Uses for azathioprine

Azathioprine is used to prevent rejection of a transplanted kidney. It belongs to the group of medicines known as immunosuppressive agents. Azathioprine will lower the body's natural immunity in patients who receive transplants to prevent rejection of the new kidney. It is also used to relieve joint pain and swelling for patients with active rheumatoid arthritis.

This medicine is available only with your doctor's prescription.

Before using azathioprine

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Appropriate studies have not been performed on the relationship of age to the effects of azathioprine in the pediatric population. Safety and efficacy have not been established.

Geriatric

No information is available on the relationship of age to the effects of azathioprine in geriatric patients.

Breast Feeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Interactions with Medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

• Febuxostat

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Adenovirus Vaccine Type 4, Live
• Adenovirus Vaccine Type 7, Live
• Alacepril
• Alfalfa
• Allopurinol
• Bacillus of Calmette and Guerin Vaccine, Live
• Benazepril
• Black Cohosh
• Captopril
• Cilazapril
• Dengue Tetravalent Vaccine, Live
• Doxorubicin
• Doxorubicin Hydrochloride Liposome
• Enalaprilat
• Enalapril Maleate
• Fosinopril
• Influenza Virus Vaccine, Live
• Lisinopril
• Measles Virus Vaccine, Live
• Mercaptopurine
• Moexipril
• Mumps Virus Vaccine, Live
• Mycophenolic Acid
• Olsalazine
• Oxypurinol
• Pentopril
• Perindopril
• Poliovirus Vaccine, Live
• Quinapril
• Ramipril
• Ribavirin
• Rotavirus Vaccine, Live
• Rubella Virus Vaccine, Live
• Ruxolitinib
• Smallpox Vaccine
• Spirapril
• Sulfamethoxazole
• Sulfasalazine
• Tofacitinib
• Trandolapril
• Trimethoprim
• Typhoid Vaccine, Live
• Varicella Virus Vaccine, Live
• Yellow Fever Vaccine
• Zofenopril
• Zoster Vaccine, Live

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Acenocoumarol
• Cyclosporine
• Phenprocoumon
• Warfarin

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

• Anemia or
• Blood or bone marrow problems or
• Leukopenia (low white blood cells) or
• Stomach or bowel problems (eg, nausea, vomiting, diarrhea) or
• Thrombocytopenia (low number of platelets)—Use with caution. May make these conditions worse.

• Crohn's disease or
• Ulcerative colitis—Use with caution. May increase risk for more side effects.

• Infection—May decrease your body's ability to fight infection.

• Kidney disease or
• Liver disease—Use with caution. The effects may be increased because of slower removal of the medicine from the body.

Proper use of azathioprine

Take this medicine exactly as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered. Taking too much may increase the chance of unwanted effects, and taking too little will not help your condition.

This medicine is sometimes given together with other medicines. If you are using several medicines together, make sure you understand how to take them during the day. Ask your doctor to help you plan a way to remember to take your medicines at the right times.

Do not stop using this medicine without first checking with your doctor.

Azathioprine sometimes causes nausea or vomiting. Taking this medicine after meals, in divided doses, or at bedtime may lessen stomach upset. Talk to your doctor if you have questions or continue to have problems with nausea or vomiting.

Dosing

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

• For oral dosage form (tablets):
  • For kidney transplant rejection:
    • Adults—Dose is based on body weight and must be determined by your doctor. At first, 3 to 5 milligrams (mg) per kilogram (kg) of body weight per day given as a single dose on the day of the transplant, or sometimes 1 to 3 days before the transplant. Your doctor may adjust your dose as needed.
    • Children—Use and dose must be determined by your doctor.
  • For rheumatoid arthritis:
    • Adults—Dose is based on body weight and must be determined by your doctor. At first, 1 milligram (mg) per kilogram (kg) of body weight per day given as a single dose once a day or divided into two doses. Your doctor may adjust your dose as needed and tolerated. However, the dose is usually not more than 2.5 mg per kg of body weight per day.
    • Children—Use and dose must be determined by your doctor.

Missed Dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Precautions while using azathioprine

It is very important that your doctor check your progress at regular visits for any problems that may be caused by this medicine. Blood and urine tests may be needed to check for unwanted effects.

Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. If you think you have become pregnant while using this medicine, tell your doctor right away.

Do not use this medicine if you are also taking mercaptopurine (Purinethol®). Using these medicines together could cause serious unwanted effects.

If you are using azathioprine for arthritis, make sure your doctor knows if you had received chlorambucil (Leukeran®), cyclophosphamide (Cytoxan®, Neosar®), or melphalan (Alkeran®) to treat your arthritis in the past. Using azathioprine after these medicines may increase your risk for unwanted effects. Talk to your doctor if you have questions about this.

This medicine may increase your risk of getting certain types of cancer, especially of the skin, lymph system (lymphoma), or blood (leukemia). Talk to your doctor if you have concerns about this risk.

Use sunscreen or sunblock lotions with a sun protection factor (SPF) of at least 15 on a regular basis when you are outdoors. Wear protective clothing and hats, and stay out of direct sunlight between the hours of 10 am and 3 pm Avoid sunlamps and tanning beds.

While you are being treated with azathioprine, and after you stop treatment with it, do not have any immunizations (vaccines) without your doctor's approval. Azathioprine may lower your body's resistance and the vaccine may not work as well or you might get the infection the vaccine is meant to prevent. In addition, you should not be around other persons living in your household who receive live virus vaccines because there is a chance they could pass the virus on to you. Some examples of live vaccines include measles, mumps, influenza (nasal flu vaccine), poliovirus (oral form), rotavirus, and rubella. Do not get close to them and do not stay in the same room with them for very long. If you have questions about this, talk to your doctor.

Azathioprine can temporarily lower the number of white blood cells in your blood, increasing the chance of getting an infection. It can also lower the number of platelets, which are necessary for proper blood clotting. If this occurs, there are certain precautions you can take, especially when your blood count is low, to reduce the risk of infection or bleeding:

• If you can, avoid people with infections. Check with your doctor as soon as possible if you think you are getting an infection or if you get a fever or chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.
• Check with your doctor as soon as possible if you notice any unusual bleeding or bruising, black, tarry stools, blood in the urine 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 your teeth and gums. Check with your doctor before having any dental work done.
• Do not touch your eyes or the inside of your nose unless you have just washed your hands and have not touched anything else.
• Be careful not to cut yourself when you are using sharp objects such as a safety razor or fingernail or toenail cutters.
• Avoid contact sports or other situations where bruising or injury could occur.

This medicine may increase your risk of developing infections, including a serious brain infection called progressive multifocal leukoencephalopathy. Avoid being near people who are sick or have infections while you are using this medicine. Wash your hands often. Tell your doctor if you have any kind of infection before you start using this medicine. Also tell your doctor if you have ever had an infection that would not go away or an infection that kept coming back.

Check with your doctor right away if you have more than one of these symptoms while you are using this medicine: severe nausea or vomiting, diarrhea, fever, rash, a general feeling of discomfort or illness, muscle or joint pain, lightheadedness or dizziness, or unusual tiredness or weakness. These could be symptoms of a serious reaction to the medicine in your bowel.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Side Effects of azathioprine

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

• Black, tarry stools
• bleeding gums
• blood in the urine or stools
• chest pain
• chills
• cough
• fever
• hoarseness
• lower back or side pain
• painful or difficult urination
• pinpoint red spots on the skin
• sore throat
• sores, ulcers, or white spots on the lips or in the mouth
• swollen glands
• unusual bleeding or bruising
• unusual tiredness or weakness

Less common

• Cloudy urine
• fever sores on the skin
• general feeling of illness
• greatly decreased frequency of urination or amount of urine
• skin rash
• swelling of the feet or lower legs
• weight loss
• yellow skin or eyes

Rare

• Bloating
• clay-colored stools
• constipation
• dark urine
• decreased appetite
• diarrhea (severe)
• fast heartbeat
• fever (sudden)
• headache
• indigestion
• itching
• loss of appetite
• muscle or joint pain
• nausea (severe)
• pains in the stomach, side, or abdomen, possibly radiating to the back
• redness or blisters on the skin
• stomach pain or tenderness
• swelling of the feet or lower legs
• unusual feeling of discomfort or illness (sudden)
• vomiting (severe)

Incidence not known

• Difficulty with breathing
• difficulty with moving
• fat in the stool
• general feeling of illness
• pale skin
• sores on the skin
• stomach cramps
• sudden loss of weight
• troubled breathing with movement
• weight loss

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

• Nausea (mild)
• swollen joints
• vomiting (mild)

Less common

• Hair loss or thinning of the hair

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

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