Pharamaceutical compositions for treating chronic pain and pain associated with neuropathy

Abstract

The present invention provides methods and compositions for the treatment of neuropathic pain. In certain embodiments, compositions comprising an dextromethorphan (or other N-methyl-D-aspartate receptor antagonist), tramadol, and gabapentin can synergistically act to reduce pain in a human patient. Pharmaceutical compositions may also comprise a capsaicinoid, an esterified capsaicinoid, and / or a tricyclic antidepressant.

Description

[0001]This application claims priority to U.S. Application No. 60 / 954,251 filed on Aug. 6, 2007, the entire disclosure of which is specifically incorporated herein by reference in its entirety without disclaimer.BACKGROUND OF THE INVENTION[0002]Chronic pain is a common problem that presents a major challenge to healthcare providers because of its complex natural history, unclear etiology, and poor response to therapy. Chronic pain is a poorly defined condition, and opinions vary regarding which duration qualifies a pain as chronic. Most clinicians consider ongoing pain lasting longer than 6 months as diagnostic, and others have used 3 months as the minimum criterion. In chronic pain, the duration parameter is used arbitrarily; some authors suggest that any pain that persists longer than the reasonable expected healing time for the involved tissues should be considered chronic pain. The pathophysiology of chronic pain is multifactorial and complex and still is poorly understood. Some...

AI Technical Summary

Benefits of technology

[0008]The present invention overcomes limitations in the prior art by providing improved methods and compositions for the treatment of pain. As described below, the inventor has discovered that the combination of low dosages of an NMDA antagonist (e.g., dextromethorphan), the atypical opioid tramadol, and gabepentin demonstrate a clear synergy and can eliminate the majority of pain in patients with neuropathic pain who are refractory to traditional therapies. In certain embodiments, gabapentin may be substituted with a gabapentin analog such as pregabalin, and tramadol may be substituted with a tramadol analog. As shown in the below examples, these pharmaceutical compositions resulted in pain reduction with little or no toxicity and / or harmful side effects. Without wishing to be bound by any theory, it is believed that the low doses of the active agents used was responsible for the observed reduction or elimination of harmful side effects, as compared to traditional pain therapies. These present invention may be used to treat pain associated with, e.g., fibromyalgia syndrome, diabetic neuropathy, multiple scelerosis and / or cancer.

Problems solved by technology

Chronic pain is a common problem that presents a major challenge to healthcare providers because of its complex natural history, unclear etiology, and poor response to therapy.

The pathophysiology of chronic pain is multifactorial and complex and still is poorly understood.

Unfortunately, several adverse side effects are associated with the drugs provided at the above dosages.

All opiates have side effects, of which the most dangerous are respiratory and cardiovascular depression associated with excessive sedation.

NSAIDs may also induce side effects such as exacerbation of bleeding tendencies and the impairment renal function.

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