duration of action
plasma level-effect relation
Springer Online Journal Archives 1860-2000
Chemistry and Pharmacology
Summary The concentration-beta blocking effect and time-effect relationships of carteolol were examined in eight normal adults given 15 mg i.v. and 20 mg orally on separate occasions. Resting and post-exercise blood pressures and heart rates were assessed before and at various times up to 48 h after each dose. Carteolol, a β-blocker with some partial agonist activity, produced an insignificant, transient increase in heart rate 2 to 6 h after both doses, and a fall (p〈0.05) in diastolic blood pressure 4 and 6 h after the intravenous dose and 6 h after the oral dose in the resting supine position, as compared to the corresponding baseline values. All values of the post-exercise heart rate and the double product after each of the doses were significantly (p〈0.001) below the baseline values for the entire period (48 h) of observation. A significant correlation between the log plasma carteolol concentration (log C) and its beta-blocking effect (E: p〈0.001, r=0.508 i.v.; p〈0.001, r=0.626, p.o.) was found. The r-values for individuals were higher (0.852 to 0.977, intravenous; 0.817 to 0.981, oral) than for the group as a whole. The slope (m) of the relationship, E=m·log C+r, showed a certain variance within and between individuals. When the absolute reduction in exercise-induced heart rate was plotted against time and the rate of decline of effect (Rd) and duration of action were estimated from the time-effect relationship, the mean Rd values were 0.655 and 0.462 beats/min per h, and for the duration of action they were 83.8 and 123.9 h after the intravenous and oral doses, respectively. The effect declined at a slower rate (p〈0.02) and the duration of beta-blockade was longer (p〈0.01) after the oral dose.
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