Vitamin A and Treatment
Early and sustained virologic responses to standard treatment for hepatitis C virus (HCV) infection were markedly improved when patients also received high doses of vitamin A, results of a small trial showed.
After 48 weeks of treatment with standard doses of pegylated interferon-alpha2b, ribavirin (Rebetol), and 30,000 IU/day of vitamin A, 61.7% of patients had achieved sustained virologic responses, compared with 42.9% of patients taking only the standard therapies without the vitamin, Shuichi Sato, MD, of Shimane University in Izumo , Japan , said here.
The addition of vitamin A also boosted early virologic response rates assessed after 12 weeks: 70% of patients taking vitamin A plus the standard drugs had no HCV genetic matter in circulation, whereas only about 40% of patients on standard therapy alone showed viral negativity at that point.
Despite the very high doses of vitamin A tested in the 42-patient trial -- the recommended daily intake of vitamin A in the U.S. ranges from 2,310 to 3,000 IU/day for adults -- Sato said it appeared to have no adverse effects in the trial.
"There is little or no risk in a high dose of vitamin A," he said at a press conference in advance of his formal presentation at Digestive Disease Week.
Sato and other researchers had reported in 2003 that retinoic acid compounds increased expression of interferon receptors on hepatoma cells in vitro. They followed that up last year with short-term clinical results suggesting that vitamin A increased the antiviral activity of interferon and ribavirin in patients with HCV infection.
At DDW, he will be presenting data on 42 patients who received a full course of PEG-interferon and ribavirin therapy in an open-label, multicenter study.
Patients with chronic hepatitis C were randomized to receive the high dose of vitamin A, or not, in addition to the standard therapy.
A little more than half the patients were men. Mean age was about 55 and 16 patients had previously received interferon treatment.
Study treatment lasted 48 weeks in most patients, although it was extended to 72 weeks in a few patients who achieved HCV negativity between weeks 12 and 36 of therapy.
About 5% of patients assigned to the vitamin A group and 10% of control patients failed to show a sustained response at week 48 but did achieve it by week 72, Sato reported.
Discontinuations were slightly more common in the vitamin A group but not significantly so: about 15% versus 10% in the control group.
Sato said a placebo-controlled trial is planned.
Press conference moderator Kelly Tappenden, PhD, of the University of Illinois in Urbana-Champaign, called the approach "promising" but said the findings need to be confirmed in a more rigorous study.
She said the very high vitamin A dose used in the trial was noteworthy and potentially a concern, as vitamin A is known to have toxic potential.
"They really need to look carefully at how to monitor the dosing schedule," Tappenden said. "It's an issue that needs to be sorted out for a practicing clinician who is not necessarily used to working with megadoses of vitamin A."
No external funding for the study was reported.
Sato and Tappenden reported no financial disclosures.
Primary source: Digestive Disease Week