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

Phase 1
Completed
Conditions
Muscle Relaxation
Sex
Interventions
Registration Number
NCT01906528
Lead Sponsor
University of California, San Francisco
Brief Summary

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.

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.

Recruitment & Eligibility

Status
COMPLETED
Sex
All
Target Recruitment
20
Inclusion Criteria

Healthy individuals with no current medication -

Exclusion Criteria

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

Study & Design

Study Type
INTERVENTIONAL
Study Design
SINGLE_GROUP
Arm && Interventions
GroupInterventionDescription
Males vs femalesMivacuriumConstant-rate IV infusions of Mivacurium, range 1.0 - 3 micro/kg/min, duration 150 - 180 min
Primary Outcome Measures
NameTimeMethod
Pharmacodynamics of Mivacurium6 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
NameTimeMethod
Clearance of Mivacurium6 months

Clearance calculated as the relationship between steady-state infusion rate of Mivacurium and Mivacurium blood concentration.

Trial Locations

Locations (1)

University of California, UCSF

🇺🇸

San Francisco, California, United States

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