• Area under the curve of present pain intensity with ambulation at each cued time point [ Time Frame: Every 30 seconds for a maximum of 15 minutes ] [ Designated as safety issue: Yes ]
• Walking tolerance as measured by time and distance walked on the treadmill walking test [ Time Frame: 1.5 hours ] [ Designated as safety issue: Yes ]
• BPI Interference Measure [ Time Frame: 0 ] [ Designated as safety issue: No ]
• Time to return to baseline pain level after the treadmill ambulation assessment (Trecovery) [ Time Frame: 15 minutes ] [ Designated as safety issue: No ]
• Adverse events (decrease in respiratory rate, sedation, constipation, low blood, nausea and vomiting, or itching graded on a 0-3 scale (0:none, 1:mild, 2:moderate, 3:severe.) [ Time Frame: 6 Months - 1 year ] [ Designated as safety issue: Yes ]
• Patient Global Impression of Change [ Time Frame: 0 ] [ Designated as safety issue: No ]
• Oswestry Disability Index score, Swiss Spinal Stenosis score, Patient Global Impression of Change, and Roland Morris Disability Questionnaire. [ Time Frame: 15 min ] [ Designated as safety issue: No ]

The primary objective of the proposed pilot study is to determine the efficacy of oxymorphone hydrochloride and propoxyphene/acetaminophen combination in prolonging the time to onset of pain and reducing the severity of pain associated with walking in patients with neurogenic intermittent claudication. The secondary objective is to examine the functional benefit of oxymorphone hydrochloride and propoxyphene/acetaminophen combination with respect to improvement in duration and distance of walking tolerance.

The proposed study will also provide the foundation for a treadmill-based methodology for assessing the analgesic efficacy of drugs for low back pain provoked by standing and walking associated with lumbar spinal stenosis.

• Drug: Placebo
• Drug: Propoxyphene/acetaminophen
• Drug: oxymorphone hydrochloride

• Placebo Comparator: Placebo
• Active Comparator: Darvocet & Opana

• Simon LS, Evans C, Katz N, Bombardier C, West C, Robbins J, Copley-Merriman C, Markman J, Coombs JH. Preliminary development of a responder index for chronic low back pain. J Rheumatol. 2007 Jun;34(6):1386-91.
• Markman JD, Dworkin RH. Ion channel targets and treatment efficacy in neuropathic pain. J Pain. 2006 Jan;7(1 Suppl 1):S38-47. Review.
• Deen HG Jr, Zimmerman RS, Lyons MK, McPhee MC, Verheijde JL, Lemens SM. Test-retest reproducibility of the exercise treadmill examination in lumbar spinal stenosis. Mayo Clin Proc. 2000 Oct;75(10):1002-7.
• Deen HG, Zimmerman RS, Lyons MK, McPhee MC, Verheijde JL, Lemens SM. Use of the exercise treadmill to measure baseline functional status and surgical outcome in patients with severe lumbar spinal stenosis. Spine. 1998 Jan 15;23(2):244-8.
• Stucki G, Daltroy L, Liang MH, Lipson SJ, Fossel AH, Katz JN. Measurement properties of a self-administered outcome measure in lumbar spinal stenosis. Spine. 1996 Apr 1;21(7):796-803.

Inclusion Criteria:

• Patients must present with clinical symptoms of neurogenic claudication (exercise induced leg pain, numbness, heaviness, or vague discomfort in part or all of one or both legs provoked with walking and standing and relieved by sitting, squatting, or forward flexion posturing) and endorse limitation of walking tolerance due to these symptoms
• Leg/low back pain ratio must be greater than 50:50
• Numeric Rating Scale (NRS) for pain ≥ 6 in response to the following question: "Circle one number (from 0=no pain to 10=worst pain) - How would you rate the worst leg and lower back pain you experienced during walking last week?"
• Patients must have confirmatory imaging by MRI or CT scan demonstrating at least one level of lumbar spinal stenosis within 1 year
• Duration of symptoms > 3 months
• Age > 50 years; male or female

Exclusion Criteria:

• Past or present existence of a movement disorder, e.g., Parkinsonism, or an neurologic disease that might affect the ability to ambulate (e.g., signs/symptoms of cauda equina compression)
• Cognitive impairment preventing full understanding or participation in the study
• Peripheral vascular disease
• Moderate to severe arthritis of the knee or hip that might severely compromise ambulation
• Past or present lower extremity peripheral vascular disease
• Serious concomitant medical illness (e.g., heart disease) that might impair ambulation assessment
• Previous lumbar surgery for spinal stenosis (laminectomy with or without fusion) within the past 2 years or epidural steroid injection in the preceding 4 months.
• Severe psychiatric disorder
• Mean time to severe symptoms > 15 minutes.
• Epidural steroid treatment within the last three months
• History of drug or alcohol dependence
• Serious intercurrent illness
• Hypersensitivity to oxymorphone hydrochloride
• Hypersensitivity to propoxyphene or acetaminophen
• Severe bronchial asthma or hypercarbia, morphine analogs such as codeine, or any of the other ingredients of Opana
• Suspicion of paralytic ileus
• Moderate or severe hepatic impairment
• Major conduction abnormality on ECG or cardiac (Bruce protocol) stress test within the past year.
• Ongoing treatment with a long-acting opioid or regularly-scheduled use of a short acting opioid (>3 doses/day on four or more days/week).