A Recirculatory Model for Pharmacokinetics and the Effects on Bispectral Index After Intravenous Infusion of the Sedative and Anesthetic AZD3043 in Healthy Volunteers

ABSTRACT Meropenem is a broad-spectrum carbapenem antibacterial agent. In order to optimize levels in plasma relative to the MICs, the ideal dose level and dosage regimen need to be determined. The pharmacokinetics of meropenem were studied in two groups, each comprising eight healthy volunteers who received the following doses: 500 mg as an intravenous infusion over 30 min three times a day (t.i.d.) versus a 250-mg loading dose followed by a 1,500 mg continuous infusion over 24 h for group A and 1,000 mg as an intravenous infusion over 30 min t.i.d. versus a 500-mg loading dose followed by a 3,000-mg continuous infusion over 24 h for group B. Meropenem concentrations in plasma and urine were determined by liquid chromatography-mass spectrometry/mass spectrometry and high-performance liquid chromatography with UV detection, respectively. Pharmacokinetic calculations were done by use of a two-compartment open model, and the data were extrapolated by Monte Carlo simulations for 10,000 simulated subjects for pharmacodynamic evaluation. There were no significant differences in total clearance and renal clearance between group A and group B or between the intermittent treatment and the continuous infusion. The analyses of the probability of target attainment by MIC for the high- and low-dose continuous infusions were robust up to MICs of 4 mg/liter and 2 mg/liter, respectively. The corresponding values for intermittent infusions were only 0.5 mg/liter and 0.25 mg/liter. When these observations were correlated with MICs obtained from the MYSTIC database, intermittent infusion results in adequate activity against two of the most common nosocomially acquired pathogens, Klebsiella pneumoniae and Enterobacter cloacae. However, against Pseudomonas aeruginosa, the evaluation shows a clear advantage of high-dose therapy administered as a continuous infusion. We believe that in the empirical therapy situation, the continuous-infusion mode of administration is most worth the extra efforts. We conclude that clinical trials for evaluation of the continuous infusions of meropenem in critically ill patients are warranted.

Download Full-text

Two-hour infusion of vasoactive intestinal polypeptide induces delayed headache and extracranial vasodilation in healthy volunteers

Cephalalgia ◽

10.1177/0333102420937655 ◽

2020 ◽

Vol 40 (11) ◽

pp. 1212-1223 ◽

Cited By ~ 1

Author(s):

Lanfranco Pellesi ◽

Mohammad Al-Mahdi Al-Karagholi ◽

Basit Ali Chaudhry ◽

Cristina Lopez Lopez ◽

Josefin Snellman ◽

...

Keyword(s):

Healthy Volunteers ◽

Intravenous Infusion ◽

Superficial Temporal Artery ◽

Area Under The Curve ◽

Temporal Artery ◽

Continuous Intravenous Infusion ◽

Headache Intensity ◽

Parasympathetic System ◽

The Difference ◽

Cranial Arteries

Background In recent years, vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptides (PACAPs) have gained special interest in headache science. VIP and PACAPs (two isoforms, PACAP27 and PACAP38) are related in structure and function, as are their receptors, but they show differences in vasodilating- and headache-inducing properties. Intravenous infusion of PACAP27 or PACAP38, but not VIP, induces a long-lasting dilation of cranial arteries and delayed headache. The relationship between the long-lasting cranial vasodilation and headache development is not fully clarified. Methods In a double-blinded, placebo-controlled, crossover study in 12 healthy volunteers, diameter changes of cranial arteries, occurrence of headache and the parasympathetic system were examined before, during and after a 2-hour continuous intravenous infusion of VIP and placebo. Primary endpoints were the differences in area under the curve for the superficial temporal artery diameter and headache intensity scores, as well as in headache incidence, between VIP and placebo. Results The superficial temporal artery diameter was significantly larger on the VIP day compared to placebo ( p < 0.001) and the dilation lasted for more than 2 h. The incidence of headache was higher ( p = 0.003) on the VIP day compared to the placebo day. The difference in headache intensity scores was more evident in the post-infusion period (120–200 min, p = 0.034) and in the post-hospital phase (4–12 h, p = 0.025). Cranial parasympathetic activity, measured through the production of tears, was higher during VIP compared to placebo ( p = 0.033). Conclusion Continuous intravenous infusion of VIP over 2 h induced a long-lasting cranial vasodilation, activation of the cranial parasympathetic system, and delayed mild headaches in healthy volunteers. Trial Registration: The study is registered at ClinicalTrials.gov (NCT03989817).

Download Full-text