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• Do not keep outdated medicine or medicine no longer needed.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.

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