Acute and chronic renal effects of guanfacine in essential and renal hypertension.

1. Antihypertensive drugs may influence renal function, due to haemodynamic effects and altered release of hormones. 2. Acute and chronic renal effects (glomerular filtration rate (GFR) renal plasma flow (CPAH); diuresis; electrolyte clearances (CNa+, CK+, CCa++, CPO4 3-) of guanfacine have been investigated. 3. Acute intravenous injection induced a marked decrease in GFR, renal blood flow, diuresis and electrolyte clearances. These effects were less pronounced after oral administration. 4. In long-term antihypertensive treatment these effects are less prominent. 5. EFfects of guanfacine on blood pressure and heart rate are similar to those of clonidine (initial pressor response and bradycardia after intravenous injection).