or change anticoagulation; some don't proceed with donanemab.

Questions to ask your prescriber

• Do I meet criteria (early Alzheimer's, confirmed amyloid, otherwise appropriate)?
• What's my ApoE4 status, and how does that change the risk?
• What's the MRI schedule and what happens if ARIA is found?
• What are we hoping to see, and how will we know it's working?
• When would we plan to stop?

Sources

This guide draws on current prescribing information and public health references. It is reviewed for clinical accuracy and updated as guidance changes, and current as of June 8, 2026.

• U.S. Food and Drug Administration. Donanemab-azbt (Kisunla) prescribing information, approved 2024.
• DailyMed, U.S. National Library of Medicine. Donanemab-azbt.
• Alzheimer's Association. Anti-amyloid treatments and appropriate use recommendations.
• Centers for Medicare and Medicaid Services. National Coverage Determination for anti-amyloid monoclonal antibodies.
• Appropriate Use Recommendations for donanemab published in peer-reviewed dementia journals.