Leqembi (Lecanemab‑irmb): Uses, Dosage, Side Effects, Cost & Safety Information

Leqembi is an FDA‑approved biologic indicated for adults with mild cognitive impairment due to Alzheimer’s disease or with mild dementia. The active substance is lecanemab‑irmb, a monoclonal antibody that targets beta‑amyloid plaques in the brain.

Boxed warning: Leqembi carries a serious FDA boxed warning for amyloid‑related imaging abnormalities (ARIA). See the “Boxed Warning” section for details.

Note for caregivers: As Alzheimer’s progresses, patients may need assistance understanding treatment information. This overview is written to help caregivers grasp the most important aspects of Leqembi therapy.

How Leqembi Works

Beta‑amyloid accumulation is a hallmark of Alzheimer’s pathology. Clinical studies demonstrated that lecanemab‑irmb reduces amyloid plaques, which can modestly delay cognitive decline in patients with early‑stage disease.

Typical Dosage & Administration

Leqembi is supplied as a liquid solution in single‑dose vials for intravenous infusion and as a pre‑filled autoinjector (Leqembi Iqlik) for subcutaneous injection. The recommended regimen is one dose every two weeks, administered under the supervision of a qualified healthcare professional.

Duration of Therapy

When the treating physician determines that Leqembi is safe and effective, therapy is usually continued long‑term, with periodic reassessment of clinical benefit and safety.

Common Side Effects

Side effects vary with age, comorbidities, and concomitant medications. Frequently reported events include:

• Infusion‑related reactions (e.g., dizziness, rash, nausea)
• Headache
• Transient confusion

Patients should discuss any new or worsening symptoms with their provider promptly.

Boxed Warning – Amyloid‑Related Imaging Abnormalities (ARIA)

ARIA refers to MRI‑detected brain changes such as swelling (edema) or microhemorrhage. Most cases are asymptomatic, but some individuals experience:

• Confusion or dizziness
• Headache
• Nausea
• Seizures
• Visual disturbances

Rarely, ARIA can be life‑threatening. Genetic testing may be recommended to assess individual risk. Baseline MRI and follow‑up scans before the 3rd, 5th, 7th, and 14th infusions are standard practice. If ARIA is detected, treatment may be paused or discontinued.

Precautions & Contraindications

Before initiating Leqembi, disclose your full medical history, including:

• History of intracerebral hemorrhage or bleeding disorders
• Severe renal or hepatic impairment
• Use of anticoagulants or antiplatelet agents

Leqembi’s safety in pregnancy and lactation has not been established; discuss alternative options if you are pregnant, planning pregnancy, or breastfeeding.

Drug Interactions

Leqembi may interact with prescription drugs, over‑the‑counter products, vitamins, herbs, and certain foods. Provide a complete medication list to your physician and pharmacist to avoid adverse interactions.

Cost & Access

Pricing varies by insurance coverage, pharmacy, and administration setting. Patients without insurance may qualify for the Eisai Patient Support savings program. Discuss financial assistance options with your prescriber or pharmacist.

Alternative Alzheimer’s Therapies

Other FDA‑approved agents include:

• Cholinesterase inhibitors: donepezil (Aricept), galantamine, rivastigmine
• NMDA‑receptor antagonist: memantine (Namenda)
• Combination product: donepezil/memantine (Namzaric)

These alternatives may be appropriate depending on disease stage and individual tolerance.

Frequently Asked Questions

Does Leqembi cure Alzheimer’s? No. It is intended to slow disease progression, not reverse existing damage.

Are long‑term side effects known? Clinical trials up to 18 months reported no new safety signals, but long‑term data remain limited due to the drug’s recent approval (2023).

What should I do if I experience ARIA symptoms? Contact your neurologist immediately; imaging may be required, and treatment adjustments will be considered.

Leqembi Images