Tauklarify

Tauklarify is used for positron emission tomography (PET) imaging of the brain in adults with cognitive impairment who are being evaluated for Alzheimer's disease, to identify patients with tau neurofibrillary tangle (NFT) pathology. It is given as a single injection into a vein about 90 minutes before the PET scan, and the scan itself takes about 20 minutes.

Tauklarify is not a treatment for Alzheimer's disease. It is a radioactive diagnostic drug (also called a radiotracer or imaging agent) that helps make one of the changes in the brain associated with Alzheimer's disease visible on a scan.

Tauklarify (florquinitau F 18) works by attaching to clumps of a protein called tau. In Alzheimer's disease, tau builds up inside brain cells and forms tangles known as neurofibrillary tangles, which are one of the two changes needed for a neuropathological diagnosis of Alzheimer's disease (the other is amyloid beta plaque). Florquinitau F 18 crosses the blood-brain barrier and collects in areas of the brain that contain tau tangles. Because the tracer is labeled with fluorine-18, a radioactive form of fluorine, these areas show up as increased signal on a PET scan. A trained reader then classifies the scan as positive or negative for tau NFT pathology based on the pattern and intensity of signal in the medial temporal lobe and the neocortex.

Tauklarify received FDA approval on August 14, 2026. It is also known in the research literature as MK-6240.

• Tauklarify is given by a healthcare provider in a facility licensed to handle radioactive drugs. You do not take it at home.
• You will be asked to drink water before the injection so that you are well hydrated.
• Imaging begins about 90 minutes after the injection. You lie on your back with your head positioned so that the whole brain, including the cerebellum, is in the scanner's field of view. Tape or a soft head restraint may be used to help you keep still.
• The PET scan takes about 20 minutes.
• After the scan, keep drinking fluids and empty your bladder often to help clear the tracer from your body.
• Your scan is interpreted by a reader trained in Tauklarify image interpretation, who classifies it as positive or negative for tau NFT pathology.

Avoid tobacco smoking and other CYP1A2 inducers for at least 7 days before your Tauklarify scan.

Florquinitau F 18 is broken down in the body by an enzyme called CYP1A2. Medicines and substances that speed up this enzyme, including tobacco smoke, can lower the amount of tracer that reaches the brain and reduce the signal on the scan, which can make the images harder to interpret. Smoking and any medicines that were paused can be restarted once imaging is complete.

Talk to your healthcare provider before stopping any prescribed medicine.

Risk of misdiagnosis in patients being evaluated for Alzheimer's disease

A negative Tauklarify scan does not necessarily rule out tau NFT pathology, and a positive Tauklarify scan does not necessarily confirm it. Further evaluation may be needed if uncertainty remains.

Tauklarify was studied mainly in people at the two ends of the spectrum: people who were cognitively unimpaired and amyloid beta PET-negative, and people who were cognitively impaired and amyloid beta PET-positive. The scan may be less accurate in people at earlier stages of tau pathology.

Scan results are one piece of information and are interpreted alongside a person's symptoms, examination, and other tests.

Radiation risk

Tauklarify adds to a person's overall long-term cumulative radiation exposure, and cumulative radiation exposure is associated with an increased risk of cancer. The whole-body effective radiation dose from the recommended 185 MBq (5 mCi) dose is estimated at about 5.4 mSv. If a PET/CT scan is performed, the CT portion adds further radiation exposure. To reduce exposure, people are advised to:

• drink water before the injection to be well hydrated
• keep drinking fluids after the injection
• empty the bladder often after the scan.

Healthcare providers handle Tauklarify using radiation shielding and protective equipment to limit exposure for both the patient and staff.

Before you receive Tauklarify, tell your healthcare provider about all of your medical conditions, including if you:

• smoke or use tobacco, or take any medicine that is a CYP1A2 inducer. These need to be stopped at least 7 days before your scan because they can lower the amount of tracer signal in the brain and make the images harder to interpret. See "What should I avoid?"
• are pregnant or plan to become pregnant. There are no data on the use of Tauklarify during pregnancy. All radiopharmaceuticals have the potential to cause harm to an unborn baby depending on the stage of pregnancy and the radiation dose. Tauklarify also contains ethanol (up to 0.789 grams per dose), and ethanol exposure during pregnancy is associated with fetal harm, including effects on brain development and intellectual development. There is no established safe level of ethanol use during pregnancy. Your healthcare provider will discuss the potential risks with you before the scan.
• are breastfeeding or plan to breastfeed. It is not known whether florquinitau F 18 passes into breast milk. To limit radiation exposure to a breastfed infant, breastfeeding should be temporarily stopped, and breast milk should be pumped and discarded for at least 4 hours after Tauklarify is given.

Tauklarify has not been studied in children, and its safety and effectiveness in children have not been established.

The safety and effectiveness of Tauklarify have not been established for the evaluation of tauopathies other than Alzheimer's disease (non-Alzheimer's disease tauopathies).

Common side effects

Side effects are uncommon. The most common side effects of Tauklarify are:

• headache
• nausea
• injection site reactions, including injection site rash, discomfort, and injury
• dizziness
• abdominal discomfort or abdominal pain.

These are not all the possible side effects of Tauklarify. Call your doctor for medical advice about side effects. You may report side effects to Cerveau, a Lantheus company, at 1-800-362-2668, or to the FDA at 1-800-FDA-1088.

FDA approval for Tauklarify was based on two blinded read studies (Study 1 and Study 2) that analyzed Tauklarify PET images from more than 500 people who took part in three clinical trials. Participants included people with mild cognitive impairment, people with mild Alzheimer's disease dementia, and people with no cognitive impairment. Each scan was read by independent readers who were trained in image interpretation and who did not know the person's clinical information or amyloid beta PET result. Scans were compared against a reference standard based on cognitive status and amyloid beta PET findings.

• In Study 1 (279 people), positive percent agreement (how often a positive scan matched a positive reference standard) ranged from 80% to 88% across the five readers, and negative percent agreement ranged from 98% to 99%.
• In Study 2 (338 people), positive percent agreement ranged from 68% to 82%, and negative percent agreement ranged from 93% to 99%.
• Readers agreed with each other closely in both studies (generalized Fleiss' kappa of 0.92 in Study 1 and 0.86 in Study 2, where 1.0 is perfect agreement).

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

Your body clears florquinitau F 18 using a liver enzyme called CYP1A2. Anything that speeds this enzyme up, known as a CYP1A2 inducer, breaks the tracer down faster, so less of it reaches your brain. That weakens the signal on your scan and can make the images harder to read.

Avoid CYP1A2 inducers for at least 7 days before your Tauklarify scan. Examples of CYP1A2 inducers are:

• smoking. The compounds responsible are produced by burning, not by nicotine itself, so avoid: cigarettes, cigars, pipes, and smoked cannabis. Nicotine patches, gum, and lozenges do not have this effect.
• rifampin (an antibiotic used for tuberculosis)
• carbamazepine, phenytoin, phenobarbital, and primidone (used for seizures)
• ritonavir (used for HIV)
• teriflunomide (used for multiple sclerosis)
• omeprazole, esomeprazole, and lansoprazole (proton pump inhibitors used for reflux)
• modafinil (used for excessive sleepiness)
• St. John's wort (a herbal supplement).

This is not a complete list. Know the medicines you take. Keep a list of them to show your healthcare provider and pharmacist when you get a new medicine.

Tauklarify is handled and stored by the nuclear pharmacy or imaging facility, not by patients.

Active ingredient: florquinitau F 18 (up to 2 mcg of florquinitau per mL)

Inactive ingredients: ascorbic acid (5 mg to 15 mg per mL), ethanol (up to 10% v/v) in 0.9% sodium chloride injection, and hydrochloric acid added to adjust pH.