Drug

Residual concentration at time of sampling (ng/mL) Ct

Mean half-life (h) t1/2

Elimination constant k = log(2)/t1/2

Initial concentration 48 h prior to sampling (ng/mL) C0 = Ct/ekt

Blood concentration from database (ng/mL)

Lormetazepam

6.8

10 [16]

0.693/10

= 0.0693

6.8/e−(0.0693)48

6.8/0.036

= 189

Therapeutic: 2 - 10 [12]

Toxic: 100 [12]

Lorazepam

6.3

14 [17]

0.693/14

= 0.0495

6.3/e−(0.0495)48

6.3/0.093

= 68

Therapeutic: 20 - 250 [12]

Toxic: 300 - 500 [12]

Nordiazepam

16.2

65 [11]

0.693/65

= 0.0106

16.2/e(0.0106)48

16.2/0.6

= 27

Therapeutic: 200 - 800 [12]

Toxic: 1500 - 2000 [12]

Oxazepam

Assumed to be 1.0 (limit of quantification)

8 [13]

0.693/8

= 0.0866

1.0/e(0.0866)48

1.0/0.0156

= 64

Therapeutic: 200 - 1500 [12]

Toxic: 2000 [12]