Didanosine

Didanosine is a prescription medication used to treat human immunodeficiency virus (HIV) infection. Didanosine belongs to a class of drugs called nucleoside analogues which work by decreasing the amount of HIV in the blood.

This medication comes in extended-release capsules (Videx EC) and a liquid form to be taken by mouth on an empty stomach. The capsules are usually taken once daily. The liquid is usually taken once or twice daily.

Common side effects of didanosine include diarrhea, stomach pain, nausea, and vomiting.

Didanosine is a prescription medicine used with other antiretroviral medicines to treat human immunodeficiency virus (HIV) infection in children and adults. 

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Didanosine may be found in some form under the following brand names:

• Videx

• Videx EC

The most common side effects of didanosine include:

• diarrhea
• stomach pain
• nausea
• vomiting
• headache
• rash

This is not a complete list of this medication’s side effects. Ask your doctor or pharmacist for more information.

Tell your doctor if you have any side effect that bothers you or that does not go away.

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

Tell your healthcare provider about all the medicines you take, including prescription and non-prescription medicines, vitamins and herbal supplements. Didanosine may affect the way other medicines work, and other medicines may affect how didanosine works.

Especially tell your healthcare provider if you take:

• Viread (tenofovir disoproxil fumarate)
• Droxia, Hydrea (hydroxyurea)
• Rescriptor (delavirdine mesylate)
• Cytovene, Valcyte (ganciclovir)
• Crixivan (indinavir)
• Dolophine Hydrochloride, Methadose (methadone)
• Viracept (nelfinavir)
• antacids
• antifungal medicines such as Nizoral (ketoconazole) or Sporanox (itraconazole)
• quinolone antibiotics such as Cipro, Proquin XR (ciprofloxacin)
• tetracycline antibiotics such as Bristacyclin, Sumycin (tetracycline)
• alcoholic beverages

Know the medicines you take. Keep a list of your medicines and show it to your healthcare provider and pharmacist when you get a new medicine.

Ask your healthcare provider if you are not sure if you take one of the medicines listed above.

Didanosine may cause serious side effects, including:

• Swelling of your pancreas (pancreatitis) that may cause death. Pancreatitis can happen at any time during your treatment with didanosine. Before you start taking didanosine, tell your healthcare provider if you:
  • have had pancreatitis
  • have advanced HIV (human immunodeficiency virus) infection
  • have kidney problems
  • drink alcoholic beverages
  • take a medicine called Zerit (stavudine)

It is important to call your healthcare provider right away if you have stomach pain, swelling of your stomach, nausea and vomiting, or fever.

• Build-up of acid in your blood (lactic acidosis). Lactic acidosis must be treated in the hospital as it may cause death. The risk for lactic acidosis may be higher if you:
  • have liver problems
  • are pregnant. There have been deaths reported in pregnant women who get lactic acidosis after taking didanosine and Zerit (stavudine).
  • are overweight
  • have been treated for a long time with other medicines to treat HIV

It is important to call your healthcare provider right away if you feel weak or tired, have unusual (not normal) muscle pain, have trouble breathing, have stomach pain with nausea and vomiting, feel cold, especially in your arms and legs, feel dizzy or light-headed, or have a fast or irregular heartbeat.

• Liver problems. Some people (including pregnant women) who have taken didanosine have had serious liver problems. These problems include liver enlargement (hepatomegaly), fat in the liver (steatosis), liver failure, and high blood pressure in the large vein of the liver (portal hypertension). Severe liver problems can lead to liver transplantation or death in some people taking didanosine. Your healthcare provider should check your liver function while you are taking didanosine. You should be especially careful if you have a history of heavy alcohol use or liver problems.

It is important to call your healthcare provider right away if you have:

• yellowing of your skin or the white of your eyes (jaundice)
• dark urine
• pain on the right side of your stomach
• swelling of your stomach
• easy bruising or bleeding
• loss of appetite
• nausea or vomiting
• vomiting blood or dark colored stools (bowel movements)

• Vision changes. You should have regular eye exams while you take didanosine.
• Peripheral neuropathy. Symptoms include: numbness, tingling, or pain in your hands or feet. This condition is more likely to happen in people who have had it before, in patients taking medicines that affect the nerves, and in people with advanced HIV disease. A child may not notice these symptoms. Ask your child’s healthcare provider for the signs and symptoms of peripheral neuropathy in children.
• Changes in your immune system (immune reconstitution syndrome). Your immune system may get stronger and begin to fight infections that have been hidden in your body for a long time. Tell your healthcare provider if you start having new or worse symptoms of infection after you start taking HIV medicine.
• Changes in body fat (fat redistribution). Changes in body fat have been seen in people who take antiretroviral medicines. These changes may include: more fat in or around your upper back and neck (buffalo hump), breasts or chest, trunk, and less fat in your legs, arms, or face.

​Do not take didanosine if you take:

• Zyloprim, Lopurin, Aloprim (allopurinol)
• Copegus, Rebetol, Ribasphere, Ribavirin, Virazole (ribavirin)

Do not drink alcohol while you take didanosine. Alcohol may increase your risk of getting pain and swelling of your pancreas (pancreatitis) or may damage your liver.

Medicines can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of didanosine, there are no specific foods that you must exclude from your diet.

Before you take didanosine, tell your healthcare provider if you:

• have or had kidney problems
• have or had liver problems (such as hepatitis)
• have or had persistent numbness, tingling, or pain in the hands or feet (neuropathy)
• have any other medical conditions
• are pregnant or plan to become pregnant
• are breastfeeding or plan to breastfeed

Tell your healthcare provider about all the medicines you take, including prescription and non-prescription medicines, vitamins and herbal supplements. 

Tell your doctor if you are pregnant or plan to become pregnant.

The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X, are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

This medication falls into category B. It is not known if didanosine will harm your unborn baby. Tell your healthcare provider right away if you become pregnant while taking didanosine. You and your healthcare provider will decide if you should take didanosine while you are pregnant.

There is a pregnancy registry for women who take antiviral medicines during pregnancy. The purpose of the registry is to collect information about the health of you and your baby. Talk to your doctor about how you can take part in this registry.

Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Do not breastfeed. It is not known if didanosine can be passed to your baby in your breast milk and whether it could harm your baby. Also, mothers with HIV should not breastfeed because HIV can be passed to the baby in the breast milk.

• Take didanosine exactly as your healthcare provider tells you to take it.
• Your healthcare provider will tell you how much didanosine to take and when to take it.
• Your healthcare provider may change your dose. Do not change your dose of didanosine without talking to your healthcare provider.
• Do not take didanosine with food. Take didanosine on an empty stomach at least 30 minutes before or 2 hours after you eat.
• Try not to miss a dose, but if you do, take it as soon as possible. If it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule.
• Some medicines should not be taken at the same time of day that you take didanosine. Check with your healthcare provider.
• If your kidneys are not working well, your healthcare provider will need to do regular blood and urine tests to check how they are working while you take didanosine. Your healthcare provider may also lower your dosage of didanosine if your kidneys are not working well.
• If you take too much didanosine, contact a poison control center or emergency room right away.

If you are using the extended-release capsules, swallow them whole; do not split, chew, crush, break, or dissolve them. Tell your doctor if you are unable to swallow the extended-release capsules whole.

Take this medication exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

The dose your doctor recommends may be based on the following:

• the condition being treated
• other medical conditions you have
• other medications you are taking
• how you respond to this medication
• your weight
• your height
• your age
• your gender

Videx (didanosine oral solution):

• For adults who weigh at least 60 kg (132 lbs.) the recommended dosage is 200 mg twice daily OR 400 mg once daily.
• For adults who weigh less than 60 kg (132 lbs.) the recommended dosage is 125 mg twice daily OR 250 mg once daily.
• For children (2 weeks old to 18 years old)
  • Between 2 weeks and 8 months old, the recommended dosing is 100 mg/m² twice daily.
  • For those greater than 8 months old, the recommended dosing is 120 mg/m2 twice daily but not to exceed the adult dose.

Videx EC (didanosine delayed-release capsules):

If you take too much this medication, call your healthcare provider or local Poison Control Center, or seek emergency medical attention right away.

• Store the didanosine liquid mixture in a tightly closed container in the refrigerator between 36° F to 46° F (2° C to 8° C) for up to 30 days.
• Safely throw away any unused didanosine liquid after 30 days.
• Store didanosine capsules at 68° to 77°F (20° to 25°C).
• Keep didanosine and all medicines out of the reach of children and pets.

Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your body's response to didanosine.

WARNING: PANCREATITIS, LACTIC ACIDOSIS and HEPATOMEGALY with STEATOSIS

Fatal and nonfatal pancreatitis has occurred during therapy with didanosine used alone or in combination regimens in both treatment-naive and treatment-experienced patients, regardless of degree of immunosuppression. 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 with the use of nucleoside analogues alone or in combination, including didanosine and other antiretrovirals. 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.