Generic drugmaker

Ivax

(IVX)

said Friday that it has received conditional approval from U.S. drug regulators to sell a generic version of the diabetes drug Glucophage.

But it might take an act of Congress, not just the Food and Drug Administration, to give the Miami-based drugmaker final clearance to actually sell the drug. That's because

Bristol-Myers Squibb

(BMY) - Get Report

is doing everything it can to retain exclusive U.S. rights to Glucophage -- one of its top moneymakers, with 2000 sales of almost $1.8 billion.

Shares of Ivax were up $1.24, or 6%, to $20.94 in Friday trading. The company says final approval will come from the FDA once issues involving use of Glucophage in children are resolved.

But these issues of "pediatric labeling" are thorny and complicated, illustrating the lengths to which pharmaceutical firms will go to protect valuable drug franchises.

Strictly speaking, Bristol-Myers should have already lost patent protection over Glucophage. But the company conducted tests of the drug in children, which gave it another six months of protection, according to federal law.

But the FDA used the results of these tests to approve the drug for use in children in February. Now, Bristol-Myers is arguing that it should be granted another three years of exclusivity, based on two other federal laws. The first of these gives drug companies another three years of protection when the FDA approves a drug for a new use. The second requires labels for generic drugs to be identical to those on the brand-name versions.

Simply put, Bristol-Myers is trying to convince the FDA that it should prohibit generic Glucophage from hitting the market until 2004 because it conducted tests that allow the drug to be used by children. The generic drugmakers haven't conducted these tests, so they can't match the claims and won't be able to include them on the drug's label.

Children, in this case people under the age of 18, make up just 0.3% of Glucophage customers.

Bristol-Myers has extended its fight for Glucophage to Congress, which is currently trying to draft legislation that would clarify the pediatric testing issue.

Ivax is not the only generic drugmaker with a stake in this fight. Another dozen firms also have applied to the FDA to sell copycat versions of the drug, including

Barr Labs

(BRL)

,

Andrx

(ADRX)

and

Mylan Labs

(MYL) - Get Report

.

For its part, Bristol-Myers has been hit hard with patent expirations on some of its biggest-selling products, including the cancer-fighter Taxol and the antianxiety drug BuSpar. Earlier this month, a federal appeals court ruled in favor of Bristol-Myers in a dispute over Taxol, stating that the FDA should not have allowed Ivax to sell a generic version of the drug. Ivax has said it intends to fight the decision.

Shares of Bristol-Myers fell 55 cents to $78.02 Friday. Raymond James drug analyst Raymond Krensavage downgraded the drugmaker to market perform from strong buy, stating that the FDA's decision to conditionally approve generic Glucophage would hurt profits. Raymond James doesn't have a banking relationship with Bristol-Myers.