The U.S. Food and Drug Administration has asked Tenax Therapeutics Inc. to conduct another clinical trial of its main drug, according to a filing Friday with the Securities and Exchange Commission.

The drug, levosimendan, is designed to treatment patients undergoing coronary artery bypass grafting to reduce the risk of low cardiac output syndrome and to treat patients with acute decompensated heart failure.

“Given the size and scope of such a trial, the company is reviewing clinical, regulatory and financial options with regard to the levosimendan program in the U.S. and Canada,” said the Morrisville, North Carolina-based company in a statement.

The drug is available in 60 other countries. Tenax acquired the North American rights from Phyxius Pharma.

In April, the company’s chief executive officer resigned and Tenax began a comprehensive review of strategic alternatives to current operations, a process that could result in the company being acquired.

Tenax said Friday that the review of alternatives is continuing.

Tenax shares fell more than 75 percent in late January after the company announced disappointing phase 3 trial results for levosimendan. The company, however, said it continues to believe the drug is safe and effective.

Tenax shares closed Friday at 69 cents.