Table 3

Inhibition constant (Ki) for select barbiturates andR(+)- or S(−)-enantiomers determined by inhibition of [3H]TCP binding to its high-affinity site on the desensitized nAChR

BarbiturateKi
μM
Amobarbital1017  ± 58
Amylbarbital872  ± 35
Pentobarbital
 Racemic338  ± 28
R(+)233  ± 11
S(−)396  ± 15
Isobarbital
 Racemic
R(+)582  ± 28
S(−)320  ± 43

The Ki values (averaged) were calculated using the Cheng-Prusoff relationship (eq. 2) and the IC50 values obtained from Fig. 6.