Appeal No. 2003-1743 Page 2
Application No. 09/540,205
Applicants state that, to the best of their knowledge, other researchers have not
recognized that pain may be treated with methadone by varying the proportions of the
two isomers (id., page 3, lines 5 through 8). Further according to applicants, “[t]he
racemic mixture of methadone does not provide an efficient and effective treatment for
pain having both neuropathic and somatic components. The only available adjustment
when using d,l-methadone is an increase of the dose” (id., page 4, lines 1 through 4).
As stated in the specification, page 4, lines 11 through 20:
The present invention is based on the discovery that the d-isomer of
methadone is effective in treating neuropathic pain while the l-isomer of
methadone is the only effective isomer of methadone for treating somatic
pain. Thus, a ‘cocktail’ of different amounts of the d- and l- isomers of
methadone tailored to the individual patient is best for treating such pain.
The present invention provides a more effective composition and
method of treating pain having both neuropathic and somatic components.
This is accomplished by using non-racemic mixtures of varying amounts of
d-methadone and l-methadone.
Another aspect of the invention is based on applicants’ observation that adding
an opioid antagonist, e.g., naloxone or naltrexone, to a non-racemic methadone mixture
or to racemic dl-methadone or l-methadone eliminates mu-receptor activity. Such
compositions can be used for treating pure neuropathic pain (id., page 5, lines 6 through
16). Stated another way, “[i]n yet another aspect of the present invention, naloxone
naltrexone [sic], or the like, is administered in an effective amount to eliminate mu-
receptor activity with the non-racemic methadone mixture of the present invention or
with racemic dl-methadone or l-methadone” (id., page 6, lines 3 through 7).
Claims 1, 2, 10, and 22, which are illustrative of the subject matter on appeal,
read as follows:
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Last modified: November 3, 2007