Videx EC

Videx EC is part of the drug class:

• Nucleoside and nucleotide reverse transcriptase inhibitors

You should not use didanosine if you are allergic to it.

Do not take didanosine together with allopurinol (Zyloprim, Lopurin, Aloprim) or ribavirin (Rebetol, Ribasphere, Copegus, Virazole).

Some people taking didanosine develop a serious condition called lactic acidosis. This may be more likely in women, in people who are overweight or have liver disease, and in people who have taken HIV/AIDS medication for a long time. Talk with your doctor about your risk.

To make sure didanosine is safe for you, tell your doctor if you have:

• liver disease or a history of pancreatitis (didanosine can cause severe or life-threatening effects on your liver or pancreas);

• kidney disease;

• a history of numbness or tingling in your hands or feet, including Raynaud's syndrome;

• if you drink large amounts of alcohol; or

• if you also take stavudine (Zerit).

If you are pregnant, do not take didanosine together with stavudine. This combination of medicines can cause lactic acidosis or liver problems, which can be very dangerous during pregnancy.

HIV can be passed to your baby if you are not properly treated during pregnancy. Take all of your HIV medicines as directed to control your infection. Your name may be listed on a pregnancy registry. This is to track the outcome of the pregnancy and to evaluate any effects of didanosine on the baby.

Women with HIV or AIDS should not breast feed a baby. Even if your baby is born without HIV, the virus may be passed to the baby in your breast milk.

In the U.S.

• Videx
• Videx EC
• Videx Pediatric

Available Dosage Forms:

• Powder for Suspension
• Tablet, Chewable
• Powder for Solution
• Capsule, Delayed Release

Therapeutic Class: Antiretroviral Agent

Pharmacologic Class: Nucleoside Reverse Transcriptase Inhibitor

• It is used to treat HIV infection.

• If your symptoms or health problems do not get better or if they become worse, call your doctor.
• Do not share your drugs with others and do not take anyone else's drugs.
• Keep a list of all your drugs (prescription, natural products, vitamins, OTC) with you. Give this list to your doctor.
• Talk with the doctor before starting any new drug, including prescription or OTC, natural products, or vitamins.
• This medicine comes with an extra patient fact sheet called a Medication Guide. Read it with care. Read it again each time this medicine is refilled. If you have any questions about Videx EC, please talk with the doctor, pharmacist, or other health care provider.
• If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about Videx EC. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from the healthcare provider. You must talk with the healthcare provider for complete information about the risks and benefits of using Videx EC.

Review Date: October 4, 2017

VIDEX® EC (didanosine, USP), also known as ddI, in combination with other antiretroviral agents is indicated for the treatment of human immunodeficiency virus (HIV)-1 infection [see Clinical Studies (14)].

Established Drug Interactions

Clinical recommendations based on the results of drug interaction studies are listed in Table 5. Pharmacokinetic results of drug interaction studies are shown in Tables 9-12 [see Contraindications (4.1 and 4.2), Clinical Pharmacology (12.3)].

Exposure to didanosine is increased when coadministered with tenofovir disoproxil fumarate [Table 5 and see Clinical Pharmacokinetics (12.3, Tables 9 and 10)]. Increased exposure may cause or worsen didanosine-related clinical toxicities, including pancreatitis, symptomatic hyperlactatemia/lactic acidosis, and peripheral neuropathy. Coadministration of tenofovir disoproxil fumarate with Videx EC should be undertaken with caution, and patients should be monitored closely for didanosine-related toxicities and clinical response. Videx EC should be suspended if signs or symptoms of pancreatitis, symptomatic hyperlactatemia, or lactic acidosis develop [see Dosage and Administration (2.3), Warnings and Precautions (5)]. Suppression of CD4 cell counts has been observed in patients receiving tenofovir disoproxil fumarate with didanosine at a dose of 400 mg daily.

Predicted Drug Interactions

Predicted drug interactions with Videx EC are listed in Table 6.

There is no known antidote for didanosine overdosage. In phase 1 studies, in which buffered formulations of didanosine were initially administered at doses ten times the currently recommended dose, toxicities included: pancreatitis, peripheral neuropathy, diarrhea, hyperuricemia, and hepatic dysfunction. Didanosine is not dialyzable by peritoneal dialysis, although there is some clearance by hemodialysis [see Clinical Pharmacology (12.3)].

Carcinogenesis, Mutagenesis, Impairment of Fertility

Lifetime carcinogenicity studies were conducted in mice and rats for 22 and 24 months, respectively. In the mouse study, initial doses of 120, 800, and 1200 mg/kg/day for each sex were lowered after 8 months to 120, 210, and 210 mg/kg/day for females and 120, 300, and 600 mg/kg/day for males. The two higher doses exceeded the maximally tolerated dose in females and the high dose exceeded the maximally tolerated dose in males. The low dose in females represented 0.68-fold maximum human exposure and the intermediate dose in males represented 1.7-fold maximum human exposure based on relative AUC comparisons. In the rat study, initial doses were 100, 250, and 1000 mg/kg/day, and the high dose was lowered to 500 mg/kg/day after 18 months. The upper dose in male and female rats represented 3-fold maximum human exposure.

Didanosine induced no significant increase in neoplastic lesions in mice or rats at maximally tolerated doses.

Didanosine was positive in the following genetic toxicology assays: 1) the Escherichia coli tester strain WP2 uvrA bacterial mutagenicity assay; 2) the L5178Y/TK+/- mouse lymphoma mammalian cell gene mutation assay; 3) the in vitro chromosomal aberrations assay in cultured human peripheral lymphocytes; 4) the in vitro chromosomal aberrations assay in Chinese Hamster Lung cells; and 5) the BALB/c 3T3 in vitro transformation assay. No evidence of mutagenicity was observed in an Ames Salmonella bacterial mutagenicity assay or in rat and mouse in vivo micronucleus assays.

Animal Toxicology and/or Pharmacology

Evidence of a dose-limiting skeletal muscle toxicity has been observed in mice and rats (but not in dogs) following long-term (greater than 90 days) dosing with didanosine at doses that were approximately 1.2 to 12 times the estimated human exposure. The relationship of this finding to the potential of didanosine to cause myopathy in humans is unclear. However, human myopathy has been associated with administration of didanosine and other nucleoside analogues.

More frequent side effects include: pancreatitis. See below for a comprehensive list of adverse effects.