Brand name: Videx EC and Videx
Generic name: didanosine, or ddI
Class: Nucleoside reverse transcriptase inhibitor (nucleoside, NRTI, or nuke)
Manufacturer: Bristol-Myers Squibb, www.bms.com, (800) 321-1335
AWP: $425.00/month for Videx EC 400 mg capsules (generic didanosine $329.00/month)
Standard Dose: One 400 mg enteric-coated Videx EC, delayed-release capsule once a day for people who weigh 132 pounds or more. Dose needs to be adjusted for those weighing less than 132 pounds; kidney function less than 60 mL/min; and when combined with Viread, Truvada, or Atripla. Take strictly on an empty stomach (unless taking with Viread), one hour before or two hours after food or drink, except water. Approved for children weighing at least 44 pounds. Take missed dose as soon as possible, unless it is closer to the time of your next dose. Do not double up on your next dose. Capsules must be swallowed whole. Videx is also available as a buffered powder for oral solution. Generic Videx EC (didanosine EC) is available.
Potential side effects and toxicity: Peripheral neuropathy (tingling, burning, numbness, or pain in the hands or feet) may go away once Videx EC is stopped, but can be painful and permanently debilitating if not treated in time or if you continue to use Videx EC after symptoms of neuropathy start. It occurs more frequently when Videx EC is used with Zerit or in people with more advanced HIV. Upset stomach, diarrhea, headache, and, more rarely, pancreatitis (inflammation of the pancreas), have also been reported. 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. Stop all HIV medications and see a health care provider right away. Recent post-marketing surveillance has reported cases of non-cirrhotic portal hypertension (increased blood pressure in the vessels that connect to and from the liver) associated with the use of Videx EC. Symptoms (elevated liver enzymes, enlarged spleen, blood in vomit, and fluid collection in abdomen) may begin months to years after starting Videx EC. Routine doctor visits and lab tests will assist in early detection and prompt discontinuation of Videx EC. Other possible toxicities include eye changes and optic neuritis. Have periodic eye exams 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. People with a history of peripheral neuropathy, pancreatitis, or heavy alcohol use should avoid Videx EC. Body fat redistribution/accumulation has also been reported with Videx EC. See chart for potential drug class side effects.
Potential drug interactions: Should not be taken with Viread (tenofovir), if possible. However, if co-administration is necessary, use tenofovir with caution and close monitoring, since Videx EC levels are increased with tenofovir (a medication also found in Atripla, Complera, and Truvada). Videx EC dose should be decreased to 250 mg daily for patients weighing more than 132 lbs. and 200 mg daily for those weighing less. Adjust dose of Videx EC when taking Viread, Truvada, Atripla, or Complera to avoid Videx-related toxicity, including neuropathy and pancreatitis. The combined use of Videx and Retrovir (zidovudine), Zerit, or hydroxyurea may increase risk of peripheral neuropathy. Videx EC taken with Zerit increases the risk of facial wasting and/or lactic acidosis. Combining Videx EC with Zerit, hydroxyurea, alcohol, ganciclovir, valganciclovir, or intravenous (not inhaled) pentamidine may increase risk of pancreatitis. Do not take with ribavirin or allopurinol. Also, ganciclovir substantially increases Videx EC levels, and is generally recommended not to be taken together. If there is no alternative to ganciclovir, use it with caution and monitor for Videx EC toxicity. Videx powder in oral solution should be taken on an empty stomach one hour before or two hours after protease inhibitors, Tagamet (cimetidine), ketoconazole, itraconazole, and dapsone, and one hour apart from Rescriptor. Videx EC capsules 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). Methadone decreases Videx powder concentrations significantly and should not be used together, but if necessary, the Videx EC capsule formulation should be used.
More information: Videx EC is rarely used. Videx EC compared to Zerit may have lower risk of peripheral neuropathy, but the rate found in clinical trials was still 12-34%. This is hardly an issue anymore, since Zerit is even more rarely used (if ever). Swallow the capsules whole. The enteric coating reduces diarrhea compared to the previous formulation. If you have reduced kidney function, you may require a lower dose. Notify your doctor right away if peripheral neuropathy is suspected. See package insert for more complete information on potential side effects and interactions.
Videx (ddI), approved in 1991, was our second antiretroviral drug. People often used it after AZT stopped working. Later it was added to AZT in our primitive attempts at early combination therapy. It was a complicated drug to take, requiring twice-daily dosing on an empty stomach, and sometimes involving the use of powder formulations or the mixing of crushed tablets with antacids to improve tolerability. The new EC (enteric coated) formulation eliminates those problems, but this is no longer a drug with much of a purpose. Its resistance patterns overlap with the better tolerated tenofovir and abacavir, and it causes neuropathy, pancreatitis, and probably lipoatrophy. More recently, questions have been raised about whether ddI might cause non-cirrhotic portal hypertension, an uncommon but serious and potentially fatal liver condition that doesn't get better after you stop taking the drug.
-- Joel Gallant, M.D., M.P.H.
Is there anyone out there still on this drug? There may be a handful of folks still using this, but it is mainly a relic of HIV treatment history. Too many toxic side effects for me to tolerate it back in the day, but Jeff Taylor said it best in last year's rundown; "The fact that it's rarely used anymore can work in its favor, making it a useful add-on drug to salvage regimens for patients who've exhausted all other options." Other than that, I can't see much use.
-- Joey Wynn