WHY is this medicine prescribed?
Doxecitine and doxribtimine is used to treat thymidine kinase 2 deficiency (TK2d; genetic disorder that causes progressive muscle weakness). Doxecitine and doxribtimine are both in a class of medications called pyrimidine nucleosides. They work by replacing the mitochondrial DNA absent in TK2d that leads to muscle weakness.
HOW should this medicine be used?
Doxecitine and doxribtimine comes as a powder to be mixed with water to take by mouth. Take with food three times a day. Each dose should be taken 6 hours apart, plus or minus 2 hours on either side. Take doxecitine and doxribtimine at around the same times every day.
Take doxecitine and doxribtimine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
You will be provided a ZX2000 administration kit to prepare and give the dose of doxecitine and doxribtimine. It is important to only use this to prepare and give the dose.
You will be told how many packets you will need to use to get your daily dose. Each packet requires 40 mL of room temperature water.
To mix doxecitine and doxribtimine:
To give a dose of doxectine and doxribtimine:
If giving through a feeding tube, follow the instructions of the feeding tube manufacturer on how to give the dose. Flush any remaining solution in the syringe or feeding tube until no solution is remaining.
Your doctor will probably start you on a low dose of doxecitine and doxribtimine and gradually increase your dose, not more than once every 2 weeks.
You will be given Patient Instructions for Use. Read the instructions carefully and ask your doctor or pharmacist any questions you may have.
Doxecitibe and doxribtimine controls TK2d but does not cure it. Do not stop taking doxecitibe and doxribtimine without talking to your doctor.
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 doxecitine and doxribtimine,
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?
Take the missed dose as soon as you remember it. However, if it is within 2 hours of the next 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?
Doxecitine and doxribtimine may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:
Some side effects can be serious. If you experience any of these symptoms, call your doctor immediately:
Doxecitine and doxribtimine 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 excess heat and moisture (not in the bathroom). The mixture of powder after water has been added can be stored at room temperature or in the refrigerator.
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 and the laboratory. Your doctor may order certain lab tests to check your body's response to doxecitine and doxribtimine.
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, 2026. 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: January 15, 2026.