didanosine (ddI, Videx, Videx EC) a Simple FactSheet from the AIDS Treatment Data Network

||||| Videx is a Nucleoside Reverse Transcriptase Inhibitor:

didanosine, trade name Videx (also known as ddI), is an anti-HIV treatment in a class of drugs called nucleoside analogs. The body breaks down these drugs into chemicals that stop HIV from infecting uninfected cells in the body, but they do not help cells that have already been infected with the virus. As people with HIV lose CD4 cells - one of the immune system's main defenses - they become more likely to get infections and illnesses. Videx is an important part of combination anti-HIV treatment. Ideally, Videx should be used as part of a carefully chosen combination of anti-HIV treatments in order to get the most benefit. Studies have shown that when taken alone Videx has a strong anti-HIV effect at first, but the virus can quickly become resistant. The anti-HIV effects may then wear out. Many studies have now shown that using Videx in combination with at least two other anti-HIV drugs can prevent the virus from getting resistant. This has helped people live longer and develop less opportunistic infections. Drug resistance tests (genotypic or phenotypic) have been shown to be useful in choosing the best anti-HIV treatment regimen specific to an individual. See the FactSheets "Combination Therapy" & "Understanding Drug Resistance" for a detailed discussion on these subjects. New Public Health Service HIV treatment guidelines say that the best way to use Videx is in combination with other anti-HIV drugs. The guidelines recommend combinations of three or four anti-HIV drugs as first treatment for HIV. The recommended combinations should take one drug or combo from column A and one combo from column B (Drugs are listed in alphabetical, not priority order): Recommendation Column A Column B Strongly Recommended Sustiva Crixivan Viracept Norvir + Crixivan Kaletra Norvir + Fortovase Videx + Epivir Videx + Zerit Epivir + Zerit Videx + Retrovir Epivir + Retrovir Recommended as Alternatives Ziagen Agenerase Rescriptor Viracept + Fortovase Viramune Norvir Fortovase Retrovir + HIVID Not recommended because of insufficient data hydroxyurea in combo with ARVs Norvir + Agenerase Norvir + Viracept Viread Not Recommended and should not be offered Invirase Zerit + Retrovir HIVID + Videx HIVID + Epivir HIVID + Zerit There have been encouraging results from studies of Videx in combination with an old anti-cancer drug called hydroxyurea. However, recent information indicate an increased risk of liver and pancreatic toxicity using this combination, especially when they are also combined with stavudine.

||||| Dosage:

Videx usually comes in the form of a large, flavored tablet that can be chewed or dissolved in water, or in a powder that gets dissolved in water. A smaller, mandarin-flavored tablet is also available. This new tablet is softer and dissolves in water faster than the old tablet. Because food can slow down the body's absorption of Videx, people should take the drug at least half an hour before, or two hours after eating. The recommended adult dose of Videx is based on body weight. People weighing over 132 pounds should take 200mg twice daily while those weighing less than 132 pounds should take 125mg twice daily. Tablets are available in 25, 50, 100 and 150 mg dosages. At least two of the appropriate strength tablets should be taken at each dose, normally in the morning and evening. Although some people take the entire dose of Videx once a day, this has not been proven to be as effective as the twice a day regimen.

||||| Videx EC:

A new once a day formulation for Videx was approved by the FDA in 2000. It is called Videx EC. It comes in capsules containing enteric coated Videx. The capsules should be swallowed whole, once a day. Studies have suggested that it is similarly effective as the older tablets. Videx EC capsules can pass through the stomach without being affected by the stomach acids. It has less drug interactions than the older tablets, as it does not contain the antacid buffer that caused absorption problems with other drugs. A new study suggests that Videx EC should be taken on an empty stomach, as food drastically affects Videx levels in the blood. It should be taken at least 1 and a half hours before a meal, or two hours after. If you are taking Videx EC with tenofovir (Viread), the level of Videx in your blood can be increased by up to 60%, this can lead to more severe side effects.

||||| Side effects:

The most common side effects reported are stomach pain, diarrhea, peripheral neuropathy and pancreatitis. Peripheral neuropathy is a kind of nerve damage that shows up as a burning or tingling pain in the hands and feet. Pancreatitis can appear as a pain in the stomach area that goes through to your back. If pancreatitis isn't caught soon enough, it can be very serious. Careful monitoring of blood enzymes called amylase and lipase can provide an early warning of pancreatitis. If you're taking Videx avoid alcohol, which can increase the risk of pancreatitis. Recent studies have also suggested that taking Videx in combination with stavudine (d4T,Zerit) and/or hydroxyurea may increase the risk of pancreatitis. Note: The FDA has issued a revised warning letter to doctors regarding pancreatitis and Videx. Letter to Doctors regarding better results with twice daily dosing.

||||| Warnings:

A set of rare but serious side effects of nucleoside analog anti-HIV drugs is called lactic acidosis and severe hepatomegaly with steatosis (an enlarged fatty liver). Women, especially those who are oveweight, are particularly at risk. This set of side effects is probably the result of mitochondrial toxicity. Mitochondria are cell's power organs that supply the energy needed for normal cell growth. Anti-HIV nucleoside analogs impair the function of mitochondria. This can lead to increased acid levels in the blood, and an enlarged fatty liver. The symptoms are severe nausea, shortness of breath and vomiting that does not get better. If you are taking anti-HIV drugs and experience these symptoms, tell your provider immediately.

||||| Drug interactions:

Make sure your medical provider knows what other drugs you are taking, as Videx has many drug interactions. Videx significantly lowers the levels of ciprofloxacin, dapsone, ketoconazole, and quinolones (such as ofloxacin) in the body. These drugs should be taken two hours before or after taking Videx. Ganciclovir significantly increases the level of Videx in the body, these drugs should be taken two hours apart. If you're taking Videx and the protease inhibitor indinavir (Crixivan) or the NNRTI drug delavirdine (Rescriptor), or the new NtRTI tenofovir (Viread), you should take these drugs at least an hour before Videx. Videx should not be combined with zalcitabine (ddC, HIVID). If you are taking intravenous pentamidine for PCP at the same time as Videx, there is an increased risk of pancreatitis. Methadone decreases the level of Videx by 52% in the blood. You should avoid taking Videx with the drug allopurinol as this drug significantly increases Videx levels in the body. Because Videx pills contain antacid, you should not take additional antacids when using Videx.

||||| Using children's Videx:

There is a version of Videx for children. Children's Videx comes in cherry or mint flavor and must be mixed with an antacid (Mylanta DS Liquid or extra strength Maalox Plus suspension or Maalox TC suspension). Some adults find the children's version of Videx easier to take than the tablets. For adults, children's Videx can be mixed by a pharmacist to give a strength of 20mg of Videx per milliliter of liquid. This way, 20 milliliters (mL) of children's Videx will provide the usual daily adult Videx dose of 400mg. If you're having trouble taking Videx tablets, ask your doctor about trying the children's version. Bristol-Myers Squibb, who makes Videx and Videx EC, has Reimbursement Assistance and Temporary Assistance Programs for people having trouble affording the drug. Call (800) 272-4878 for more information.To find out if a drug is covered by your state's AIDS Drug Assistance Program or Medicaid, call The Access Project at 212-260-8868 or 800-734-7104.

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