EXPAREL Dose-Response for Single-Injection Femoral Nerve Blocks
EXPAREL™, an investigational drug product, is a new formulation of a local anesthetic (numbing medicine) that is designed to be longer acting than the currently-available local anesthetics. The purpose of this study is to determine the effect on thigh muscle strength and skin sensitivity of various doses of EXPAREL when placed next to the nerve that goes to the thigh.
|Study Design:||Allocation: Randomized
Endpoint Classification: Pharmacodynamics Study
Intervention Model: Single Group Assignment
Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
|Official Title:||EXPAREL Dose-Response for Single-Injection Femoral Nerve Blocks: A Pharmacodynamics Investigation in Healthy Volunteers|
- Quadriceps femoris muscle strength [ Time Frame: For the 10 hours after the nerve blocks are placed, the left and right thighs will be tested as described below. ] [ Designated as safety issue: No ]While seated, participants will be asked to push their right foot forward against a machine which gives resistance (as if they were kicking slowly), and this machine will measure the strength in their thigh muscles.
- Sensory level [ Time Frame: For the 10 hours after the nerve blocks are placed, the left and right thighs will be tested as described below. ] [ Designated as safety issue: No ]Two small electrode pads are placed near the top of one knee cap; and a small electrical current increased until the participant feels slight discomfort. These procedures will be repeated on the other side as well.
|Study Start Date:||February 2012|
|Study Completion Date:||April 2012|
|Primary Completion Date:||April 2012 (Final data collection date for primary outcome measure)|
Experimental: Nerve Block
The dominant side (left or right) will be randomized to one of two treatment groups: the higher or lower concentration of the local anesthetic EXPAREL. The non-dominant contralateral side will receive the other possible treatment. The volume of each and every single-injection femoral nerve block will be 30 mL (standard for femoral nerve blocks is 30-40 mL).3 Since volume will remain constant, we will vary the dose of EXPAREL by varying concentration (volume x concentration = dose). Of note, EXPAREL may be mixed with normal saline to vary the concentration. Randomization will be based on computer-generated codes. Randomization will be in blocks of two, and stratified by sex.
Single-injection femoral nerve block. Initial doses of SKY0402 will begin at 0 mg, and 2 mg (high) for the first subject; and 1 mg (low) and 3 mg (high) for the second subject. The next doses will be between 0-80 mg per side, determined prior to randomization of each subsequent subject. The specific subsequent doses will increase, remain the same, or decrease, determined by the P.I. in consultation with the manufacturer of SKY0402. Doses will always remain within the range of 0-80 mg per side, for a total possible dose of 0-160 mg.
Other Name: EXPAREL
Putting local anesthetic next to a nerve is a common way of decreasing the pain that patients feel after surgery. For knee surgery, the local anesthetic is placed next to the femoral nerve in the middle of the crease where the leg meets the body when bending at the hip joint. However, the local anesthetic takes away not only sensation—and therefore pain—but also motor control, leaving muscles weaker. It would greatly improve patient safety if the investigators could administer a very long-acting local anesthetic that decreased postoperative pain, but affected muscle strength only minimally. Currently, the investigators do not know if this is possible with EXPAREL, and the investigators therefore are conducting this study to help determine the dose of EXPAREL that will result in a minimal (20%) decrease in muscle strength.