Chronic Pain
Conditions
Brief summary
The primary goal of this protocol is to model change in oxytocin concentrations in plasma after intravenous (IV) administration. Additional measurements will be performed on sensory function that could be influenced by oxytocin during later time periods when blood samples are widely separated by time. This protocol will describe the pharmacokinetics (PK) of intravenous oxytocin in healthy adult men and adult,non-pregnant women. PK samples will be obtained after an injection of intravenous oxytocin 10 IU over 60 seconds. Blood will be drawn for the PK samples prior to the oxytocin administration and then 11 times after administration. There are two additional measures which will assess two different aspects of sensory function. MEASURE 1: Light Touch Frequency Threshold In order to determine the highest frequency that specific nerve fibers can respond to, a simple device that produces an oscillatory / vibratory stimulus will be used on the hand. The subject places fingertips, palm, and palm side of the wrist sequentially and the device is set to slowly decrease the frequency of vibration from 1 kHz until the subject first perceives this. This is repeated three times at each site and takes less than 5 minutes in total. This will be performed before the oxytocin administration and 6 times after the administration of IV Oxytocin. MEASURE 2: Sustained Heat The surface of the skin of the forearm or leg is heated to 113°F using a computer controlled thermode for a period of 5 minutes. This will be done before the IV Oxytocin and 4 times after the administration. A set of random thermal temperatures (98°F-122°F) will also be applied to the skin of the leg or forearm before the IV Oxytocin administration and 4 times after administration of IV Oxytocin.
Detailed description
The primary goal of this protocol is to model change in oxytocin concentrations in plasma after intravenous administration, (oxytocin (Pitocin®), 10 IU) the investigators will also acquire tests of sensory function that could be modulated by oxytocin during later time periods when blood samples are widely separated by time. There are two measures which will assess two different aspects of sensory function. MEASURE 1: Light Touch Frequency Threshold Light touch is subserved by a group of myelinated peripheral nerves with fast conduction in the Aβ range and which are capable of following high frequencies, being responsible for the sensation of vibration. This capability of individual nerve fibers to respond with high frequency also underlies our ability to sense a light touch moving across the body surface as in brushing. In preclinical studies investigators have shown that, following injury, these light touch fibers lose their ability to follow high frequencies and, in some cases, no longer respond to mechanical stimulation at all. Oxytocin, when perfused around the neuronal cell bodies of these Aβ nerve fibers, partially restores their function, including their response to high frequency stimulation. In order to determine the highest frequency that Aβ nerve fibers can respond to, the investigators have created a simple device that produces an oscillatory / vibratory stimulus which can be used on the hand. The subject places fingertips, palm, and volar aspect of the wrist sequentially and the device is set to slowly decrease the frequency of vibration from 1 kilohertz (kHz) until the participant first perceives this. This is repeated three times at each site and takes under 5 minutes in total. The investigators anticipate that oxytocin will have no effect on normal Aβ fibers and that this measure will not change after oxytocin administration. This will provide important data to contrast with the expected efficacy of oxytocin in the setting of injury, to be studied in subsequent protocols. MEASURE 2: Sustained Heat As part of a protocol used by the investigators in several studies, the surface of the skin of the forearm or leg is heated to 45°C using a computer-controlled thermode for a period of 5 minutes. This typically results in a slowly increasing pain experience, peaking at 5 minutes in the mild to low moderate range and has been tolerated by more than 150 subjects in studies over the past 14 years. In an interim analysis of an ongoing clinical study in volunteers, the investigators noted that spinal injection of oxytocin, 15 μg (equivalent to 9 IU), that pain from this sustained heat was dramatically reduced over the 5 minutes of stimulus presentation. In contrast, spinal oxytocin had no effect on the stimulus-response relationship of pain to noxious heat over a 42-50°C range when the stimuli were presented for only 5 seconds. These data suggest that oxytocin reduces C-fiber mediated signaling of sustained heat pain, likely through a spinal site of action. Drugs administered spinally have a much higher concentration in cerebrospinal fluid than plasma. Nonetheless, spinally administered drugs are typically absorbed to an extent and with a time course similar to that after intramuscular injection, and it is conceivable that the effect on sustained heat pain investigators are seeing in the spinal study reflect peripheral effects via systemic absorption. Thus, if the investigators see a similar reduction in response to sustained heat in this protocol of intravenous administration, the investigators will conclude that oxytocin is more likely activating peripherally than spinally.
Interventions
DRUGOxytocin
Single IV administration of oxytocin
Sponsors
Wake Forest University Health Sciences
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE
Intervention model description
Single intravenous administration of oxytocin (Pitocin®), 10 IU
Eligibility
Sex/Gender
ALL
Age
18 Years to 60 Years
Healthy volunteers
Yes
Inclusion criteria
* Male or female \> 18 and \< 60 years of age, Body Mass Index (BMI) \<40. * Generally in good health as determined by the Principal Investigator based on prior medical history, American Society of Anesthesiologists physical status I or II * Normal blood pressure (systolic 90-140 mmHg; diastolic 50-90 mmHg) resting heart rate 45-100 beats per minute) without medication * Female subjects of child-bearing potential and those \< 1 year post-menopausal, must be practicing highly effective methods of birth control such as hormonal methods
Exclusion criteria
* Hypersensitivity, allergy, or significant reaction to any ingredient of Pitocin® * Any disease, diagnosis, or condition (medical or surgical) that, in the opinion of the Principal Investigator, would place the subject at increased risk (active gynecologic disease in which increased tone would be detrimental e.g., uterine fibroids with ongoing bleeding), compromise the subject's compliance with study procedures, or compromise the quality of the data * Women who are pregnant (positive result for serum pregnancy test at screening visit), women who are currently nursing or lactating, women that have been pregnant within 2 years * Subjects with neuropathy, chronic pain, diabetes mellitus, or taking benzodiazepines or pain medications on a daily basis.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Oxytocin Concentration | 2 minutes | Plasma concentrations of oxytocin at defined times after intravenous infusion |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Light Touch Frequency Threshold | 5 minutes | The frequency at which the vibration is perceived after intravenous oxytocin administration |
| Sustained Heat | 31 minutes | 0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome. |
Countries
United States
Participant flow
Pre-assignment details
None. All enrolled subjects completed the study.
Participants by arm
| Arm | Count |
|---|---|
| Oxytocin (Pitocin®), 10 IU Oxytocin 10 IU administered once per intravenous injection
Oxytocin: Single IV administration of oxytocin | 11 |
| Total | 11 |
Baseline characteristics
| Characteristic | Oxytocin (Pitocin®), 10 IU |
|---|---|
| Age, Continuous | 38 years STANDARD_DEVIATION 13 |
| BMI | 29 kg/m^2 STANDARD_DEVIATION 3.4 |
| Ethnicity (NIH/OMB) Hispanic or Latino | 0 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 11 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Height | 173 cm STANDARD_DEVIATION 6.5 |
| Light Touch Frequency Threshold | 731 Hz STANDARD_DEVIATION 155 |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants |
| Race (NIH/OMB) Asian | 0 Participants |
| Race (NIH/OMB) Black or African American | 0 Participants |
| Race (NIH/OMB) More than one race | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Race (NIH/OMB) White | 11 Participants |
| Region of Enrollment United States | 11 participants |
| Sex: Female, Male Female | 6 Participants |
| Sex: Female, Male Male | 5 Participants |
| Sustained heat Five minutes | 1.32 units on a scale STANDARD_DEVIATION 0.3 |
| Sustained heat Four minutes | .82 units on a scale STANDARD_DEVIATION 0.25 |
| Sustained heat One minute | .36 units on a scale STANDARD_DEVIATION 0.21 |
| Sustained heat Three minutes | .64 units on a scale STANDARD_DEVIATION 0.29 |
| Sustained heat Two minutes | .68 units on a scale STANDARD_DEVIATION 0.32 |
| Weight | 86 kg STANDARD_DEVIATION 11 |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | 0 / 11 |
| other Total, other adverse events | 7 / 11 |
| serious Total, serious adverse events | 0 / 11 |
Outcome results
Primary
Oxytocin Concentration
Plasma concentrations of oxytocin at defined times after intravenous infusion
Time frame: 2 minutes
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Oxytocin Concentration | 1047 pg/ml | Standard Deviation 556 |
Primary
Oxytocin Concentration
Plasma concentrations of oxytocin at defined times after intravenous infusion
Time frame: 10 minutes
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Oxytocin Concentration | 322 pg/ml | Standard Deviation 136 |
Primary
Oxytocin Concentration
Plasma concentrations of oxytocin at defined times after intravenous infusion
Time frame: 15 minutes
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Oxytocin Concentration | 202 pg/ml | Standard Deviation 91 |
Primary
Oxytocin Concentration
Plasma concentrations of oxytocin at defined times after intravenous infusion
Time frame: 30 minutes
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Oxytocin Concentration | 82 pg/ml | Standard Deviation 40 |
Primary
Oxytocin Concentration
Plasma concentrations of oxytocin at defined times after intravenous infusion
Time frame: 45 minutes
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Oxytocin Concentration | 41 pg/ml | Standard Deviation 20 |
Primary
Oxytocin Concentration
Plasma concentrations of oxytocin at defined times after intravenous infusion
Time frame: 60 minutes
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Oxytocin Concentration | 25 pg/ml | Standard Deviation 13 |
Primary
Oxytocin Concentration
Plasma concentrations of oxytocin at defined times after intravenous infusion
Time frame: 90 minutes
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Oxytocin Concentration | 10 pg/ml | Standard Deviation 5.6 |
Primary
Oxytocin Concentration
Plasma concentrations of oxytocin at defined times after intravenous infusion
Time frame: 120 minutes
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Oxytocin Concentration | 6.2 pg/ml | Standard Deviation 3.6 |
Primary
Oxytocin Concentration
Plasma concentrations of oxytocin at defined times after intravenous infusion
Time frame: 180 minutes
Population: In 7 subjects oxytocin concentration was below the limit of detection (1 pg/ml)
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Oxytocin Concentration | 2.5 pg/ml | Standard Deviation 1.6 |
Primary
Oxytocin Concentration
Plasma concentrations of oxytocin at defined times after intravenous infusion
Time frame: 240 minutes
Population: In 9 subjects oxytocin concentration was below the limit of detection (1 pg/ml)
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Oxytocin Concentration | 1.0 pg/ml | Standard Deviation 1.5 |
Primary
Oxytocin Concentration
Plasma concentrations of oxytocin at defined times after intravenous infusion
Time frame: 5 minutes
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Oxytocin Concentration | 587 pg/ml | Standard Deviation 257 |
Secondary
Light Touch Frequency Threshold
The frequency at which the vibration is perceived after intravenous oxytocin administration
Time frame: 5 minutes
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Light Touch Frequency Threshold | 722 Hz | Standard Deviation 141 |
p-value: 0.89ANOVA
Secondary
Light Touch Frequency Threshold
The frequency at which the vibration is perceived after intravenous oxytocin administration
Time frame: 20 minutes
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Light Touch Frequency Threshold | 710 Hz | Standard Deviation 130 |
Secondary
Light Touch Frequency Threshold
The frequency at which the vibration is perceived after intravenous oxytocin administration
Time frame: 180 minutes
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Light Touch Frequency Threshold | 771 Hz | Standard Deviation 99 |
Secondary
Light Touch Frequency Threshold
The frequency at which the vibration is perceived after intravenous oxytocin administration
Time frame: 45 minutes
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Light Touch Frequency Threshold | 732 Hz | Standard Deviation 128 |
Secondary
Light Touch Frequency Threshold
The frequency at which the vibration is perceived after intravenous oxytocin administration
Time frame: 60 minutes
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Light Touch Frequency Threshold | 727 Hz | Standard Deviation 127 |
Secondary
Light Touch Frequency Threshold
The frequency at which the vibration is perceived after intravenous oxytocin administration
Time frame: 120 minutes
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Light Touch Frequency Threshold | 693 Hz | Standard Deviation 154 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 183 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .32 score on a scale | Standard Deviation 0.15 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 184 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .59 score on a scale | Standard Deviation 0.21 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 63 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .27 score on a scale | Standard Deviation 0.15 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 185 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .86 score on a scale | Standard Deviation 0.22 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 64 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .36 score on a scale | Standard Deviation 0.16 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 31 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | 0.36 score on a scale | Standard Deviation 0.21 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 32 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .14 score on a scale | Standard Deviation 0.14 |
p-value: 0.014ANOVA
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 33 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .32 score on a scale | Standard Deviation 0.2 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 34 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .32 score on a scale | Standard Deviation 0.2 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 35 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .64 score on a scale | Standard Deviation 0.29 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 61 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .45 score on a scale | Standard Deviation 0.33 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 62 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .23 score on a scale | Standard Deviation 0.13 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 65 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .73 score on a scale | Standard Deviation 0.25 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 121 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .36 score on a scale | Standard Deviation 0.21 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 122 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .23 score on a scale | Standard Deviation 0.13 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 123 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .18 score on a scale | Standard Deviation 0.19 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 124 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .27 score on a scale | Standard Deviation 0.2 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 125 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .77 score on a scale | Standard Deviation 0.37 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 181 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .27 score on a scale | Standard Deviation 0.2 |
Secondary
Sustained Heat
0-10 verbal pain score to a 45 degree Celsius stimulus after intravenous oxytocin administration; higher score denotes worse outcome.
Time frame: 182 minutes
Population: Technical failure in one subject, leaving 10 evaluable
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Oxytocin (Pitocin®), 10 IU | Sustained Heat | .18 score on a scale | Standard Deviation 0.13 |