Re :   Carla D'Anna's question on chlorzoxazone(Parafon Forte)

        Chlorzoxazone is one of those produces we seem to know very little
about,  probably because many think it is of questionable  efficacy.  It is
apparently a centrally acting muscle relaxant,  but we're not sure how it
works at all.  The skeletal muscle relaxant effects are "minimal and are
probably related to its sedative effect".  Plasma concentrations required
for skeletal muscle relaxation are not known.  The half-life of the active
component is 66 minutes.  In addition,  more than 40 cases of hepatotoxicity
have been reported to date associated with this product(and occur 1-5 months
post-dose).   Dosages listed for children are 20mg/kg/day,  or 125-500 mg
3-4 times daily.   No protein binding estimates have been reported.  The
pKa is 8.2 which could lead to some ion trapping in milk,  but we have
absolutely no estimates of the concentrations in milk.

        There are not a lot of good muscle relaxants.  Actually the
enzodiazepines (Valium, Lorazepam, etc) are probably  much better at
relaxing skeletal muscles than the above product.   I don't mind using drugs
that really do something,  but some of these products really irritate me.
I'm sorry I can't  give you any good info on this product,  there's simple
none available.

tom hale