What is Didanosine?

Commonly Used Brand Name(s)Videx, Videx EC, Videx Pediatric

Therapeutic ClassificationsAntiretroviral Agent

Pharmacologic ClassificationsNucleoside Reverse Transcriptase Inhibitor

Blackbox WarningTOP

Oral route (Capsule, Delayed Release;Powder for Solution)

Fatal and nonfatal pancreatitis has occurred during therapy with didanosine. Didanosine should be suspended in patients with suspected pancreatitis and discontinued in patients with confirmed pancreatitis. Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported. Fatal lactic acidosis has been reported in pregnant women who received the combination of didanosine and stavudine with other antiretroviral agents. The combination of didanosine and stavudine should be used with caution during pregnancy and is recommended only if the potential benefit clearly outweighs the potential risk .

OverviewTOP

Didanosine is used in combination with other medicines for the treatment of human immunodeficiency virus (HIV) infection. HIV is the virus that causes acquired immune deficiency syndrome (AIDS).

Didanosine will not cure or prevent HIV infection or AIDS. 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.

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

The buffered tablets that are to be chewed, crushed or mixed with water are no longer available in the United States. This product was voluntarily discontinued, and it was not due to safety concerns. Didanosine delayed-release capsules (Videx® EC) and pediatric powder for oral solution are still available.

Proper UseTOP

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 first with your doctor.

This medicine comes with a Medication Guide. Read and follow the instructions in the insert carefully. Ask your doctor if you have any questions.

Keep taking didanosine for the full time of treatment, even if you begin to feel better. Only take medicine that your doctor has prescribed specifically for you. Do not share your medicine with other people.

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 doctor.

Didanosine should be taken on an empty stomach since food may keep it from working properly. Didanosine oral liquid should be taken at least 30 minutes before or 2 hours after you eat.

Swallow the delayed-release capsule whole. Do not break, crush, chew, or open it.

Shake the oral liquid before use. Measure each dose with a specially marked measuring spoon or measuring cup. The average household teaspoon may not hold the right amount of liquid.

DosingTOP

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 HIV infection:
- For oral dosage form (delayed-release capsules):
  - Adults, teenagers, and children who can swallow capsules—Dose is based on body weight and must be determined by your doctor.
    - For patients weighing 60 kilograms (kg) or more—400 milligrams (mg) once a day.
    - For patients weighing 25 kg to less than 60 kg—250 mg once a day.
    - For patients weighing 20 kg to less than 25 kg—200 mg once a day.
  - Children weighing less than 20 kg—The oral capsules are not given to small children.
- For oral dosage form (solution):
  - Adults weighing 60 kilograms (kg)—Dose is based on body weight and must be determined by your doctor. The usual dose is 200 milligrams (mg) two times a day or 400 mg once a day.
  - Adults weighing less than 60 kg—Dose is based on body weight and must be determined by your doctor. The usual dose is 125 mg two times a day or 250 mg once a day.
  - Teenagers, children, and infants 8 months of age and older—Dose is based on body size and must be determined by your doctor. The usual dose is 120 milligrams per square meter (mg/m(2)) two times a day.
  - Infants 2 weeks to 8 months old—Dose is based on body size and must be determined by your doctor. The usual dose is 100 mg/m(2) two times a day.
  - Infants younger than 2 weeks old—Use and dose must be determined by your doctor.

Missed DoseTOP

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.

Use & StorageTOP

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.

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

Store the oral liquid in the refrigerator. Throw away any unused medicine after 30 days.

Before UsingTOP

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:

AllergiesTOP

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.

PediatricTOP

Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of didanosine in children 2 weeks of age and older.

GeriatricTOP

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of didanosine in the elderly. However, elderly patients are more likely to have age-related kidney problems, which may require caution and an adjustment in the dose for patients receiving didanosine.

PregnancyTOP

	Pregnancy Category	Explanation
All Trimesters	B	Animal studies have revealed no evidence of harm to the fetus, however, there are no adequate studies in pregnant women OR animal studies have shown an adverse effect, but adequate studies in pregnant women have failed to demonstrate a risk to the fetus.

Breast FeedingTOP

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.

Drug InteractionsTOP

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.

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.

Darunavir
Hydroxyurea
Orlistat
Stavudine
Tenofovir Disoproxil Fumarate
Zalcitabine

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.

Atazanavir
Atevirdine
Ciprofloxacin
Delavirdine
Enoxacin
Ganciclovir
Indinavir
Itraconazole
Ketoconazole
Lomefloxacin
Methadone
Metoclopramide
Moxifloxacin
Nelfinavir
Norfloxacin
Ofloxacin
Ranitidine
Rifabutin
Ritonavir
Sulfamethoxazole
Trimethoprim
Trovafloxacin Mesylate
Valganciclovir

Other InteractionsTOP

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. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

PrecautionsTOP

It is very important that your doctor check your or your child's progress at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects.

Do not use didanosine if you or your child are also using allopurinol (Zyloprim®) or ribavirin (Copegus®, Rebetol®). Using these medicines together may cause serious side effects.

This medicine may cause a life-threatening condition called pancreatitis. Check with your doctor right away if you or your child have more than one of these symptoms: bloating, chills, constipation, darkened urine, a fast heartbeat, fever, indigestion, loss of appetite, nausea, pains in the stomach, side, or abdomen, possibly radiating to the back, vomiting, or yellow eyes or skin.

Two rare but serious reactions to this medicine are lactic acidosis (too much acid in the blood) and liver toxicity, which includes an enlarged liver. These are more common if you are female, very overweight (obese), or have been taking anti-HIV medicines for a long time. Call your doctor right away if you or your child have more than one of these symptoms: abdominal or stomach discomfort or cramping, dark urine, decreased appetite, diarrhea, a general feeling of discomfort, light-colored stools, muscle cramping or pain, nausea, unusual tiredness or weakness, trouble breathing, vomiting, or yellow eyes or skin.

Check with your doctor right away if you or your child have abdominal or stomach pain, black, tarry stools, bleeding gums, blood in the urine or stools, pinpoint red spots on the skin, or unusual bleeding or bruising. These may be symptoms of a condition called non-cirrhotic portal hypertension.

Tell your doctor right away if you or your child start having numbness, tingling, or burning pain in your hands, arms, legs, or feet. These may be symptoms of a condition called peripheral neuropathy.

Your immune system may get stronger when you start taking HIV medicines. Sometimes the immune system will start to fight infections that were hidden in your body, such as pneumonia or tuberculosis. Tell your doctor right away if you notice any changes in your health.

This medicine may cause you or your child to have excess body fat. Tell your doctor right away if you notice changes in your body shape, including an increased amount of body fat in the neck or upper back, face, around the chest, or stomach area. You might also lose fat from your legs, arms, or face.

Check with your doctor right away if you or your child start to see unusual colors or have blurred vision. Your doctor may want you to have your eyes checked regularly by an eye doctor (ophthalmologist).

Do not drink alcohol while you are using this medicine.

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 doctor.

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.