Interest Renewed in AIDS Test Drug Made by O.C. Firm : Treatment: The FDA remains skeptical of isoprinosine, despite impending publication of a favorable Scandinavian study in a prestigious journal.

Interest in an all but forgotten experimental AIDS drug, isoprinosine--manufacturered by Newport Pharmaceuticals International Inc. of Laguna Hills--has been renewed by the New England Journal of Medicine’s decision to publish a favorable Scandinavian study of the medication.

“Treatment with isoprinosine appears to delay progression to AIDS” in infected individuals, Dr. Court Pedersen of the University of Copenhagen said Tuesday at a medical meeting held in conjunction with the Sixth International Conference on AIDS.

But officials of the U.S. Food and Drug Administration are skeptical of the findings. In an editorial that will be published in the New England Journal Thursday along with the study, FDA officials said “a confirmatory study (is) mandatory before claims of efficacy can be accepted.”

As news of the journal publication was made public Tuesday, the company’s stock jumped 81.25 cents to $3.625 per share. The 28.9% gain was the second largest percentage gain in over-the-counter trading Tuesday.

Before the completion of the Scandinavian study, there was so little data supporting isoprinosine’s effectiveness against AIDS that Newport Pharmaceuticals had planned to abandon its testing program. Other studies conducted in the United States and Britain have shown no benefit.

Isoprinosine is believed to boost the function of immune system cells and help them ward off the ravages of the AIDS virus. It does not appear to act directly against the human immunodeficiency virus (HIV), the cause of AIDS.

The 831-person study was conducted in Denmark and Sweden between 1986 and 1988. The participants were mostly HIV-infected white gay men who had yet to become ill.

The study showed that patients who took three isoprinosine tablets a day for 24 weeks developed AIDS at a significantly lower rate than patients randomly assigned to take placebo tablets, said Pedersen, who directed the research.

Of the approximately 400 patients in each group, AIDS, the most advanced stage of HIV infection, developed in two in the isoprinosine group as compared to 17 in the placebo group. No serious side effects were observed.

But other results were less convincing. For example, no significant differences were found in progression to many pre-AIDS conditions, such as weight loss and diarrhea.

Pedersen also acknowledged that the drug failed to restore immune function and that the amount of AIDS virus in the bloodstream did not change. In fact, in both groups of patients the concentration of T-4 white blood cells, which are destroyed by the AIDS virus, decreased significantly.

Judith Archbold, a Newport Pharmaceuticals vice president, said the company “can’t really undertake additional studies until we can get support and endorsement from the AIDS research community. We are hopeful that the publication will be helpful in getting that support.”

Pedersen said: “If there are no new studies, I don’t think isoprinosine treatment has any future.”