The Influence of Dexmedetomidine Added to Ropivacaine on Its Pharmacokinetic and Pharmacodynamic Effects During Lumbar Plexus Block
Authors' conclusion
Our research demonstrated that dexmedetomidine significantly influences the pharmacokinetics and pharmacodynamics of ropivacaine in LPB.
Study context
- Population
- Patients undergoing unilateral lower limb surgery under lumbar plexus block
- Participants
- 46 patients
- Comparison
- Ropivacaine plus perineural dexmedetomidine 0.25 or 0.5 µg·kg −1 vs ropivacaine alone for lumbar plexus block
Methodological detailsprospective, population pharmacokinetic modelling
- Prospective
- Population pharmacokinetic modelling
Primary result
As reported in the abstract
Ropivacaine pharmacokinetics and pharmacodynamics
Dexmedetomidine 0.5 µg·kg −1 vs ControlMean difference, µg·mL -1 (95% CI)P value
Reduced maximum ropivacaine concentration
0.8(0.5–1.2)
P < 0.0001Dexmedetomidine 0.5 µg·kg −1 vs ControlDifference, L (95% CI)P value
Increased apparent volume of distribution
33.1(13.4–52.8)
P = 0.013Dexmedetomidine 0.5 µg·kg −1 vs ControlDifference, minutes (95% CI)P value
Prolonged time to maximum concentration
5(1–9)
P = 0.011Reduced onset time of sensory blockade
5(2–6)
P < 0.0001Extended duration of sensory blockade
175(55–294)
P = 0.005Further findings
Simulated toxic ropivacaine dose for lumbar plexus blocks (LPB), body weight 56 to 76 kg
- With 0.5 µg·kg −1 dexmedetomidine: modeled toxic dose decreased from 4.9 to 3.0 mg·kg −1
- Without dexmedetomidine: modeled toxic dose decreased from 3.3 to 2.1 mg·kg −1
- Toxicity threshold 4.3 ± 0.6 µg·mL −1 (mean ± SD)
Original publication
The Influence of Dexmedetomidine Added to Ropivacaine on Its Pharmacokinetic and Pharmacodynamic Effects During Lumbar Plexus Block. Anesth Analg. Published 24 November 2025. doi:10.
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