Recruitment did not accrue as expected.

This proposal is to conduct a double-blinded, randomized, placebo-controlled, crossover clinical study to examine the hypothesis that ramelteon would reduce pain score and improve functional status in subjects with neuropathic pain.

Neuropathic pain is a chronic pain condition resulting from injury to the peripheral and/or central nervous system. Despite extensive research over the last several decades, neuropathic pain remains poorly managed due to the lack of effective pharmacological tools. To date, little has been known regarding the effect of melatonin and its analogues on clinical neuropathic pain. We propose to conduct a randomized, placebo-controlled, double-blinded, and crossover clinical trial to examine the effect of ramelteon [a melatonin (MT) 1/ MT2 receptor agonist] on neuropathic pain. We hypothesize that ramelteon would reduce pain score and improve functional status in subjects with neuropathic pain.

Inclusion Criteria:

1. Subject will be between ages 18 to 65 years.
2. Subject has not been on ramelteon for at least one month.
3. Subject agrees to make no change in his/her current pain medications during the entire study period (5 weeks). This requirement will ensure that valid comparisons of primary and secondary measures can be made before and after the study.
4. Subject has a VAS pain score of 5 or above at the beginning of the study.
5. Subject has had a neuropathic pain condition as listed above for at least three months. This requirement is to avoid clinical uncertainty from an unstable pain condition and to minimize the study variation.
6. Female subjects of childbearing potential must have a negative urine pregnancy test at the initial visit.

Exclusion Criteria:

1. Subject has moderate to severe liver impairment.
2. Subject has Liver Function Tests (LFT's) >1.5X normal.
3. Subject has a history of renal impairment.
4. Subject has moderate or severe cardiac or pulmonary disease including a base line oxygen saturation of less than 95% on room air or any requirement for supplemental oxygen.
5. Subject has a history of glaucoma.
6. Subject has obstructive sleep apnea.
7. Subject is taking medications for sleep disorders including insomnia.
8. Subject has a major psychiatric disorder (major depression requiring a recent hospitalization within three months prior to the study; bipolar disorder; schizophrenia; psychotic disorders; substance abuse).
9. Subject has a history of dementia or delirium.
10. Subject has a history of falls.
11. Subject is pregnant or lactating.
12. Subject is using an illicit drug detected by a screening test.
13. Subject is currently taking Fluvoxamine.
14. Subject has been taking Ketoconazole in the past two weeks.
15. Subject has known hypersensitivity to ramelteon.
16. Subject has pending litigation related to his/her neuropathic pain condition.
17. Subject has Concurrent participation in other research drug trials or other study participation within 30 days of enrollment in this study.

Two weeks for each intervention and a 1 week period of no intervention in between phases.

Problems with recruitment and termination of the study consequently resulted in uninterpretable data.