Pain
Conditions
Keywords
pain, chronic pain, acetylcholine, clonidine, a2-adrenergic agonists, alpha2-adrenergic agonists
Brief summary
The purpose of this study is to compare the amount of acetylcholine release after a single injection of clonidine in normal volunteers and individuals with neuropathic pain.
Detailed description
This study is part of a pain center grant that focuses on how pain, especially chronic neuropathic pain, alters the response to traditional and non-traditional analgesics (pain medications). The way that nerve fibers carry pain information to the brain is thought to change after surgery and in cases of chronic pain. For this reason, some medicines work better to relieve pain in healthy people who have a sudden painful injury when compared to people after surgery or to people with chronic pain. Currently available pain medications may not relieve all types of pain or may relieve pain only at doses that produce side effects and potential complications. The aim of this study is to understand the mechanisms by which intrathecal clonidine (or clonidine injected into cerebrospinal fluid) increases in potency and efficacy by examining the cerebrospinal fluid of healthy individuals, before and after clonidine administration, as well as looking at the spinal fluid of people with chronic neuropathic nerve pain. More specifically, in this study, researchers will compare acetylcholine release (a protein-like substance found in cerebrospinal fluid) in normal volunteers and patients with neuropathic pain after a single injection of clonidine. After baseline measurements, including blood pressure and heart rate, participants will be trained to accurately estimate pain by way of thermal heat testing. Next a small amount of spinal fluid will be withdrawn from each participant to measure the amounts of naturally-made chemicals in the participants' cerebrospinal fluid. Participants then will receive an injection of clonidine. After the injection, additional samples of spinal fluid will be taken to measure chemical changes in the fluid. Duration of the study for participants is 1 day, and includes 1 visit to the research center, lasting approximately 3 hours.
Interventions
DRUGclonidine
Patients will receive intrathecal clonidine (or clonidine injected into cerebrospinal fluid)
Sponsors
National Institute of Neurological Disorders and Stroke (NINDS)
Wake Forest University Health Sciences
Study design
Allocation
RANDOMIZED
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
* Healthy adult volunteers * Patients with neuropathic pain
Exclusion criteria
* Pregnancy * Allergy to clonidine * Currently taking clonidine or other direct a2-adrenergic agonists * Taking cholinesterase inhibitors
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Acetylcholine Concentration in Cerebrospinal Fluid | 60 minutes | Acetylcholine levels in CSF after administration of intrathecal clonidine measured by High-performance liquid chromatography (HPLC). |
Countries
United States
Participant flow
Recruitment details
Subjects were recruited from 9/1/2004-6/2/2006. Subjects were recruited from a pain clinic and the control group were healthy subjects.
Pre-assignment details
No significant events or abnormal approaches noted.
Participants by arm
| Arm | Count |
|---|---|
| Neuropathic Pain Subjects Subjects with existing neuropathic pain Outcome criterion is acetylcholine concentration in cerebrospinal fluid (CSF) at 60 minutes after injection. | 24 |
| Healthy Subjects Healthy subjects with no existing pain conditions. Outcome criterion is acetylcholine concentration in cerebrospinal fluid (CSF) at 60 minutes after injection. | 19 |
| Total | 43 |
Baseline characteristics
| Characteristic | Neuropathic Pain Subjects | Healthy Subjects | Total |
|---|---|---|---|
| Age, Categorical <=18 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical >=65 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical Between 18 and 65 years | 24 Participants | 19 Participants | 43 Participants |
| Age, Continuous | 47.875 years STANDARD_DEVIATION 11.48 | 32 years STANDARD_DEVIATION 8.51 | 40.86 years STANDARD_DEVIATION 12.91 |
| Sex: Female, Male Female | 18 Participants | 13 Participants | 31 Participants |
| Sex: Female, Male Male | 6 Participants | 6 Participants | 12 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 0 / 24 | 0 / 19 |
| serious Total, serious adverse events | 0 / 24 | 0 / 19 |
Outcome results
Primary
Acetylcholine Concentration in Cerebrospinal Fluid
Acetylcholine levels in CSF after administration of intrathecal clonidine measured by High-performance liquid chromatography (HPLC).
Time frame: 60 minutes
Population: There was no difference noted in acetylcholine levels in healthy subjects compared to subjects with chronic pain
| Arm | Measure | Value (MEAN) |
|---|---|---|
| Neuropathic Pain Subjects | Acetylcholine Concentration in Cerebrospinal Fluid | 406 picograms per milliliter (pg/ml) |
| Healthy Subjects | Acetylcholine Concentration in Cerebrospinal Fluid | 383 picograms per milliliter (pg/ml) |