Test Background Tacrolimus is a macrolide antibiotic derived from the fungus Streptomyces tsukubaensis. Like ciclosporin, tacrolimus inhibits calcineurin to suppress T cells. Tacrolimus is metabolised by CYP3A4, thus its concentrations are affected by drugs that inhibit (calcium channel blockers, antifungal agents, some antibiotics, grapefruit juice) or induce (anticonvulsants, rifampin) this enzyme. Tacrolimus has a narrow therapeutic range, and adverse effects are common, particularly at high dose and concentrations, making therapeutic drug monitoring essential.
Clinical Indications Therapeutic drug monitoring, particularly in individuals co-administered CYP3A4 substrates, inhibitors, or inducers Adjusting dose to optimise immunosuppression while minimising toxicity
Reference Range See report
Sample Required EDTA (lavender top) or heparin (green top)
Sample Volume 2 mL (Timed see below)
Turnaround Time Within 24h from receipt of sample into the Leslie Brent Laboratory but sameday weekday only service if specimen is received by 13:30pm
The sample should be taken just before the subsequent dose (trough level) and at a constant interval; 12h for Tacrolimus (Prograf/Adoport), or 24h for Tacrolimus (Advagraf)
Tests performed Monday-Friday Only
Not currently performed in house; this is a referred test. Please send specimens directly to the Leslie Brent Laboratory, West London Renal and Transplant Centre, Hammersmith Hospital 020 331 36637 Clinical Biochemistry will forward any specimens received to the Leslie Brent Laboratory.