Therapeutic Drug Monitoring Suggested Draw Times
For the drugs listed below, the recommended times for measuring steady state concentrations are as follows:
- For IV dosing:
Generally after loading and one maintenance dose.
- For oral therapy:
Generally after 3-5 half-lives of dosing. Sample just before next dose (trough).
Drug
|
Estimated Half-Life*
|
Draw Times
|
|
Amikacin
|
2 hrs
|
TROUGH
(30 minutes prior to next dose)
PEAK/IV
(15-30 min after dose)
|
|
Carbamazepine (Tegretol)
|
18-65 hrs
|
TROUGH
(immediately prior to next dose)
PEAK/ORAL
(3 hrs after dose)
|
|
Cyclosporine
|
10-40 hrs
|
TROUGH
(immediately prior to next dose)
|
| Digoxin (Lanoxin) |
37 hrs
|
TROUGH
(immediately prior to next dose)
PEAK/ORAL
(6-8 hrs after dose)
PEAK/IV
(4 hrs after dose)
|
|
Gentamicin
|
1-2 hrs
|
TROUGH
(immediately prior to next dose)
PEAK/ORAL
(60 min after IM injection)
PEAK/IV
(30-60 min after dose)
|
|
Lidocaine
|
44-107 min
|
STEADY STATE (TROUGH):
12 hrs after initial dose Every 24 hrs thereafter OR every 12 hrs if hepatic insufficiency exists.
|
|
Lithium
|
40-58 hrs
|
PEAK
(6-12 hrs after dose)
|
|
Phenobarbital (Luminal)
|
4 days
|
TROUGH
(immediately prior to next dose)
PEAK/ORAL
(3-9 hrs after dose)
PEAK/IV
(2-4 hrs after dose)
|
|
Phenytoin (Dilantin)
|
18-22 hrs
|
TROUGH
(immediately prior to next dose)
PEAK/ORAL
(3-9 hrs after dose)
PEAK/IV
(2-4 hrs after dose)
|
|
Primidone(Mysoline)
|
8-15 hrs
|
TROUGH
(immediately prior to next dose)
|
|
Procainamide
|
3-6 hrs
|
TROUGH
(immediately prior to next dose)
PEAK/ORAL
(75 min after dose)
PEAK/IV
(immediately after dose)
|
|
Quinidine
|
5-12 hrs
|
TROUGH
(immediately prior to next dose)
Repeat 1-2 days after change in dose.
|
|
Tacrolimus
|
8-16 hrs
|
TROUGH
(immediately prior to next dose)
|
|
Theophylline
(Aminophylline)
|
4-7 hrs
|
TROUGH
(immediately prior to next dose)
PEAK/ORAL
(2-4 hrs after dose)
PEAK/IV
(30 min after dose)
|
|
Tobramycin
|
2-3 hrs
|
TROUGH
(immediately prior to next dose)
PEAK/IV
(30 min after dose)
|
|
Valproate, Depakene
|
9 hrs
|
TROUGH
(immediately prior to next dose)
PEAK/ORAL
(1-3 hrs after dose)
|
|
Vancomycin
|
4-6 hrs
|
TROUGH
(immediately prior to next dose)
PEAK/IV
(30 min - 2 hrs after dose)
|
|
|
|
|
* Estimated half-lives are for normal adults with normal renal and liver function.
Source: Li, Dai, PhD, and Nichols, James, PhD, DABCC. Specimen Collection and Stability for Therapeutic Drug Monitoring. Therapeutic Drug Monitoring and Toxicology, Vol.18, No. 1, Jan. 1997. Published by the Education Department of the American Association for Clinical Chemistry, Inc.
If Toxicity is Suspected
For suspected toxicity, samples may be drawn at any time. Draw times should be indicated on sample tube. You also may consult the New Mexico Poison Center at 1-800-222-1222.
For More Information
To obtain draw times for drugs not listed here, call the New Mexico Poison Center at 1-800-222-1222.
For more information, contact Client Services at
505-938-8922 or
800-245-3296.