Central and peripheral haemodynamic effects of non-steroidal anti-inflammatory drugs in man

The haemodynamic effects of non-steroidal anti-inflammatory (NSAI) drugs can be attributed either to their common property of inhibiting the formation of prostaglandins (PG) in the cardiovascular system, or to direct actions on the tone and sensitivity of the resistance vessels in various regions. Indomethacin (IND) is the most frequently studied NSAI drug, in animals and in man. Its cardiovascular effects differ somewhat from those of other NSAI, due to the fact that, besides inhibiting PG formation, IND acts as a direct vasoconstrictor. The stimulatory effect of IND in vascular smooth muscle results in an increased systemic vascular resistance which, although partially compensated by a decreased cardiac output, gives rise to a moderate increase in systemic blood pressure. The vasoconstrictor effect of IND is of particular interest in patients with ischemic heart disease, since it lowers their already decreased coronary flow, and may thereby accentuate the risk of myocardial infarction. Administration of IND also leads to a decreased blood flow in the splanchnic region, the kidneys, and the brain. The cerebral blood flow is lowered by 25-35%; in addition, IND almost entirely erases the hyperemic flow response to hypercapnia. Of other NSAI drugs, at least aspirin and naproxen are completely devoid of such actions on the cerebral circulation. A common vascular effect of all NSAI drugs is a diminution of reactive hyperemia, the local hyperemia that develops in a tissue subjected to a short period of arterial occlusion. Part of this hyperemic response is dependent on an intact vascular PG formation and consequently it is inhibited when PG formation is blocked. In contrast, NSAI drugs do not affect the functional increase in the blood flow in working skeletal muscle.