Pharmacokinetic–Pharmacodynamic Correlation of Sedatives and Analgesics in Critical Care Settings: A Quantitative Bioanalytical Study

The components of intensive care management could not live without sedation and
analgesia, but the optimal pharmacological balance of patients who are in critical care is still
complex because of physiological variability and drug metabolism modifications. This
research involves the pharmacokinetic pharmacodynamic (PKPD) interactions between
midazolam, fentanyl and propofol in order to determine quantitative relations between
plasma concentrations and clinical outcomes. A case of a prospective observational study
was aimed at 100 patients in the ICU who were given midazolam (n=34), fentanyl (n=33) or
propofol (n=33) continuous infusions. Validated liquid chromatography-tandem mass
spectrometry (LC-MS/MS) was used to analyse serum plasma samples and was followed
with FDA bioanalytical standards (bias older 5 per cent, CV decreased 7 per cent). At the
same time, the appraisal of sedation and analgesia was evaluated by means of the Richmond
Agitation sedation Scale (RASS) and Critical-Care Pain Observation Tool (CPOT). Noncompartmental and Spearman rank were used to statistically analyse pharmacokinetic and
PKPD correlations. The three agents all had concentration-dependent pharmacodynamic
effects with significant negative relationships between plasma concentrations and
RASS/CPOT scores (midazolam ρ = -0.88; fentanyl rho = -0.79; propofol rho = -0.74; p<
0.001). Under constant infusion, predictable pharmacokinetic behavior was observed, with
steady-state concentrations being attained in 1216hours. Quantitative PK -PD relationships
using LC-MS/MS confirm that plasma drug concentration is a strong predictor of sedation
and the depth of analgesia. The results indicate the accuracy of dosing and tailored sedation
regimens in the critical care unit to reconcile bioanalytical exactness with clinical
pharmacology towards optimum healing results.