THIOGUANINE (Systemic)
Some commonly used brand names are:
In the U.S.?
In Canada?
Generic name product may be available in the U.S.
Category
Description
Thioguanine (thye-oh-GWON-een) belongs to the group of medicines knownas antimetabolites. It is used to treat some kinds of cancer.
Thioguanine interferes with the growth of cancer cells, which are eventuallydestroyed. Since the growth of normal body cells may also be affected by thioguanine,other effects will also occur. Some of these may be serious and must be reportedto your doctor. Other effects may not be serious but may cause concern. Someeffects may not occur for months or years after the medicine is used.
Before you begin treatment with thioguanine, you and your doctor shouldtalk about the good this medicine will do as well as the risks of using it.
Thioguanine is available only with your doctor's prescription, in the followingdosage form:
Oral- Tablets (U.S. and Canada)
Before Using This Medicine
In deciding to use a medicine,the risks of taking the medicine must be weighed against the good it willdo. This is a decision you and your doctor will make. For thioguanine, thefollowing should be considered:
Allergies?Tell your doctor if you have ever had any unusual orallergic reaction to thioguanine.
Pregnancy?Tell your doctor if you are pregnant or if you intendto have children. There is a chance that this medicine may cause birth defectsif either the male or female is taking it at the time of conception or ifit is taken during pregnancy. In addition, many cancer medicines may causesterility which could be permanent. Although this has not been reported withthis medicine, the possibility should be kept in mind.
Be sure that you have discussed this with your doctor before taking thismedicine. It is best to use some kind of birth control while you are takingthioguanine. Tell your doctor right away if you think you have become pregnantwhile taking thioguanine.
Breast-feeding?Tell your doctor if you are breast-feeding or ifyou intend to breast-feed during treatment with this medicine. Because thioguaninemay cause serious side effects, breast-feeding is generally not recommendedwhile you are receiving it.
Children?Children are especially sensitive to the effectsof thioguanine. This may increase the chance of liver toxicity during treatment.
Older adults?Many medicines have not been tested in older people.Therefore, it may not be known whether they work exactly the same way theydo in younger adults or if they cause different side effects or problems inolder people. There is no specific information about the use of thioguaninein the elderly.
Other medicines?Although certain medicines should not be usedtogether at all, in other cases two different medicines may be used togethereven if an interaction might occur. In these cases, your doctor may want tochange the dose, or other precautions may be necessary. When you are takingthioguanine, it is especially important that your health care professionalknow if you are taking any of the following:
- Antithyroid agents (medicine for overactive thyroid) or
- Azathioprine (e.g., Imuran) or
- Chloramphenicol (e.g., Chloromycetin) or
- Colchicine or
- Flucytosine (e.g., Ancobon) or
- Interferon (e.g., Intron A, Roferon-A) or
- Plicamycin (e.g., Mithracin) or
- Zidovudine (e.g., Retrovir) or
- If you have ever been treated with x-rays or cancer medicines?Thioguaninemay increase the effects of these medicines or radiation therapy on the blood
- Mesalamine (e.g., Pentasa) or
- Olsalazine (e.g., Dipentum) or
- Sulfasalazine (e.g., Azulfidine)?May increase the effects ofthioguanine on the blood
- Probenecid (e.g., Benemid) or
- Sulfinpyrazone (e.g., Anturane)?Thioguanine may increase theconcentration of uric acid in the blood, which these medicines are used tolower
Other medical problems?The presence of other medicalproblems may affect the use of thioguanine. Make sure you tell your doctorif you have any other medical problems, especially:
- Chickenpox (including recent exposure) or
- Herpes zoster (shingles)?Risk of severe disease affecting otherparts of the body
- Gout (history of) or
- Kidney stones (history of)?Thioguanine may increase levelsof uric acid in the body, which can cause gout or kidney stones
- Infection?Thioguanine can reduce immunity to infection
- Kidney disease or
- Liver disease?Effects may be increased because of slower removalof thioguanine from the body
- Thiopurine methyltransferase deficiency (TPMT)?You may be moresensitive to the side effects of thioguanine, and your doctor may reduce yourdose
- Tumors?Thioguanine should not be used if your tumor did notget smaller when previously treated with thioguanine
Proper Use of This Medicine
Take this medicine only as directed by your doctor. Do not take moreor less of it, and do not take it more often than your doctor ordered. Theexact amount of medicine you need has been carefully worked out. Taking toomuch may increase the chance of side effects, while taking too little maynot improve your condition.
Thioguanine is sometimes given together with certain other medicines. Ifyou are using a combination of medicines, make sure that you take each oneat the right time and do not mix them. Ask your health care professional tohelp you plan a way to take your medicine at the right times.
While you are using thioguanine, your doctor may want you to drink extrafluids so that you will pass more urine. This will help prevent kidney problemsand keep your kidneys working well.
Thioguanine sometimes causes nausea and vomiting. However, it is very importantthat you continue to take this medicine, even if you begin to feel ill. Do not stop taking this medicine without first checking withyour doctor. Ask your health care professional for ways to lessen theseeffects.
If you vomit shortly after taking a dose of thioguanine, check with yourdoctor. You will be told whether to take the dose again or to wait until thenext scheduled dose.
Dosing?The dose of thioguanine will be different fordifferent patients. The dose that is used may depend on a number of things,including what the medicine is being used for, the patient's weight, and whetheror not other medicines are also being taken. If you aretaking thioguanine at home, follow your doctor's orders or the directionson the label. If you have any questions about the proper dose of thioguanine,ask your doctor.
Missed dose?If you miss a dose of this medicine, do not takethe missed dose at all and do not double the next one. Instead, go back toyour regular dosing schedule and check with your doctor.
Storage?To store this medicine:
- Keep out of the reach of children.
- Store away from heat and direct light.
- Do not store in the bathroom, near the kitchen sink, or in otherdamp places. Heat or moisture may cause the medicine to break down.
- Do not keep outdated medicine or medicine no longer needed. Be surethat any discarded medicine is out of the reach of children.
Precautions While Using This Medicine
It is very important that your doctor check your progress atregular visits to make sure that this medicine is working properlyand to check for unwanted effects.
While you are being treated with thioguanine, and after you stop treatmentwith it, do not have any immunizations (vaccinations)without your doctor's approval. Thioguanine may lower your body's resistanceand there is a chance you might get the infection the immunization is meantto prevent. Other people living in your household should not take or shouldnot have recently taken oral polio vaccine since there is a chance they couldpass the polio virus on to you. Also, avoid other persons who have taken oralpolio vaccine. Do not get close to them and do not stay in the same room withthem for very long. If you cannot take these precautions, you should considerwearing a protective face mask that covers the nose and mouth.
Thioguanine can lower the number of white blood cells in your blood temporarily,increasing the chance of getting an infection. It can also lower the numberof platelets, which are necessary for proper blood clotting. If this occurs,there are certain precautions you can take, especially when your blood countis low, to reduce the risk of infection or bleeding:
- If you can, avoid people with infections. Checkwith your doctor immediately if you think you are getting an infectionor if you get a fever or chills, cough or hoarseness, lower back or side pain,or painful or difficult urination.
- Check with your doctor immediately ifyou notice any unusual bleeding or bruising; black, tarry stools; blood inurine or stools; or pinpoint red spots on your skin.
- Be careful when using a regular toothbrush, dental floss, or toothpick.Your medical doctor, dentist, or nurse may recommend other ways to clean yourteeth and gums. Check with your medical doctor before having any dental workdone.
- Do not touch your eyes or the inside of your nose unless you havejust washed your hands and have not touched anything else in the meantime.
- Be careful not to cut yourself when you are using sharp objects suchas a safety razor or fingernail or toenail cutters.
- Avoid contact sports or other situations where bruising or injurycould occur.
Side Effects of This Medicine
Along with their needed effects,medicines like thioguanine can sometimes cause unwanted effects such as bloodproblems and other side effects. These and others are described below. Also,because of the way these medicines act on the body, there is a chance thatthey might cause other unwanted effects that may not occur until months oryears after the medicine is used. These delayed effects may include certaintypes of cancer, such as leukemia. Discuss these possible effects with yourdoctor.
Although not all of these side effects mayoccur, if they do occur they may need medical attention.
Other sideeffects may occur that usually do not need medical attention. These side effectsmay go away during treatment as your body adjusts to the medicine. Also, yourhealth care professional may be able to tell you about ways to prevent orreduce some of these side effects. Check with your health care professionalif any of the following side effects continue or are bothersome or if youhave any questions about them:
After you stop taking thioguanine, it may still produce some side effectsthat need attention. During this period of time, check with your doctor ifyou notice any of the following side effects:
Black, tarry stools; blood in urineor stools; cough or hoarseness; fever or chills; lower back or side pain; painful or difficult urination; pinpointred spots on skin; unusual bleeding or bruising
Other side effects not listed above may also occur insome patients. If you notice any other effects, check with your doctor.
Revised: 02/10/2005
