| Popis: |
A single administration of verapamil (5 mg infused intravenously) and nifedipin (20 mg sublingually) in 31 patients with chronic cardiac failure of stage I and IIA decreased the levels of ionizing calcium (Ca2+) in the blood serum (the maximum reduction averaged 19.8% and 16.8%, respectively). The total concentration of calcium (Ca0) in the blood serum did not alter, so the degree of ionization of the serum calcium (Ca2+/Ca0) decreased. This effect was felt 5 min after verapamil administration and 15 min after nifedipin administration, generally reaching the peak in 30 min and somewhat subsiding in 60 min. The nature and time-course of changes of Ca0 and Ca2+ in the blood serum following the drug administration suggest that they are induced by a transient increase in the Ca-binding capacity of the serum buffers, i. e. they are realized on the physicochemical level. This effect shows no tendency to cumulate following a prolonged (1.3-15 months) administration of the above drugs. The coefficients of the paired correlation between the shifts in the Ca2+ content on the one hand and hemodynamic parameters on the other indicate no significant correlation between them. However, the author believes that the consistent decrease in the Ca2+ concentration in the blood serum is involved in the pharmacodynamics of verapamil and nifedipin. |
