Effects of Chronic Musculoskeletal Pain and Opioidergic Versus Placebo Interventions on Neuroendocrine Function in Men

Use of opioid medicines for relief of chronic pain is increasing substantially but opioidergic medications and chronic pain have been both shown to perturb neuroendocrine function. The objective of this protocol is:

To determine whether long term opioid usage in men with chronic pain due to osteoarthritis results in abnormalities of Adrenocorticotropic Hormone (ACTH), cortisol, Luteinizing Hormone (LH) and testosterone secretion.

This protocol is a revised continuation of a two phase protocol with the same name which was initiated at NCCAM in 2004. In the first phase of this study 12 opioid na(SqrRoot) ve men with chronic OA pain were compared to12 healthy men by means of 12 hour overnight frequent blood sampling for measurement of baseline ACTH, cortisol, LH and testosterone. The results of phase 1 suggest that chronic osteoarthritis pain does not affect ACTH, cortisol, LH and testosterone secretion in middle aged men as compared to matched controls. In the second phase the NCCAM protocol intended to evaluate the effect of long term opioid usage AND the placebo effect if any- on the same hormones in men with chronic OA pain. Therefore the NCCAM study had a three arm design comparing MS Contin to placebo and standard treatment. When the protocol was being revised under NINR, review of the placebo literature suggested that placebo effect becomes negligible with time and therefore a two arm design was chosen comparing morphine to placebo. Baseline overnight blood hormone sampling, doses of medication, escalation and tapering schedules will be the same as in phase II of the NCCAM protocol.

Because of design changes the sample size was however recalculated to be a total of 30 opioid na(SqrRoot) ve patients with chronic OA pain. Fourteen patients, previously recruited under NCCAM, had been randomized to either morphine or placebo and finished the study. Therefore 16 additional patients need to complete the study. Taking into consideration a 25% drop out rate therefore a total of 20 patients need to be recruited. After undergoing overnight baseline hormone sampling all patients will be randomized to one of two treatment groups: MS Contin (15-90 mg), or placebo Doses of placebo and MS Contin will be escalated over 4-8 weeks in a similar fashion followed by a two-week maintenance period. At that point patients will return for repeat 12 hour frequent sampling of the same hormones as at baseline. They will then be tapered off of study medications over a period of 2-4 weeks as outpatients. Subjects will then return to clinic for a final visit and, AM blood will be obtained for ACTH, cortisol, LH, and testosterone.

The primary endpoints of this study are measures of ACTH, cortisol, LH, and testosterone secretion, whereas secondary endpoints are neurobehavioral indices such as pain symptomatology on a 0-10 (Likert) scale, the Oswestry Disability Index, Multidimensional Pain Inventory, and the Beck Depression Inventory. It is anticipated that the results of the second phase of this study will provide novel information regarding the effects of treatment with opioids on selected neuroendocrine functions in men.