Class Name(s):

• 28:24.48 Melatonin Receptor Agonists

Pronunciation:

• (tas'' i mel' tee on)

Brand Name(s):

• Hetlioz^®

WHY is this medicine prescribed?

Tasimelteon is used to treat non-24-hour sleep-wake disorder (non-24; a condition that occurs mainly in people who are blind in which the body's natural clock is out of sync with the normal day-night cycle and causes a disrupted sleep schedule) in adults. It is also used to treat nighttime sleep problems in adults and children 3 years of age and older with Smith-Magenis Syndrome (SMS; a developmental disorder). Tasimelteon is in a class of medications called melatonin receptor agonists. It works similarly to melatonin, a natural substance in the brain that is needed for sleep.

HOW should this medicine be used?

Tasimelteon comes as a capsule and as an suspension to take by mouth. It is usually taken without food once a day, 1 hour before bedtime. Take tasimelteon at the same time every night. If you or your child are unable to take tasimelteon around the same time on a given night, skip that dose and take the next dose as scheduled. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take tasimelteon exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Swallow the capsules whole; do not open, crush, or chew them.

If you or your child are taking the suspension, follow these steps to prepare and measure the dose:

1. Remove the tasimelteon bottle, bottle adapter, and oral dosing syringe from the carton.
2. Shake the bottle up and down for at least 30 seconds to mix the medication evenly before each administration.
3. Press down on the child-resistant cap and twist it counterclockwise to open the bottle; do not discard the cap.
4. Before you open the tasimelteon bottle for the first time, remove the seal from bottle and insert the press-in bottle adapter into the bottle. Press on the bottle adapter until it is even with the top of the bottle; after the bottle adapter is in place, do not remove it. Then, replace the cap by turning clockwise and shake well again for 30 seconds.
5. Push the plunger of the oral dosing syringe completely down. Insert the oral dosing syringe into the opening of the press-in bottle adapter as far as it will go.
6. With the oral dosing syringe in the bottle adapter, carefully turn the bottle upside down. Pull the plunger back to withdraw the amount of suspension prescribed by the doctor. If you are not sure how to correctly measure the dose, ask your doctor or pharmacist. If you see more than a few air bubbles in the oral dosing syringe, fully push in the plunger so that the liquid flows back into the bottle until the air bubbles are mostly gone.
7. Leave the oral dosing syringe in the bottle adapter and turn the bottle upright. Carefully remove the oral dosing syringe from the bottle adapter. Replace the child-resistant cap securely.
8. Remove the dosing dispenser and slowly squirt the suspension directly into your mouth or your child's mouth and toward the inside of their cheek. Slowly push the plunger all the way in to give the entire dose. Make sure the child has time to swallow the medication.
9. Remove the plunger from the barrel of the oral dosing syringe. Rinse the oral dosing syringe barrel and plunger with water and when dry, put the plunger back into the oral dosing syringe. Do not wash the oral dosing syringe in the dishwasher.
10. Do not discard the oral dosing syringe. Always use the oral dosing syringe that comes with tasimelteon to measure your child's dose.
11. Refrigerate the suspension after each use.

You may become sleepy soon after you take tasimelteon. After you take tasimelteon, you should complete any necessary bedtime preparations and go to bed. Do not plan any other activities for this time.

Tasimelteon controls certain sleep disorders, but does not cure them. It may take several weeks or months before you feel the full benefit of tasimelteon. Continue to take tasimelteon even if you feel well. Do not stop taking tasimelteon without talking to your doctor.

Tasimelteon is not available in pharmacies. You can only get tasimelteon through the mail from a specialty pharmacy. Ask your doctor if you have any questions about receiving your medication.

Tasimelteon capsules and suspension may not be able to be substituted for one another. Ask your pharmacist if you have any questions about the type of tasimelteon product your doctor has prescribed.

Are there OTHER USES for this medication?

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

What SPECIAL PRECAUTIONS should I follow?

Before taking tasimelteon,

• tell your doctor and pharmacist if you are allergic to tasimelteon, any other medications, or any of the ingredients in tasimelteon capsules and suspension. Ask your pharmacist for a list of the ingredients.
• tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take while taking tasimelteon. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• tell your doctor if you have or have ever had liver disease.
• tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. If you become pregnant while taking tasimelteon, call your doctor.
• you should know that tasimelteon may make you drowsy. Do not drive a car or operate machinery until you know how this medication affects you.
• ask your doctor about the safe use of alcoholic beverages while you are taking tasimelteon. Alcohol can make the side effects from tasimelteon worse.
• tell your doctor if you use tobacco products. Cigarette smoking may decrease the effectiveness of this medication.

What SPECIAL DIETARY instructions should I follow?

Unless your doctor tells you otherwise, continue your normal diet.

What should I do IF I FORGET to take a dose?

Skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

What SIDE EFFECTS can this medicine cause?

Tasimelteon may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• headache
• nightmares or unusual dreams
• fever or painful, difficult, or frequent urination
• fever, cough, shortness of breath, or other signs of infection

Tasimelteon may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

What should I do in case of OVERDOSE?

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at http://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

What should I know about STORAGE and DISPOSAL of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from light, excess heat and moisture (not in the bathroom). Refrigerate the suspension. After opening the suspension bottle, discard any unused liquid medication after 5 weeks (for the 48 mL bottle) and after 8 weeks (for the 158 mL bottle).

Keep all medication out of sight and reach of children as many containers are not child-resistant. Always lock safety caps. Place the medication in a safe location - one that is up and away and out of their sight and reach. http://www.upandaway.org

Dispose of unneeded medications in a way so that pets, children, and other people cannot take them. Do not flush this medication down the toilet. Use a medicine take-back program. Talk to your pharmacist about take-back programs in your community. Visit the FDA's Safe Disposal of Medicines website http://goo.gl/c4Rm4p for more information.

What OTHER INFORMATION should I know?

Keep all appointments with your doctor.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

Keep a written list of all of the prescription and nonprescription (over-the-counter) medicines, vitamins, minerals, and dietary supplements you are taking. Bring this list with you each time you visit a doctor or if you are admitted to the hospital. You should carry the list with you in case of emergencies.

This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.

The American Society of Health-System Pharmacists, Inc. represents that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists, Inc. makes no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information is not a substitute for medical care.

AHFS^® Patient Medication Information™ Copyright, 2025. The American Society of Health-System Pharmacists^®, 4500 East-West Highway, Suite 900, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.

Selected Revisions: May 15, 2021.