Doxecitine/doxribtimine (By mouth)

Doxecitine (dox-e-SYE-teen), Doxribtimine (dox-RIB-ti-meen)

Treats thymidine kinase 2 deficiency (TK2d).

Brand Name(s):

Kygevvi

When This Medicine Should Not Be Used:

How to Use This Medicine:

Liquid

• Take your medicine as directed. Your dose may need to be changed several times to find what works best for you.
• It is best to take this medicine with food or milk.
• To use:
  • When this medicine is prescribed for the first time, you will be provided with the carton of 30 packets and ZX2000 administration kit. Do not open the packets until you are ready to use them.
  • Prepare a one-day supply of this medicine each morning. Only use the dosing cup, mixing bottle, and oral syringe provided with your ZX2000 kit. Do not use the dosing cup, mixing bottle, and oral syringe if it appears dirty or damaged. Do not use a household measuring cup or spoon.
  • Wash your hands before and after using this medicine.
  • Pour the needed amount of room temperature water into the mixing bottle. Do not mix it with any other liquids or foods. Tap the packet on a hard surface to settle the powder to the bottom. Fold and tear or cut along the dotted line. Do not use spilled powder. Throw it away and use a new packet.
  • Empty the contents into the mixing bottle with water. Pour only 1 packet at a time until you have reached the prescribed number of packets for your one-day supply.
  • Screw the dosing cup tightly onto the mixing bottle. Place one hand at the end of the mixing bottle and the other hand at the end of dosing cup. Gently turn the mixing bottle upside down and back at least 20 times.
  • Check the mixture. If you see any powder, keep turning it upside down and back. The solution may be cloudy and have some remaining powder at the bottom or top.
  • Before you measure and take or give each dose, slowly turn the mixing bottle upside down and back at least 3 times. Unscrew the dosing cup and place it on a flat surface.
  • For doses 50 milliliters (mL) or more: Pour the solution into the dosing cup. Drink or give the entire solution from the cup.
  • For doses less than 50 mL: Pour the solution into the dosing cup. Use the oral syringe to draw the prescribed dose. Push the plunger all way down to make sure there is no air. Place the tip of the oral syringe into the dosing cup. Pull the plunger back until it reaches the prescribed dose. Make sure your child is sitting upright when giving this medicine. Place the tip of the syringe into your child's mouth and point the syringe towards the inside of either cheek. Push the plunger all the way down.
  • You may also give this medicine through a feeding tube. After giving the medicine, flush the tube with the amount of water recommended by the doctor until no solution is left.
  • Clean the mixing bottle, dosing cup, and seal with a clean towel. Put the dry seal back into the dosing cup, with the thin side of the seal facing the groove. Wash the oral syringe with cold water. Do not wash them in the dishwasher.
  • Do not save the solution for another day.
• Read and follow the patient instructions that come with this medicine. Talk to your doctor or pharmacist if you have any questions.
• Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose. If you miss a dose of this medicine and it is within 2 hours until your next scheduled dose, skip the missed dose and take your next dose at the normal time.
• If you spit out the dose or do not take the full dose of this medicine, do not take another dose. Take your next dose at the next scheduled time.
• Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. You may store mixed solution at room temperature or in the refrigerator. Throw away unused oral liquid 16 hours after preparing this medicine or after taking or giving the 3 doses, whichever comes first.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

Warnings While Using This Medicine:

• Tell your doctor if you are pregnant or breastfeeding, or if you have kidney disease or liver disease.
• This medicine may cause the following problems:
  • Liver problems
  • Stomach or bowel problems
• Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.
• Keep all medicine out of the reach of children. Never share your medicine with anyone.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

• Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
• Dark urine or pale stools, nausea, vomiting, loss of appetite, stomach pain, yellow skin or eyes
• Diarrhea

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 1/4/2026