My doctor prescribed bextra 20 mg once a day for backpain due to
arthritis. Asking him if I can take 2 pills since the pain was severe
he said "if you take 2 today don't take 2 tomorrow." In the mean time
I found out that bextra helps several hours after being taken but
later the relief wears off. I also found out that bextra's half life
is 7-10 hours, so I have started to break the pills in two and take
half a pill every 12 hours, and this seems to work better.
My questions are: 
Are bextra's 20mg tablets coated? If you don't know who manufactures bextra?
Does anybody see anything wrong in breaking the pills? I have left a
message on my doctors tape but he never called back.

If your doc says anything to the contrary, then listen to him, since
he knows your medical history, etc., but here's my version. Bextra
takes about 3 hours to reach peak concentration, 1-2 hours longer if
you take it with food. Its halflife is 8-11 hours. The pills are just
film coated, and as long as they don't taste bad, there should be no
problem with cutting the pills in half and taking them twice a day. In
fact, you are correct in that this will stabilize the concentration of
the drug in your system. However, it may lower the maximum
concentration that is reached in your body. But the steady state
concentration of the drug should be in the therapeutic range even
while taking half the dose twice a day. You can get 10 mg pills by the
way. Pharmacia, now owned by Pfizer, manufactures it.

Thank you very much purkinje-ga for your vey informative comment