Three companies have agreed to settle hundreds of lawsuits brought over the safety of their low-testosterone drugs, while AbbVie Inc. and Abbott Laboratories Inc., the defendants with the most cases, gear up for more trials.

More than 6,000 lawsuits are pending in federal court against drug manufacturers, claiming the low-testosterone medications caused heart attacks and blood clots. Two of the defendants—GlaxoSmithKline and Auxilium Pharmaceuticals, a subsidiary of Endo Pharmaceuticals plc—have reached settlements, according to court records and documents filed with the U.S. Securities and Exchange Commission. Trials against another defendant, Eli Lilly and Co., are on hold until March 31 due to a settlement reached in December. None of the companies have revealed how much the settlements were worth.