Opiate-Induced Tolerance & Hyperalgesia in Pain Patients

Study Overview
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Brief Summary
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Opiates such as morphine are the cornerstone medications for the treatment of moderate to severe pain. Recent evidence suggests that pain patients on chronic opioid therapy become more sensitive to pain (hyperalgesia) over time. There is also a long-standing notion that analgesic tolerance to opioids (habituation) develops during chronic use even though this phenomenon has never been prospectively studied. Our specific aims propose to prospectively test the hypotheses that; 1) Pain patients on chronic opioid therapy develop dose-dependent tolerance and/or hyperalgesia to these medications over time, 2) Opioid-induced tolerance and hyperalgesia develop differently with respect to various types of pain, 3) Opioid-induced hyperalgesia occurs independently of withdrawal phenomena, and 4) Opioid-induced tolerance and hyperalgesia develop differently based on gender and/or ethnicity. This proposed study will be the first quantitative and prospective study of tolerance and hyperalgesia in pain patients and will have important implications for the rational use of opioids in the treatment of chronic pain.

Official Title
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Opiate-Induced Tolerance & Hyperalgesia in Pain Patients

Conditions
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Chronic Low Back Pain, Opioid-induced Hyperalgesia

Intervention / Treatment
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* Drug: Morphine
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: opioid naïve (or less than 4 vicodin equiv/day) 18-70 years old candidate for opioid therapy for nonmalignant pain. Exclusion Criteria: history of substance abuse or severe psychiatric disease use of medications for the treatment of neuropathic pain as these may alter tolerance or hyperalgesia neurological conditions interfering with experimental pain testing, e.g. severe peripheral neuropathy

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: 1: Placebo Pill<br>This arm contains placebo medication. | Drug: Placebo<br>* Patients will receive placebo tablets.<br>|
| Active Comparator: 2: Morphine<br>Patients will receive oral morphine therapy. | Drug: Morphine<br>* Patients will be given morphine sulfate oral medication until their back pain is adequately controlled.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pain Tolerance |  | 1 month | 
| Pain Threshold |  | 1 month | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Opioid Titration |  | 1 month | 
| Pain Intensity |  | 1 month | 
| Roland-Morris Disability Index |  | 1 month | 
| Beck Depression Inventory |  | 1 month | 
| Follow-Up Survey | Patients were asked about their average pain levels and current medication usage | 1 year |