Chronic hemorheological effects of the calcium antagonist nilvadipine in essential hypertension.

Because blood viscosity is significantly raised in patients with essential hypertension (EH), the hemorheological effects of a 4-month chronic treatment with the calcium antagonist nilvadipine (FK 235, 5-isopropyl-3-methyl-2-cyano-1,4-dihydro-6-methyl-4- (m-nitrophenyl)-3,5-pyridinedicarboxylate, CAS 75530-68-6) on elevated blood viscosity was investigated prospectively in patients with EH, and compared with those in normotensive individuals of similar age. Hemorheological parameters were measured in 13 patients with EH (mean 63.7 years), before and 16.3 weeks (mean) after treatment with 8 mg nilvadipine, twice a day, following a 2-week placebo period, and in 14 normotensive individuals (mean 65.8 years). Whole blood viscosity of 45.0-562.5 s-1 shear rates and corrected blood viscosity of low (45.0 s-1) and high (225.0 s-1) shear rates at standardised hematocrit (Ht) of 45%, plasma viscosity, Ht, serum albumin, and plasma fibrinogen were measured before and after drug treatment and compared with those in normotensive individuals. Whole-blood and plasma viscosities were measured by cone-plate viscometer. Systolic and mean blood pressures (BPs), whole blood viscosities (at low and middle shear rates), corrected blood viscosity (Ht 45% at a low shear rate), and plasma viscosity were higher in patients with EH than in normotensive individuals before medication (p < 0.001 to p < 0.01). All these parameters decreased significantly after nilvadipine (p < 0.004 to p < 0.05). On the other hand, serum albumin and plasma fibrinogen were not altered significantly after nilvadipine. Ht decreased but not significantly after nilvadipine. Mean BP correlated with corrected blood viscosities at 112.5 s-1 and 225.0 s-1 (r = 0.491 p < 0.01 and r = 0.537 p < 0.005), while systolic BP did not correlate, before and after nilvadipine. Chronic treatment with calcium antagonist nilvadipine brought about significant reductions in BPs and rheological parameters of whole-blood viscosities at low and middle shear rates, corrected blood viscosity (Ht 45%) at a low shear rate, and plasma viscosity without changes in serum albumin and plasma fibrinogen levels, as compared with normotensive individuals. Significant linear correlations between values of mean BP and corrected blood viscosities before and after milvadipine show improved hemorheology in association with BP reduction in EH. Vasodilative effects of nilvadipine may have improved the blood rheology in patients with EH.