Appeal No. 2002-0783 Page 6
Application No. 09/268,957
reportedly increased the erectogenic efficacy of sildenafil (specification, page 3, lines
21-23). However, the oral administration of sildenafil is also accompanied by dose-
responsive undesirable side effects. Consequently, at doses higher than 50 milligrams,
the incidence of such side effects as abnormal vision problems ranging from blue or
green halo effects to blurring, dyspepsia, nasal congestion, blinding headaches,
flushing redness, diarrhea, dizziness, rash, and urinary tract infection increases (id.,
lines 23-31). Other more serious side effects have also been reported (specification,
paragraph bridging pages 3 and 4). Thus, at the time the invention was made, there
was a need and desire for oral administration forms that promote the bioavailability of
sildenafil at lower doses while minimizing side effects (specification, page 4, lines 9-11).
Bell '534, Bell '901, and Bell '283 disclose that sildenafil and a suitable
pharmaceutically acceptable vehicle or carrier may be prepared for sublingual
administration. We are persuaded that a person having ordinary skill, armed with the
disclosure of the Bell patents and the acknowledged state of the prior art described in
applicant's specification, would have found it obvious to apply the teachings of El-
Rashidy to the water soluble drug sildenafil. In this manner, a person having ordinary
skill would have arrived at a composition providing a controlled release of sildenafil by
sublingual route containing (1) from 25 to 100 milligrams of sildenafil; (2) an osmotic
agent; (3) a swellable hydrophilic carrier; and (4) a water dispersible polymer. As
disclosed by El-Rashidy, that composition would have a T90 value in the range of more
than about 25 to about 300 and a ratio of the amount by weight percent of the osmotic
agent to the amount by weight percent of the swellable hydrophilic carrier less than
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