What is mercaptopurine?
Mercaptopurine is a medicine used to kill cancer cells. It stops the cells from dividing and making new cells. You may need to disintegrate mercaptopurine tablets in warm water in an oral syringe if your child cannot swallow the tablets or portion of tablets. The steps are described in the section below.
How to disintegrate mercaptopurine tablets in an oral syringe
- Gather the following supplies:
- Gloves
- Mercaptopurine tablet: If you need to give your child a ¼ or ½ split tablet, please see Safe handling of hazardous medicines at home: Giving cut tablets for instructions for safely cutting tablets.
- A 12 mL or 20 mL oral syringe
- Syringe tip cap
- Cup of very warm tap water (it should be a comfortable temperature on the hands—nothing that can burn skin)
- Put on gloves to minimize your contact with the medication.
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Remove the plunger from the syringe.
- Place the tablet (or portion of the tablet) into the syringe. The tablet should lie flat.
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Insert the plunger back into the oral syringe and have it flush against the tablet.
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Withdraw about 5 mL of very warm tap water into the syringe. It does not have to be exact and can be a bit more. If using a 20 mL oral syringe, you can add a bit more water (1 mL to 2 mL) and extra air if you find it works better.
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Draw back the plunger to add about 5 mL to 6 mL of air. It does not have to be exact but needs to be at least 5 mL.
- Cap the syringe tip firmly with the syringe tip cap.
- Start shaking the syringe like you would a salad dressing bottle. Do not shake too vigorously or too gently. If you feel any hand strain, take a break or switch hands.
- You should hear constant pinging of the tablet as you are shaking the syringe as it hits the front of the syringe and then the back. It's like a ping-pong match.
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When you do not hear any more pinging sound, put the syringe on its side and let the sediment (very small pieces of the tablet) settle first (at least 30 seconds). Then, hold the syringe up to a bright light to see if any part of the tablet is left. It should fully disintegrate in five to seven minutes of constant shaking when using a whole or ½ tablet. For ¼ tablets, you can use 3 mL of water if 5 mL is too much.
The picture in this step shows a partial tablet. If your syringe looks like this, you will need to keep shaking.
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If any tablet portion, even if it is very small, is not yet fully disintegrated into small granules, shake for another minute and then recheck the syringe.
This is what you should see.
- Once it is fully disintegrated into small granules, shake the syringe well, remove the tip cap, and administer the medication immediately.
- If you need to administer a bit at a time, be sure to shake the syringe well between administrations to ensure all granules/sediment is suspended and then given.
- Once all the medication is administered, pull back the syringe plunger and inspect the inside of the top area of the syringe and the end of the plunger to ensure no sediment is stuck to it. If any sediment remains, draw up more warm water into the syringe and shake until the sediment is disintegrated into the water. Then, administer this liquid.
Frequently asked questions about disintegrating mercaptopurine tablets
Can I use a dissolve and dose (DAD) device to disintegrate the tablets?
No, it will not work as there is not enough air space available, and the tablet cannot hit the top of the DAD easily. It takes far too long to disintegrate and could be well over an hour.
Can I use room-temperature tap water?
You can, but the tablet will take a lot longer to disintegrate. It could take 10 to 30 minutes.
Can I use boiling water?
No, this is too hot and can burn skin when you are preparing the liquid. Only very hot tap water (comfortable for hand to touch) should be used.
Does it have to be exactly 5 mL of warm tap water?
No. It can be a little more or less (4.8 mL to 6 mL). If you have, for example, 4 mL, it will take longer for the tablet to disintegrate. Having more water is fine. Keep in mind that the entire amount needs to be taken.
I am using ¼ tablet for the dose. Do I have to use 5 mL of water?
You can use less water for the ¼ dose. It will disintegrate in 3 mL of water (or more). For ½ and whole tablets, the minimum is 5 mL of water.
Do I need the air in the syringe for disintegration?
It is critical to have air in the syringe as this allows the tablet to hit the front and back of the syringe when shaking. This is what stresses the tablet, allowing it to disintegrate in five to seven minutes.
If I see a very small piece of tablet left, do I need to keep shaking?
Yes, the tablet must be in small granules, as the procedure pictures show. Any portion, no matter how small, will then be squished up against the front of the syringe and plunger, creating a sticky paste. You will need to add in more warm tap water and shake for another five to eight minutes to get it to disintegrate in water. It is best to take the time needed to fully disintegrate the tablet so this does not happen.
Can I use a 20 mL oral syringe?
Yes, but it will take at least another two minutes of shaking to get the tablet to disintegrate. The 12 mL oral syringe works best.
Can I prepare this ahead of time?
Since it is given once a day, it is best to ensure you have enough time to prepare and administer the dose after prepared. If you need to put the syringe down for a few minutes and then come back to it, the tablet may become stuck to the inside of the syringe. Resume shaking. You need to see that the tablet has dislodged back into the water. Keep shaking until it is fully disintegrated.
I finished disintegrating the tablet in the syringe but need to put it down for 10 to 30 minutes before I give it. Is this OK?
Yes, if the tablet has been fully disintegrated and the syringe is laid down, then the tablet sediment will settle out as a yellow line on the side of the syringe. You should be able to resuspend it back in the water with shaking, which can take one to two minutes.