METAP2 and Thromboembolism: Other medications such as sibutramine, a norepinephrine and serotonin inhibitor, lorcaserin, a serotonin 2C receptor agonist, and beloranib, a methionine aminopeptidase 2 (MetAP2) inhibitor, were discontinued due to significant adverse events of thromboembolism and other safety concerns (14).