Version June 2024
| Drug name | Timing for collection of serum concentration | Target peak concentration | Time for additional sampling to assess for delayed absorption or malabsorption of orally administered drug* |
| Amikacin | Intramuscular: 2 and 6 hours Intravenous: 2 and 6 hours after completion of a 30 to 60 minute infusion¶ | Target for calculated peak concentration:¶
| Not applicable |
| CapreomycinΔ | Intramuscular: 2 and 6 hours Intravenous: 2 and 6 hours after completion of a 30 to 60 minute infusion¶ | Target for calculated peak concentration:¶
| Not applicable |
| Clofazimine | Oral: 2 to 3 hours (fasting), 4 to 8 hours (when given with food) | 0.5 to 2 mcg/mL | 6 to 7 hours (fasting only) |
| Cycloserine | Oral: 2 hours | 20 to 35 mcg/mL◊ | 6 hours |
| Ethambutol | Oral: 2 to 3 hours | 2 to 6 mcg/mL (for 15 to 25 mg/kg daily dose) 4 to 12 mcg/mL (for 50 mg/kg thrice or twice weekly dose) | 6 to 7 hours Delayed or erratic absorption occurs frequently |
| Ethionamide | Oral: 2 hours | 1 to 5 mcg/mL | 6 hours Delayed or erratic absorption occurs frequently |
| Isoniazid | Oral: 2 hours (fasting); some also check 6-hour levels | 3 to 5 mcg/mL (for 5 mg/kg up to 300 mg daily dose) 9 to 15 mcg/mL (for 15 to 25 mg/kg twice weekly dose) | 6 hours |
| Kanamycin | Intramuscular: 2 and 6 hours Intravenous: 2 and 6 hours after completion of a 30 to 60 minute infusion¶ | Target for calculated peak concentration:¶
| Not applicable |
| Levofloxacin | Oral: 2 hours | 8 to 12 mcg/mL | 6 hours |
| Linezolid | Oral: 2 hours Intravenous: 30 minutes after completion of infusion | 12 to 24 mcg/mL | Not generally performed |
| Moxifloxacin | Oral: 2 hours* | 3 to 5 mcg/mL | 6 hours |
| Para-aminosalicylic acid | Oral: 6 hours (enteric-coated sustained release PASER formulation) | 20 to 60 mcg/mL | Not applicable |
| Pyrazinamide§ | Oral: 2 hours | 20 to 40 mcg/mL (for 25 mg/kg daily dose) 60 to 80 mcg/mL (for 50 mg/kg thrice or twice weekly dose) | 6 hours |
| Rifabutin¥ | Oral: 3 hours | 0.45 to 0.9 mcg/mL | 7 hours |
| Rifampin (rifampicin) | Oral: 2 hours | 8 to 24 mcg/mL | 6 hours We routinely perform 6-hour levels in all patients receiving rifampin to assess for delayed absorption or malabsorption* |
| Streptomycin | Intramuscular: 2 and 6 hours Intravenous: 2 and 6 hours after completion of a 30 to 60 minute infusion¶ | Target for calculated peak concentration:¶
| Not applicable |
* To assess for delayed or malabsorption, a second sample should be collected approximately 6 to 7 hours after an oral dose (depending on the drug as noted above). This is particularly important for patients with a history of diabetes mellitus, gastrointestinal disorders, HIV, cystic fibrosis, or alcohol abuse and in all patients receiving ethambutol or ethionamide. In delayed absorption, the 6- or 7-hour concentration is similar to or higher than 2-hour values. If both values are beneath the expected peak, malabsorption should be suspected.
¶ Serum concentrations of aminoglycosides (amikacin, streptomycin, kanamycin) and capreomycin obtained less than 2 hours after an intramuscular dose or completion of an intravenous infusion may be falsely elevated due to incomplete distribution of drug to body tissues. To avoid misinterpretation, two post-distribution concentrations should be drawn and the peak concentration determined by pharmacokinetic calculation using linear regression to 1 hour post-intramuscular dose or end of intravenous infusion. These calculations are usually performed by pharmacists skilled in aminoglycoside clinical pharmacokinetics. Trough concentrations (target <5 mcg/mL to undetectable) may also be evaluated to confirm drug clearance following a 24-hour dose. Refer to the UpToDate topic review of aminoglycosides dosing and administration for detail.
Δ Capreomycin is not available in the United States; availability in other countries is limited.
◊ Central nervous system toxicity is associated with cycloserine concentrations >35 mcg/mL but may occur at even lower concentrations. Some experts prefer to maintain the concentration <30 mcg/mL.
§ An elevated uric acid is an expected additional finding in patients on pyrazinamide. If not present, it may indicate that the patient is not taking the drug or there is malabsorption.
¥ Rifabutin is absorbed more slowly than most other oral agents. On the day of sampling only, rifabutin can be given 1 hour before the other drugs, so that rifabutin sample times match the 2- and 6-hour times for other drugs. This limits the collection to two venipunctures.آیا می خواهید مدیلیب را به صفحه اصلی خود اضافه کنید؟
