Related Experiment Video
Updated: Jul 14, 2026

Objective Nociceptive Assessment in Ventilated ICU Patients: A Feasibility Study Using Pupillometry and the Nociceptive Flexion Reflex
Published on: July 4, 2018
Effective dose of nefopam in 80% of patients (ED80): a study using the continual reassessment method
Hélène Beloeil1, Mathilde Eurin, Aude Thévenin
1A. P.-H. P. Hôpital Bicêtre, Département d'Anaesthésie-Réanimation, F-94275, Le Kremlin-Bicêtre, University Paris-Sud, Laboratoire d'anaesthésie, Faculté de Médecine de Bicêtre, F-94275, Le Kremlin-Bicêtre, France.
Aims:
The effective dose in 50% of patients (ED(50)) is far from being relevant for clinical purposes. We used the continual reassessment method (CRM) to determine the effective dose of nefopam in 80% of the patients suffering from moderate pain in the postoperative period (ED(80)).
Methods:
Patients with a pain intensity >3 on a 1-10 numerical pain score (NPS) received increasing or decreasing doses of nefopam (20, 30, 40, 60, 80 mg) postoperatively. The criterion of success was a NPS
Results:
Twenty-four patients were enrolled. Nefopam 60 mg gave a probability of success of 0.818 (95% credibility interval 0.606-0.941). Using the maximum likelihood technique, we determined an ED(50) of 27.3 mg and a dose leading to a probability of 0.8 (ED(80)) of 74.4 mg. We did not observe a high incidence of side-effects.
Conclusions:
The ED(80) of nefopam, close to 60 mg is higher than the usual dose of 20 mg. The CRM allowed us to determine the ED(80) of nefopam with reasonable accuracy in a small number of patients as compared with the classical dose-probability curve fitting. We did not observe an increased incidence of side-effects when compared with the literature or to our previous studies.
Related Concept Videos
Time Course of Drug Effect
Impact of Pharmacokinetic–Pharmacodynamic Models: Regulatory Decisions
Renal Failure: Dose Adjustments
Reduced renal clearance and elimination rate are common outcomes of renal impairment. These alterations lead to a prolonged elimination half-life and an altered apparent volume of distribution for drugs. As a result, dosage adjustments are typically necessary to maintain optimal drug levels in the body.
However, dosage adjustments...
Dosage Regimens: Partial Pharmacokinetic Parameters
Drug Dosing in Renal Diseases: Dose Adjustments Based on Drug Clearance and Elimination Rate Constant
Dose-Response Relationship: Potency and Efficacy