Sex-related Differences in the Response to the Muscle Relaxant Drug Mivacurium
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.
|Study Design:||Endpoint Classification: Safety/Efficacy Study
Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Treatment
|Official Title:||The Pharmacodynamics of Mivacurium in Males and Females: A Study in Human Volunteers|
- Pharmacodynamics of Mivacurium [ Time Frame: 6 months ] [ Designated as safety issue: No ]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.
- Clearance of Mivacurium [ Time Frame: 6 months ] [ Designated as safety issue: No ]Clearance calculated as the relationship between steady-state infusion rate of Mivacurium and Mivacurium blood concentration.
- Relationship between thumb acceleration (TOF ratio) and handgrip strength in both sexes [ Time Frame: 6 months ] [ Designated as safety issue: No ]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.
|Study Start Date:||March 2013|
|Study Completion Date:||July 2013|
|Primary Completion Date:||July 2013 (Final data collection date for primary outcome measure)|
Experimental: Males vs females
Constant-rate IV infusions of Mivacurium, range 1.0 - 3 micro/kg/min, duration 150 - 180 min
Effect of Mivacurium in males vs females
Other Name: Mivacron
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.
|United States, California|
|University of California, UCSF|
|San Francisco, California, United States, 94131|
|Principal Investigator:||John R Feiner, MD||University of California, UCSF, San Francisco, USA|