| Laboratory: | Clinical Biochemistry | ||||
| Test Name: |
RIFAMPIN - (P) or (S)
Test Code:
RIFA
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| Clinical Information: |
Test detects Rifampin (Synonyms: Rifadin®; Rifampicin®) and 25-desacetylrifampin. Test referred to NMS Labs for analysis by High Performance Liquid Chromatography/Tandem Mass Spectrometry (LC-MS/MS).
There is no consensus on the utility of measuring serum/plasma rifampin levels. Analysis of serum/plasma rifampin levels should be isolated to cases where: • response to therapy is slower than expected • when malabsorption may be suspect • drug resistant tuberculosis is present • hepatic dysfunction is playing a role in treatment failure In order to ascertain delayed absorption versus malabsorption, drug levels following oral dosing should be obtained at 2 hours and 4-6 hours after dose. There is no consensus on relationship between peak plasma/serum rifampin levels and outcomes. However, a dose increase is recommended if peak level is less than 6 μg/mL. Peak level: A fasting sample should be collected 2 hours post dose following oral dosing or 45 minutes following IV infusion Trough levels: Not recommended Peak plasma concentrations averaged 16 ± 11 mcg/mL (range 5 to 27 mcg/mL) following 6 weeks of daily administration of 600 mg oral rifampin. |
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| Collection Devices: |
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| Specimen Required: |
Plasma: 1.0 mL
Pediatric Plasma: 0.4 mL
Serum or plasma (EDTA), collected without gel. Peak levels: A fasting sample should be collected 2 hours post dose following oral dosing or 45 minutes following IV infusion. Trough levels: Not recommended |
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| Referral: |
Promptly centrifuge and separate serum or plasma into an amber plastic screw capped vial using approved guidelines. Store & ship plasma or serum (collected without gel) frozen at -20°C in an amber vial to protect from light.
Stability: Frozen -20°C: 5 months (not stable at room temperature or refrigerated). |
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| Requisition: | |||||
| Reference Values: |
• Peak plasma concentrations averaged 16 ± 11 mcg/mL (range 5 to 27 mcg/mL) following 6 weeks of daily administration of 600 mg oral rifampin.
• Comparable peak plasma concentration achieved with single 600 mg intravenous administration of rifampin. • Plasma concentrations 8 hours after a single intravenous administration of 600 mg rifampin averaged 5.8 ± 3.3 mcg/mL on day one and 2.6 ± 1.9 mcg/mL on day seven. • Time to maximum concentration is significantly delayed and reduced for oral dosing given after the ingestion of food. Source: Rifampin PI, Sanofi-Aventis, 2013; Ruslami, R, et al., Antimicro Agents Chemother 51(7):2546, 2007. Reporting limit: > 0.25 mcg/mL |
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| Availability: |
Within 2 Weeks
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| See Also: | |||||
| More Information: |
Rejection criteria: received at room temperature, refrigerated temperature or plasma/serum collected using polymer gel separation tube (PST or SST). Store and ship frozen to NMS Labs http://www.nmslabs.com/tests/Rifampin--Serum-Plasma/4110SP
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