In the U.S.—

• Antineoplastic

Tretinoin (TRET-i-noyn) belongs to the group of medicines known as retinoids (RET-i-noyds). It is used to treat a form of leukemia (acute promyelocytic leukemia [APL]).

Tretinoin has side effects that can be very serious. Be sure that you discuss with your doctor the good that this medicine can do as well as the risks of taking it.

This medicine is available only with your doctor's prescription, in the following dosage form(s):

Oral
• Capsules (U.S.)

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 tretinoin, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to tretinoin or to acitretin, etretinate, isotretinoin, or vitamin A preparations. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Tretinoin must not be taken during pregnancy because there is a very high risk of causing severe birth defects in the infant. In addition, tretinoin must not be taken if there is a chance that you may become pregnant during treatment or within 1 month after treatment is ended. Women who are able to have children, and even some women who have started the menopause, must have a pregnancy test done within 1 week before starting tretinoin, to make sure they are not pregnant. The pregnancy test must be repeated once a month during treatment. During treatment with tretinoin, and for a month after treatment is over, you must use two effective forms of birth control at the same time. If you have any questions about what kinds of birth control to use, check with your health care professional. Be sure that you have discussed this information with your doctor. You will be asked to sign an informed consent form stating that you have received and understand the above information.

Breast-feeding—It is not known whether tretinoin passes into the breast milk. However, because this medicine can cause serious side effects, women should stop breast-feeding before starting treatment.

Children—Studies in a limited number of children between 1 and 16 years of age have shown that children may be especially sensitive to the effects of this medicine, and may be more likely than adults to experience severe headaches and some other side effects during treatment.

Older adults—Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing use of tretinoin in the elderly with use in other age groups.

Other 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 tretinoin, it is especially important that your health care professional know if you are taking any of the following:

• Corticosteroids (cortisone-like medicine) or
• Cimetidine (e.g., Tagamet) or
• Cyclosporine (e.g., Sandimmune) or
• Diltiazem (e.g., Cardizem) or
• Erythromycin (e.g., E-Mycin, Ilotycin) or
• Ketoconazole (e.g., Nizoral) or
• Pentobarbital (e.g., Nembutal) or
• Phenobarbital (e.g., Luminal) or
• Rifampin (e.g., Rifadin) or
• Verapamil (e.g., Calan)—These medicines may increase or decrease the metabolism (breakdown) of tretinoin, leading to higher-than-usual or lower-than-usual amounts of tretinoin in the body

It is very important that you take tretinoin only 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. To do so may increase the chance of side effects.

Dosing—

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

• For oral dosage form (capsules):
  • For acute promyelocytic leukemia (APL):
    • Adults—Dose is based on body size and must be determined by your doctor. The usual dose is 45 milligrams (mg) for each square meter of body surface area a day, given in two equally divided doses.
    • Children—The dose will 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, check with your health care professional to find out how much medicine to take for the next dose.

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 other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

Your doctor should check your progress at regular visits to make sure that the medicine is working properly and to check for unwanted effects.

Tretinoin causes fever, headache, tiredness, and weakness in most people who take it. It is very important that you continue taking the medicine even if it makes you feel ill. Your health care professional may be able to suggest ways to relieve some of these effects. However, if you develop a very severe headache or a headache that occurs together with nausea, vomiting, or vision problems, check with your doctor right away.

Tretinoin sometimes causes a severe reaction that affects the lungs at first, but can later spread to other parts of the body. Signs of this reaction include breathing problems, bone pain, chest pain, and fever. Check with your doctor right away if any of these effects occur during treatment .

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
  • Bone pain;  discomfort or pain in chest ;  fever;  shortness of breath, troubled breathing, tightness in chest, or wheezing;  weight gain (occurring together with any of the other symptoms listed before)  
  
  

• Less common
  • Convulsions (seizures);  difficulty in speaking, slow speech, or inability to speak;  feeling of heaviness in chest;  headache (severe);  inability to move arms, legs, or muscles of the face;  nausea and vomiting (occurring together with a headache);  pain in back or left arm;  vision problems (occurring together with a headache) 
  
  

Also, check with your doctor as soon as possible if any of the following side effects occur:

• More common
  • Any change in vision (not occurring with a headache);  coughing, sneezing, sore throat, and stuffy or runny nose;  cracked lips;  crusting, redness, pain, or sores in mouth or nose;  decreased urination;  earache or feeling of fullness in the ear;  increase or decrease in blood pressure;  irregular heartbeat;  mental depression;  pain and swelling in leg or foot;  skin rash;  swelling of abdomen (stomach area);  swelling of face, fingers, hands, feet, or lower legs 
  
  

• Less common
  • Cramping or pain in stomach (severe);  difficult or painful urination;  drowsiness (very severe and continuing);  hallucinations (seeing, hearing, or feeling things that are not there);  hearing loss ;  heartburn, indigestion, or nausea (severe and continuing) ;  mood, mental, or personality changes;  pain in lower back or side;  swollen area that feels sore and tender;  yellow eyes or skin  
  
  

Other 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. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • Anxiety;  burning, crawling, or tingling feeling in the skin;  confusion;  constipation;  diarrhea;  dizziness;  dryness of skin, mouth, or nose;  flushing;  general feeling of discomfort or illness;  hair loss;  headache (mild and not occurring together with other side effects);  indigestion;  itching of skin;  loss of appetite;  muscle pain;  nausea and vomiting (not occurring together with a headache) ;  shivering;  trouble sleeping ;  weight loss 
  
  

• Less common
  • Anxiety and restlessness (occurring together);  clumsiness or unsteadiness when walking;  forgetfulness ;  frequent urination;  trembling, sometimes with a flapping movement;  weakness in legs  
  
  

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