Brand Name: Videx & Videx EC

Common Name: didanosine, ddI

Class: nucleoside analog (also called nucleoside reverse transcriptase inhibitor, NRTI or nuke)

Standard dose: One 400 mg enteric coated (Videx EC) delayed-release capsule once-a-day, with adjustments for weight and when combined with Viread or Truvada. (Also available in 125 mg, 200 and 250 mg caps.) For the older formulation of Videx, standard dose is two 100 mg buffered tablets twice-a-day (or four tablets once daily). Videx is also available as a buffered powder for oral solution. Take Videx and Videx EC strictly on an empty stomach, 30 minutes before or two hours after food or drink, except water. Take missed dose as soon as possible, but do not double up on the next dose. Generic Videx EC now available.

AWP: $328.22 / month for EC

Manufacturer contact: Bristol-Myers Squibb, www.bmsvirology.com, 1 (800) 272–4878

AIDS Treatment Information Service: 1 (800) HIV–0440 (448–0440)

Potential side effects and toxicity: Peripheral neuropathy (tingling, burning, numbness or pain in the hands or feet) may go away once didanosine is stopped, but can be painful and permanently debilitating if not treated in time and occurs more frequently when used with Zerit. Upset stomach (nausea and vomiting), diarrhea, headache, and more rarely pancreatitis (inflammation of the pancreas) has also been reported. Other toxicities include eye changes and optic neuritis (inflammation of nerves in the eye). Have periodic eye exam by someone who is aware you are HIV-positive. Increased uric acid levels (indicating a number of disorders, including kidney damage and metabolic diseases), and insomnia are other potential side effects. Rare but potentially fatal toxicity with all NRTIs is pancreatitis (inflammation of the pancreas), hepatomegaly with steatosis (enlarged, fatty liver) and lactic acidosis (accumulation of lactate in the blood and abnormal acid-base balance). Lactic acidosis has been seen in patients taking NRTIs but is more common and more severe in women, people who are obese and people who have been taking nukes for a long time; and more common in people with liver disease, but can occur in people without a history of liver damage. People with lactic acidosis may experience persistent fatigue, abdominal pain or distension, nausea/vomiting, and difficulty breathing or shortness of breath; and enlarged, fatty liver.
People with a history of peripheral neuropathy, pancreatitis or heavy alcohol use should avoid didanosine. Pancreatitis can be life-threatening and may cause pain in the stomach and back, along with nausea, vomiting and blood in the urine. Risks for pancreatitis include: higher than recommended doses of NRTIs, advanced HIV, and alcohol use. Body fat redistribution/accumulation has also been reported with didanosine.

Potential drug interactions: The levels of didanosine are increased by 44–60% when given at the same time as Viread (tenofovir), therefore a dose reduction to 250 mg for Videx is recommended. See Viread page for new, possibly worrisome, information. The dose of didanosine may need to be increased when taken with methadone. The combined use of didanosine and zalcitabine (Hivid) is not recommended because of the higher incidence of peripheral neuropathy. Antineoplastics (anti-tumor treatment) such as AZT and hydroxyurea may increase risk of peripheral neuropathy. Combining didanosine with stavudine (Zerit) or with hydroxyurea (Hydrea), alcohol, Cytovene, or NebuPent may increase risk of pancreatitis. Also, Cytovene substantually increases didanosine levels. Videx should be taken on an empty stomach two hours apart from protease inhibitors, Tagamet, Nizoral, Sporanox and dapsone, and one hour apart from Rescriptor, while Videx EC can be taken with them, but still on an empty stomach. With Viread, it may be taken with a light snack (low-fat, 373 calories).

Tips: Study indicates Videx EC (compared to Videx) may have lower risk of peripheral neuropathy. Either drug taken with Zerit increases the risk of lipoatrophy (facial wasting). Swallow the capsules whole (don’t break open or bite/chew). The capsules eliminate the bad taste and texture of the tablets and the enteric coating reduces diarrhea. Absorption can be decreased by as much as 50% when taken with food, so always try to take on an empty stomach. Antacids containing magnesium or aluminum may cause adverse side effects if given at the same time as Videx tablets. If you have reduced kidney function, you may require a lower dose. Notify your doctor immediately if peripheral neuropathy is suspected.