In the U.S.—

In Canada—

Another commonly used name is ddI.

• Antiviral, systemic

Didanosine (di-DAN-oe-seen) (also known as ddI) is used in the treatment of the infection caused by the human immunodeficiency virus (HIV). HIV is the virus responsible for acquired immune deficiency syndrome (AIDS).

Didanosine (ddI) will not cure or prevent HIV infection or AIDS; however, it helps keep HIV from reproducing and appears to slow down the destruction of the immune system. This may help delay the development of problems usually related to AIDS or HIV disease. Didanosine will not keep you from spreading HIV to other people. People who receive this medicine may continue to have the problems usually related to AIDS or HIV disease.

Didanosine may cause some serious side effects, including pancreatitis (inflammation of the pancreas). Symptoms of pancreatitis include stomach pain, and nausea and vomiting. Didanosine may also cause peripheral neuropathy. Symptoms of peripheral neuropathy include tingling, burning, numbness, and pain in the hands or feet. Check with your doctor if any new health problems or symptoms occur while you are taking didanosine .

Didanosine is available only with your doctor's prescription, in the following dosage forms:

Oral
• Capsules, delayed-release (U.S.)
• Oral solution, buffered powder (U.S.)
• Oral suspension, pediatric powder (U.S. and Canada)
• Tablets, buffered — chewable and for oral suspension (U.S. and Canada)

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 didanosine, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to didanosine. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Diet—Make certain your health care professional knows if you are on any special diet, such as a low-sodium (low-salt) diet. Didanosine chewable tablets and the oral solution packets contain a large amount of sodium. Also, didanosine tablets contain phenylalanine, which must be restricted in patients with phenylketonuria.

Pregnancy—Didanosine crosses the placenta. Studies in pregnant women have not been done. However, didanosine has not been shown to cause birth defects or other problems in animal studies. Also, it is not known whether didanosine reduces the chances that a baby born to an HIV-infected mother will also be infected. Before taking this medicine, make sure your doctor knows if you are pregnant or if you may become pregnant. This is especially important when taking didanosine together with stavudine.

Breast-feeding—It is not known whether didanosine passes into human breast milk. However, if your baby does not already have the AIDS virus, there is a chance that you could pass it to your baby by breast-feeding. Talk to your doctor first if you are thinking about breast-feeding your baby.

Children—Didanosine can cause serious side effects in any patient. Therefore, it is especially important that you discuss with your child's doctor the good that this medicine may do as well as the risks of using it. Your child must be carefully followed, and frequently seen, by the doctor while taking didanosine.

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 didanosine in the elderly with use in other age groups.

Other medicines—Although certain medicines should not be used together at all, in other cases 2 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 didanosine, it is especially important that your health care professional know if you are taking any of the following:

• Alcohol or
• Asparaginase (e.g., Elspar) or
• Azathioprine (e.g., Imuran) or
• Estrogens (female hormones) or
• Furosemide (e.g., Lasix) or
• Methyldopa (e.g., Aldomet) or
• Pentamidine (e.g., Pentam, Pentacarinat) or
• Sulfonamides (e.g., Bactrim, Septra) or
• Sulindac (e.g., Clinoril) or
• Thiazide diuretics (e.g., Diuril, Hydrodiuril) or
• Valproic acid (e.g., Depakote)—Use of these medicines with didanosine may increase the chance of pancreatitis (inflammation of the pancreas)

• Allopurinol (e.g., Lopurin, Purinol)—This medicine should not be used with didanosine; use of this medicine will increase the amount of didanosine in your body to abnormally high levels

• Chloramphenicol (e.g., Chloromycetin) or
• Cisplatin (e.g., Platinol) or
• Ethambutol (e.g., Myambutol) or
• Ethionamide (e.g., Trecator-SC) or
• Hydralazine (e.g., Apresoline) or
• Isoniazid (e.g., Nydrazid) or
• Lithium (e.g., Eskalith, Lithobid) or
• Metronidazole (e.g., Flagyl) or
• Nitrous oxide or
• Phenytoin (e.g., Dilantin) or
• Stavudine (e.g., D4T) or
• Vincristine (e.g., Oncovin) or
• Zalcitabine (e.g., HIVID)—Use of these medicines with didanosine may increase the chance of peripheral neuropathy (tingling, burning, numbness, or pain in your hands or feet)

• Ciprofloxacin (e.g., Cipro) or
• Enoxacin (e.g., Penetrex) or
• Itraconazole (e.g., Sporanox) or
• Ketoconazole (e.g., Nizoral) or
• Lomefloxacin (e.g., Maxaquin) or
• Norfloxacin (e.g., Noroxin) or
• Ofloxacin (e.g., Floxin)—Use of these medicines with didanosine may keep these medicines from working properly; these medicines should be taken at least 2 hours before or 2 hours after taking didanosine

• Dapsone (e.g., Avlosulfon)—Use of dapsone with didanosine may increase the chance of peripheral neuropathy (tingling, burning, numbness, or pain in your hands or feet); it may also keep dapsone from working properly; dapsone should be taken at least 2 hours before or 2 hours after taking didanosine

• Ganciclovir (e.g., Cytovene)—Use of these medicines with didanosine may keep these medicines from working properly; these medicines should be taken at least 2 hours after taking didanosine

• Nitrofurantoin (e.g., Macrodantin)—Use of nitrofurantoin with didanosine may increase the chance of pancreatitis (inflammation of the pancreas) and peripheral neuropathy (tingling, burning, numbness, or pain in your hands or feet)

• Delavirdine (e.g., Rescriptor) or
• Indinavir (e.g., Crixivan)—Use of these medicines with didanosine may keep these medicines from working properly; these medicines should be taken at least 1 hour before taking didanosine

• Tetracyclines (e.g., Achromycin, Minocin)—Use of tetracyclines with didanosine may increase the chance of pancreatitis (inflammation of the pancreas); it may also keep the tetracycline from working properly; tetracyclines should be taken at least 2 hours before or 2 hours after taking didanosine

• Alcoholism, active, or
• Increased blood triglycerides (substance formed in the body from fats in foods) or
• Pancreatitis (or a history of)—Patients with these medical problems may be at increased risk of pancreatitis (inflammation of the pancreas)

• Edema or
• Heart disease or
• High blood pressure or
• Kidney disease or
• Liver disease or
• Toxemia of pregnancy—The salt contained in the didanosine tablets and the oral solution packets may make these conditions worse

• Gouty arthritis—Didanosine may cause an attack or worsen gout

• Peripheral neuropathy—Didanosine may make this condition worse

• Phenylketonuria (PKU)—Didanosine tablets contain phenylalanine, which must be restricted in patients with PKU

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. Also, do not stop taking this medicine without checking with your doctor first. However, stop taking didanosine and call your doctor right away if you get severe nausea, vomiting, and stomach pain.

Otherwise, keep taking didanosine for the full time of treatment, even if you begin to feel better.

For patients taking didanosine delayed-release capsules :

• Capsules should be swallowed intact.

For patients taking didanosine for oral solution, buffered powder:

• Open the foil packet and pour its contents into approximately 1/2 glass (4 ounces) of water. Do not mix with fruit juice or other acid-containing drinks.
• Stir for approximately 2 to 3 minutes until the powder is dissolved.
• Drink at once.

For patients taking didanosine for oral suspension, pediatric powder:

• Use a specially marked measuring spoon or other device to measure each dose accurately. The average household teaspoon may not hold the right amount of liquid.

For patients taking didanosine tablets, buffered — chewable and for oral suspension:

• Tablets should be thoroughly chewed or crushed or mixed in at least 1 ounce of water before swallowing. The tablets are hard and some people may find them difficult to chew. If the tablets are mixed in water, stir well until a uniform suspension is formed and take at once. For additional flavoring, mix the prepared suspension with 1 ounce of clear apple juice.
• Two tablets must be taken together by patients over 1 year of age. These tablets contain a special buffer to keep didanosine from being destroyed in the stomach. In order to get the correct amount of buffer, 2 tablets always need to be taken together. Infants from 6 to 12 months of age will get enough buffer from just 1 tablet. For 1-tablet dose, a ½ ounce of clear apple juice may be added as a flavor enhancer.

Didanosine should be taken on an empty stomach since food may decrease the absorption in the stomach and keep it from working properly. Didanosine should be taken at least 2 hours before or 2 hours after you eat.

This medicine works best when there is a constant amount in the blood. To help keep the amount constant, do not miss any doses. If you need help in planning the best times to take your medicine, check with your health care professional.

Dosing—

The dose of didanosine 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 didanosine. If your dose is different, do not change it unless your doctor tells you to do so.

The number of capsules, tablets or teaspoonfuls of solution or suspension that you take depends on the strength of the medicine.

• For the treatment of advanced HIV infection or AIDS:
  • For oral dosage form (capsules, delayed-release):
    • Adults and teenagers—Dose is based on body weight.
      • For patients weighing less than 60 kilograms (kg) (132 pounds): 250 milligrams (mg) once daily.
      • For patients weighing 60 kg (132 pounds) or more: 400 mg once daily.
    • Children—The oral capsules are usually not used for small children.
  • For oral dosage form (solution, buffered powder):
    • Adults and teenagers—Dose is based on body weight.
      • For patients weighing less than 60 kilograms (kg) (132 pounds): 167 mg every twelve hours.
      • For patients weighing 60 kg (132 pounds) or more: 250 mg every twelve hours.
    • Children—The oral solution is usually not used for small children.
  • For oral dosage form (suspension, pediatric powder):
    • Adults and teenagers—The pediatric oral suspension is usually not used in adults and teenagers.
    • Children—Dose is based on body size and must be determined by your doctor.
  • For oral dosage form (tablets):
    • Adults and teenagers—Dose is based on body weight.
      • For patients weighing less than 60 kg (132 pounds): 125 mg every twelve hours, or 250 mg once daily.
      • For patients weighing 60 kg (132 pounds) or more: 200 mg every twelve hours, or 400 mg once daily.
    • Children—Dose is based on body size and must be determined by your doctor.

Missed dose—

If you do 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.

Only take medicine that your doctor has prescribed specifically for you. Do not share your medicine with others.

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.

It is very important that your doctor check your progress at regular visits.

Do not take any other medicines without checking with your doctor first. To do so may increase the chance of side effects from didanosine.

HIV may be acquired from or spread to other people through infected body fluids, including blood, vaginal fluid, or semen. If you are infected, it is best to avoid any sexual activity involving an exchange of body fluids with other people. If you do have sex, always wear (or have your partner wear) a condom (“rubber”). Only use condoms made of latex, and use them every time you have vaginal, anal, or oral sex. The use of a spermicide (such as nonoxynol-9) may also help prevent transmission of HIV if it is not irritating to the vagina, rectum, or mouth. Spermicides have been shown to kill HIV in lab tests. Do not use oil-based jelly, cold cream, baby oil, or shortening as a lubricant—these products can cause the condom to break. Lubricants without oil, such as K-Y jelly, are recommended. Women may wish to carry their own condoms. Birth control pills and diaphragms will help protect against pregnancy, but they will not prevent someone from giving or getting the AIDS virus. If you inject drugs , get help to stop. Do not share needles or equipment with anyone. In some cities, more than half of the drug users are infected and sharing even 1 needle or syringe can spread the virus. If you have any questions about this, check with your health care professional.

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:

• Less common
  • Nausea and vomiting;  stomach pain;  tingling, burning, numbness, and pain in the hands or feet 
  
  

• Rare
  • Convulsions (seizures);  fever and chills ;  shortness of breath;  skin rash and itching;  sore throat;  swelling of feet or lower legs;  unusual bleeding and bruising;  unusual tiredness and weakness ;  yellow skin and eyes 
  
  

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;  diarrhea;  difficulty in sleeping;  dryness of mouth;  headache;  irritability;  restlessness 
  
  

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