Sciele Pharma is making a $6 million investment in Addrenex Pharmaceuticals, a startup launched last year, and could buy even more of the company later.

Sciele, which is based in Atlanta, also signed on to market a proposed drug by Addrenex called Clonicel that targets hypertension and attention deficit disorder as well as hyperactivity.

As part of the deal, Sciele has the option to buy an additional 10 percent in Addrenex. It also will pay Addrenex milestone payments up to as much as $11 million.

Addrenex is seeking to commercialize a patented oral, extended-release drug formulation to combat symptoms associated with excessive adrenaline secretion. The firm has also received a $175,000 in loans from the North Carolina Biotechnology Center.

Sciele also gained the right of first refusal to market other Addrenex products.

Addrenex plans to file a new drug application with the Food and Drug Administration later this year. A Phase III clinical trial is also planned.

“This agreement with Addrenex provides us with the opportunity to further expand both our cardiovascular and pediatric product lines,” said Sciele Chief Executive Officer Patrick Fourteau.

Sciele focuses on sales, marketing and development of drugs focused on cardiovascular ailments, diabetes, women’s health and pediatrics.