Effect of nimodipine on blood pressure in acute ischemic stroke in humans.

Nimodipine is currently under investigation for the treatment of acute stroke. Although relatively specific for the cerebrovasculature, acute reductions in blood pressure after a dose may adversely affect neurologic outcome. We studied 29 consecutive acute ischemic stroke patients treated with placebo (n = 9) or either 120 (n = 10) or 240 (n = 10) mg/day of nimodipine. Blood pressure was recorded before and 30 and 60 minutes after a dose for the first 8 days. Ten neurologic physicians were asked to predict the treatment group (placebo or drug) of randomly selected patients based on blood pressure results. Only those patients on 240 mg/day of nimodipine had significant decreases in blood pressure after a dose (p less than 0.001); however, these were minimal (average 10 mm Hg systolic). Only 26 of 48 treatment predictions (54%) were correct. At the studied doses, nimodipine has a minimal effect on blood pressure in the acute stroke period.

Characterization of the dose-concentration-dependent hemodynamic effects of nifedipine in heart failure.

The hemodynamic effects of increasing oral doses of nifedipine (10 to 30 mg) were studied in 12 patients who had low output heart failure. With each set of hemodynamics, serum concentrations of nifedipine were measured to determine the concentration/response relationships. Eleven of twelve patients responded acutely to nifedipine, defined as a reduction in systemic vascular resistance (SVR), and an augmentation in cardiac index (CI) and stroke volume index (SVI). The differential dose effects (X +/- SD) for SVR and SVI for baseline (N = 11), 10 mg (N = 10), 20 mg (N = 3) and 30 mg (N = 4) were: 1913 +/- 486, 1102 +/- 221, 1128 +/- 166, 803 +/- 176 and 17.9 +/- 4.8, 23.8 +/- 4.5, 31 +/- 0.42, 33 +/- 3.5, respectively. All nifedipine doses reduced SVR and increased CI and SVI compared with baseline (P less than .001). The increase in CI and SVI was significantly correlated to the mg/kg dose of nifedipine (r = 0.79; P less than .001). Nifedipine administration resulted in no significant change in central venous pressure, pulmonary capillary wedge pressure, or pulmonary vascular resistance. No relationship could be demonstrated between serum concentrations of nifedipine and any hemodynamic effect. Conclusions drawn were: (1) the afterload reduction effects of nifedipine are acutely efficacious in a large portion of patients with heart failure and this activity supercedes the negative inotropic effects of the drug at doses between 10 and 30 mg; (2) the magnitude of the hemodynamic effects are dose dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

Integration of pharmacokinetics and pharmacodynamics of methicillin in curative treatment of experimental endocarditis.

The rabbit model for Staphylococcus aureus endocarditis was used to compare cure rate and pharmacokinetic profile of four dosing regimens of methicillin. Equal daily doses (120 mg/kg) in five day treatment periods were given to 40 rabbits. Doses were given by bolus 20 mg/kg every 4 h (q 4 h), 40 mg/kg every 8 h (q 8 h), 60 mg/kg every 12 h (q 12 h) or by continuous infusion. The methicillin pharmacokinetics resulting from each regimen were monitored along with the course of the infection in each rabbit. For each regimen, time above MBC, peak height, area under the curve (AUC) above MIC and MBC were measured. Post antibiotic effect (PAE) duration and log growth time (LGT) values were obtained from the literature. Significantly more rabbits treated by q 4 h and q 8 h (P less than 0.05) survived 14 days after cessation of methicillin treatment than did rabbits treated q 12 h or continuous infusion. The four regimens differed in peak concentration and time above MBC. Despite producing the highest peak concentrations, the q 12 h regimen was the least effective. The duration above MBC was 2.0, 1.5, and 0.6 hours for q 12 h, q 8 h and q 4 h regimens, respectively. Continuous infusion produced methicillin concentration just above MBC over the entire five day treatment period, but was not as effective as q 4 h or q 8 h regimens. The most successful intermittent bolus regimens were those in which the sum of time above MBC, the duration of PAE, and one LGT were approximately equal to the actual dosage interval.