The R-enantiomer of the racemic synthetic agent modafinil with central nervous system (CNS) stimulant and wakefulness-promoting activities. Although the exact mechanism of action has yet to be fully elucidated, armodafinil appears to inhibit the reuptake of dopamine by binding to the dopamine-reuptake pump, which leads to an increase in extracellular dopamine levels in some brain regions. This agent does not bind to or inhibit several receptors and enzymes that may be involved in sleep/wake regulation and is not a direct- or indirect-acting dopamine receptor agonist. Armodafinil has a longer half-life than modafinil. OR A drug used to prevent blood clots from forming inside blood vessels in the leg. It is being studied in the prevention of blood clots in some cancer patients, including women having surgery for cancer of the reproductive tract. It is a type of anticoagulant. Also called fondaparinux and fondaparinux sodium.