pressant

Pressant is a term used in physiology and pharmacology to denote a substance that raises systemic blood pressure, i.e., a pressor. In contemporary medical writing the more common terms are pressor, vasopressor, or vasoconstrictor; pressant is encountered mainly in older texts or in broader discussions of agents that elevate blood pressure.

Mechanism and examples: Pressants raise blood pressure by vasoconstriction, increasing peripheral resistance, boosting cardiac output, or promoting fluid retention. Classic pressants include catecholamines such as adrenaline (epinephrine) and noradrenaline (norepinephrine), phenylephrine, and other agents like angiotensin II and vasopressin. Some agents have mixed effects; for example, vasopressors used in shock therapy may also have inotropic effects increasing cardiac function.

Clinical use and safety: Pressants are used to treat hypotension during anesthesia, septic shock, or volume depletion when nonpharmacologic measures are insufficient. They require careful monitoring of blood pressure, heart rate, and organ perfusion, and carry risks such as excessive vasoconstriction, hypertension, myocardial ischemia, arrhythmias, and reflex bradycardia.

Etymology and usage notes: The word derives from press, with the suffix -ant denoting an agent that performs the action. In modern pharmacology the term pressant is uncommon; practitioners typically refer to vasopressors or pressors when describing drugs that raise blood pressure.