Canterbury DHB
|
|
|
Drug For more information see the Clinical Pharmacology website |
Half life* |
Time to steady state* |
Ideal time for blood sample and tube colour** Sample time and tube |
amikacin
|
3 hours
|
N/A
|
Seek pharmacist advice. Green. |
amiodarone
|
8 weeks |
N/A
|
Any time. Green, red, or purple. |
amitriptyline |
15 hours (30 hours nortriptyline) |
7 days |
Just before a dose (and at least 12 hours after a dose). Trough (12 to 24 hours after last dose). Green or red. |
azathioprine (and 6 mercaptopurine) |
azathioprine 1 hour 6-TGN 5 days 6-MMP 5 days |
4 weeks |
Any time. Purple. |
carbamazepine# |
15 hours |
3 days |
Trough (12 to 24 hours after last dose). Purple. |
ciclosporin |
12 hours |
3 days |
Trough (8 to 18 hours after last dose) or peak (1.8 to 2.2 hours after last dose). Purple. |
clomipramine |
28 hours |
7 days |
Trough (12 to 24 hours after last dose). Green or red. |
clozapine |
12 hours Norclozapine: 13 hours |
3 days |
Trough (12 to 24 hours after last dose). Green or red. |
desipramine |
20 hours |
5 days |
Trough (12 to 24 hours after last dose). Green or red. |
digoxin |
36 hours |
7 days |
Trough (12 to 24 hours after last dose). Green. |
dosulepin |
22 hours |
5 days |
Trough (12 to 24 hours after last dose). Red. |
flecainide |
14 hours |
3 days |
Trough (16 to 24 hours after last dose). Green or red. |
gentamicin |
3 hours |
N/A. |
2 samples needed. First sample 30 minutes after end of infusion. For second sample, see guidelines. Record exact times on blood form. Green or red. |
itraconazole |
35 hours Hydroxitraconazole: 12 hours
|
7 days |
Trough (12 to 24 hours after last dose). Red. |
lamotrigine |
24 hours
|
5 days |
Trough (12 to 24 hours after last dose). Green or red. |
lithium |
22 hours |
5 days |
Trough (12 to 24 hours after last dose). Red. |
metformin |
5 hours |
1 day |
Trough (12 hours after last dose). Purple or red. |
methadone |
30 hours |
7 days |
Trough (12 to 24 hours after last dose). Red. |
methotrexate |
8 hours |
Not applicable |
See departmental guidelines. Red. |
mianserin |
13 hours |
3 days |
Trough (16 to 24 hours after last dose). Red. |
mycophenolate |
Mycophenolic acid 16 hours |
4 days |
Trough (8 to 18 hours after last dose). Green. |
nortriptyline |
30 hours |
7 days |
Trough (12 to 24 hours after last dose). Red. |
olanzapine |
33 hours |
7 days |
Trough (12 to 24 hours after last dose). Red. |
|
|
15 hours Hydroxyperhexiline: no data |
3 days |
Trough (12 to 24 hours after last dose). Green. |
phenobarbital# |
4 days |
3 weeks |
Trough (12 to 24 hours after last dose). Green or red. |
phenytoin#+
|
24 hours |
5 days |
Trough (12 to 24 hours after last dose). Green or red. |
tacrolimus |
10 hours |
3 days |
Trough (8 to 18 hours after last dose). Purple. |
theophylline |
8 hours |
3 days |
Trough (8 to 18 hours after last dose). Green. |
tobramycin |
3 hours |
Refer to guidelines |
2 samples needed. First sample 30 minutes after end of infusion. For second sample, see guidelines. Record exact times on blood form. Green. |
topiramate |
21 hours |
5 days |
Trough (8 to 18 hours after last dose). Red. |
valproate sodium |
12 hours |
3 days |
Trough (8 to 18 hours after last dose). Green or red. |
vancomycin |
6 hours |
Refer to dosing guidelines |
Seek pharmacist advice. Green or red. |
voriconazole# |
6 hours |
3 days |
Trough (8 to 18 hours after last dose). Green or red. |
*Time to steady state and half life are often longer in patients, e.g. frail elderly.
**Use non-gel tubes.
# Because of autoinduction, concentrations taken before 4 weeks may not reflect steady state.
+ Saturable metabolism at therapeutic doses. Careful dose-titration required.
For other drugs that Canterbury Health Laboratories measures, see Test Manager.
Topic Code: 93304
