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Sex-related Differences in the Response to the Muscle Relaxant Drug Mivacurium

This study has been completed.
Oslo University Hospital
Information provided by (Responsible Party):
University of California, San Francisco Identifier:
First received: July 17, 2013
Last updated: April 9, 2014
Last verified: April 2014
Muscle relaxants are drugs providing muscle relaxation during surgical treatment. Previous studies have shown that males and females respond differently to this kind of drug. Our hypothesis is that males are more sensitive to the effect of Mivacurium (a muscle relaxant) than females, meaning that males need a lower blood concentration of the drug than females in order to obtain a given effect.

Condition Intervention Phase
Muscle Relaxation Sex Drug: Mivacurium Phase 1

Study Type: Interventional
Study Design: Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: The Pharmacodynamics of Mivacurium in Males and Females: A Study in Human Volunteers

Resource links provided by NLM:

Further study details as provided by University of California, San Francisco:

Primary Outcome Measures:
  • Pharmacodynamics of Mivacurium [ Time Frame: 6 months ]
    The mivacurium drug concentration in the blood associated with 50% of maximal drug effect at steady-state conditions (Css50) will be determined at the thumb and the handgrip muscles.

Secondary Outcome Measures:
  • Clearance of Mivacurium [ Time Frame: 6 months ]
    Clearance calculated as the relationship between steady-state infusion rate of Mivacurium and Mivacurium blood concentration.

Other Outcome Measures:
  • Relationship between thumb acceleration (TOF ratio) and handgrip strength in both sexes [ Time Frame: 6 months ]
    Thumb acceleration secondary to nerve stimulation at the ulnar nerve (TOF ratio) is an objective way of monitoring the effect of muscle relaxants that is used frequently during clinical anesthesia. Handgrip strength will be monitored with a dynamometer.

Enrollment: 20
Study Start Date: March 2013
Study Completion Date: July 2013
Primary Completion Date: July 2013 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Males vs females
Constant-rate IV infusions of Mivacurium, range 1.0 - 3 micro/kg/min, duration 150 - 180 min
Drug: Mivacurium
Effect of Mivacurium in males vs females
Other Name: Mivacron

Detailed Description:
Muscle relaxants are a type of drug used to provide muscle relaxation during induction of anesthesia and surgical treatment. Residual drug effect postoperatively (i.e. residual muscle relaxation) occurs frequently and studies have shown that this may be harmful in certain groups of patients. Of special concern is residual effect on upper airway and breathing muscles. A previous study has shown that males and females respond differently to the effect of this kind of drug. It appears that some muscle groups which are important for airway protection and breathing are more sensitive to the effect of muscle relaxants in males than females. Males may therefore be more susceptible to postoperative lung complications than females. In this study we try to determine what causes the observed sex-related difference in response to the muscle relaxant Mivacurium. We have previously shown that this sex-related difference cannot be explained by different pharmacokinetics (what the body does to the drug) in males and females. Our hypothesis is that a pharmacodynamic (what the drug does to the body) difference between sexes exists, i.e. that a lower blood concentration of Mivacurium is needed in males than females in order to obtain a predefined degree of muscle relaxation in certain muscle groups.

Ages Eligible for Study:   18 Years to 45 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria: Healthy individuals with no current medication -

Exclusion Criteria: Previous complications during anesthesia, pregnancy, allergy to muscle relaxants, smoking, gastrointestinal reflux.

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Please refer to this study by its identifier: NCT01906528

United States, California
University of California, UCSF
San Francisco, California, United States, 94131
Sponsors and Collaborators
University of California, San Francisco
Oslo University Hospital
Principal Investigator: John R Feiner, MD University of California, UCSF, San Francisco, USA
  More Information

Responsible Party: University of California, San Francisco Identifier: NCT01906528     History of Changes
Other Study ID Numbers: IRB11-07970
Study First Received: July 17, 2013
Last Updated: April 9, 2014

Keywords provided by University of California, San Francisco:
Nondepolarizing neuromuscular blocking drug

Additional relevant MeSH terms:
Neuromuscular Nondepolarizing Agents
Neuromuscular Blocking Agents
Neuromuscular Agents
Peripheral Nervous System Agents
Physiological Effects of Drugs processed this record on September 25, 2017