hypotension

hypotension is abnormally low blood pressure, especially in the arteries of the systemic circulation. It is best understood as a physiologic state, rather than a disease. It is often associated with shock, though not necessarily indicative of it. Hypotension is the opposite of hypertension, which is high blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. If it is lower than normal then it is called low blood pressure or hypotension. Hypotension is generally considered as systolic blood pressure less than 90 millimeters of mercury (mm Hg) or diastolic less than 60 mm Hg. However in practice, blood pressure is considered too low only if noticeablesymptoms are present.


Drugs that activate alpha adrenergic receptors in vascular smooth muscle increase peripheral resistance and maintain or elevate blood pressure. These agents may be useful for the treatment of orthostatic hypotension. 

Midodrine is a prodrug that is converted to a direct–acting α₁-agonist after oral administration. The activation of α₁receptors causes arterial and venous smooth muscle contraction resulting in a rise in blood pressure. Supine hypertension is a frequent complication associated with midodrine. This side effect can be minimized by avoiding dosing prior to bedtime. Cautious use of a short-acting antihypertensive agent at bedtime may also be helpful.