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Sinemet CR is a slow release version of  regular Sinemet.  The rate of
bioavailability of levodopa is much slower than regular Sinemet.  It takes as
much as an hour longer to reach peak plasma levels using the CR version.  One
of the other problems is that carbidopa (the small number in 25/100) releases
even slower than the levodopa.  This means that levodopa is entering your
system with insufficient carbidopa.  Carbidopa is provided with Sinemet to
inhibit nausa, vomiting, etc.  I have been told that the bioavailability of
carbidiopa in CR is around 54%.

There are two solutions to the problems of nausa in the morning.  (1) Pick up
a bottle of Nodosyn from your doctor.  Nodosyn is free and is not sold in
drug stores.  This tablet is a 25 mg tablet of carbidopa.  Take this with
your first CR in the morning and you should be OK.  (2)  If the time taken
from the swallowing of the first CR until you feel better is too long, it is
suggested that rather than use a Nodosyn, a regular Sinemet 25/100 either
half or whole be used.  You may want to delay the taking of the CR due to the
regular tablet.

In a sturdy printed in NEUROLOGY, 1996, pp 1059-1061, called Early Morning
Akinesia in Parkinson's Diserase: Effect of standard carbiopa/levodopa and
sustained-release carbidopa/levodopa the times to peak plasma level was
studied.  The time of onset of clincial benefit was significantly earlier
with the regular Sinemet ( 47 min to 75 min ) as the first dose than using
sustained release (76 min to 106 minutes) as the first dose.  To reach peak
plasma levels was also very interesting.   Regular averaged 36 minutes at a
peak level of 1601 ug/ml and sustained resease averaged 111 minutes at a peak
of 1260 ug/ml.  This yields a 78% peak plasma level of sustained release vs
regular Sinemet.

I hope this gives you some ideas to discuss iwth your doctor on how you might
change the medication.

Regards,
Alan Bonander