What barbituates are in Tecnal-C 1/2 and how long will they remain
detctable in a urinalysis?

Tecnal C 1/2 contains 50mg Butalbital (+ 30mg codeine phosphate). 1)

The cutoff limit for barbiturate screening is 200ng/ml, for
long-acting barbiturates this allows detection of barbiturate use for
up to 72 hours post dose. 2) Butalbital has an average plasma half
life of 35 hours 3), the long acting phenobarbital has a half life
ranging from 24 to 140 hours. 2) Peak plasma concentration of 2020
ng/mL butalbital is obtained at about 1.5 hours after a 100 mg dose.
3)

If you assume a 50mg dose gives a peak plasma concentration of 1010
ng/ml, and use these data in a simple half-life calculator 4); you
find that the time needed for butalbital plasma levels to reach the
cutoff limit of 200ng/ml is 3 days and 10 hours (+ 1.5 hours), a bit
longer than quoted above. Be aware that the concentration of
butalbital may be higher in urine, these numbers relate to plasma
concentration.

1) http://www.rxmed.com/b.main/b2.pharmaceutical/b2.1.monographs/CPS-%20Monographs/CPS-%20(General%20Monographs-%20T)/TECNAL1.html
2) http://www.healthy.net/clinic/lab/labtest/002.asp
3) http://www.rxlist.com/cgi/generic/butalcod_cp.htm
4) http://www.1728.com/halflife.htm

:-) Re