- Enter the recipient's weight (kg). The weight-based starting-dose estimate updates automatically.
- Choose the formulation — immediate-release (IR, twice-daily), extended-release once-daily (Advagraf / Astagraf XL), or Envarsus XR — to see the per-day and per-dose range and the practical-capsule guidance.
- Choose the time after transplant to look up the typical target whole-blood trough range for that period.
- Treat all outputs as protocol-dependent starting estimates. The actual dose is titrated to measured 12-hour troughs, and your transplant center's protocol governs both the starting dose and the target range.
All computation runs in your browser; no values are stored or transmitted.
When to Use
Use this reference when you need a weight-based starting estimate for tacrolimus in a de novo kidney-transplant recipient, or a quick lookup of the typical target whole-blood trough for the relevant time after transplant. It is meant as an educational cross-check against a transplant center's written immunosuppression protocol — never as a substitute for it. Once therapy starts, dosing is driven by measured 12-hour troughs, not by the weight-based formula.
Appropriate use
Estimating an initial tacrolimus dose at the time of a kidney transplant, planning a formulation choice (immediate-release vs. extended-release vs. Envarsus XR), and confirming the broad target-trough band expected for the early, intermediate, or maintenance period. Useful for trainees, transplant nurses, and clinicians orienting to a center's tacrolimus protocol.
When NOT to rely on it
Do not use these numbers as fixed targets. Target troughs and starting doses are highly center- and protocol-specific and depend on immunologic risk, concomitant immunosuppression (steroids, mycophenolate, belatacept), rejection history, assay, ethnicity/CYP3A5 genotype, drug interactions, and graft function. The formulations are not mg-for-mg interchangeable — recheck troughs after any switch. This tool does not account for pediatric dosing, liver/heart/lung transplant, dialysis, or hepatic impairment.
Pearls & Pitfalls
The trough drives the dose
Tacrolimus has a narrow therapeutic index and wide interindividual pharmacokinetics, so the weight-based starting dose is only a starting point — once therapy begins, dosing is titrated to 12-hour whole-blood trough (C₀) concentrations. Targets are generally highest early after transplant and stepped down over the first year as immunologic risk falls, to limit cumulative calcineurin-inhibitor nephrotoxicity.
Drug & food interactions move levels a lot
Tacrolimus is a CYP3A4/3A5 and P-glycoprotein substrate. Azole antifungals (fluconazole, voriconazole, posaconazole, itraconazole), diltiazem/verapamil, macrolides, protease inhibitors, and grapefruit raise levels markedly; rifampin, phenytoin, carbamazepine, and St. John's wort lower them. CYP3A5 expressers (common in some Asian and African populations) often need higher mg/kg doses. Anticipate dose changes and recheck troughs whenever an interacting drug is started or stopped.
Pitfalls
(1) IR, once-daily ER, and Envarsus XR are not mg-for-mg interchangeable — Envarsus has higher bioavailability, so a switch to it uses roughly 80% of the prior total IR daily dose; always recheck troughs after any formulation change. (2) Watch for tacrolimus toxicity: nephrotoxicity (acute vasoconstrictive and chronic), neurotoxicity (tremor, headache, seizures, PRES), hyperkalemia, hyperglycemia/new-onset diabetes, hypomagnesemia, and hypertension. (3) Targets and starting doses here are typical ranges only — the patient's own center protocol, immunologic risk, and co-immunosuppression override them. (4) Draw the level as a true trough (immediately before the next dose) or the number is uninterpretable.
Why Use It
Tacrolimus is the backbone calcineurin inhibitor for most kidney-transplant immunosuppression, and getting exposure right matters in both directions: too little risks acute rejection and graft loss, while too much drives nephrotoxicity, infection, diabetes, and the rest of the toxicity profile. Because the drug has a narrow therapeutic window and large, partly genetic variability in metabolism, clinicians start from a weight-based estimate and a time-appropriate target trough, then titrate to measured levels. This reference puts those two anchors — the starting-dose estimate and the typical target-trough band — in one place so they can be used together as a fast, safety-forward orientation. It does not replace a center's protocol or therapeutic drug monitoring; it complements them.
Tacrolimus — Starting Dose & Target Trough
Enter the recipient's weight and choose a formulation to estimate a weight-based starting dose, then select the time after transplant to look up the typical target whole-blood trough. All values are protocol-dependent estimates — your transplant center's protocol and trough-guided titration govern.
⚕ Educational reference only. Starting-dose ranges (IR ≈ 0.05–0.10 mg/kg/day in 2 divided doses; ER once-daily ≈ 0.10–0.15 mg/kg/day; Envarsus XR ≈ 0.14 mg/kg/day) and target troughs are typical, protocol- and center-specific values that vary with immunologic risk, co-immunosuppression, genotype, and drug interactions. Tacrolimus has a narrow therapeutic index; dosing is titrated to measured 12-hour troughs. Verify against your center's written protocol and current prescribing information before acting. For licensed clinicians; not a substitute for individualized assessment.
Next Steps
Use the estimate to initiate therapy, then let measured troughs and the center protocol take over.
- Confirm against the protocol. Reconcile the weight-based estimate and the target band with your transplant center's written immunosuppression protocol, the patient's immunologic risk, and the co-immunosuppression plan (steroids, mycophenolate, induction).
- Start trough monitoring. Begin checking 12-hour whole-blood troughs early (often by day 2–3 and frequently in the first weeks), and titrate the dose to the time-appropriate target rather than to the weight-based number.
- Screen for interactions and toxicity. Review the medication list for CYP3A inhibitors/inducers and counsel on grapefruit; monitor renal function, potassium, magnesium, glucose, and blood pressure.
- Recheck after any formulation switch. IR ↔ once-daily ER ↔ Envarsus XR conversions change exposure — re-measure troughs after the change.
- Pair with the allograft eGFR trend and eGFR (CKD-EPI 2021) tools to track graft function alongside CNI exposure.
Evidence & References
Typical weight-based starting dose
| Formulation | Typical initial dose |
|---|---|
| Immediate-release (IR), twice-daily | ≈ 0.05–0.10 mg/kg/day, given in 2 divided doses (per-dose ≈ ½ of the daily total) |
| Extended-release once-daily (Advagraf / Astagraf XL) | ≈ 0.10–0.15 mg/kg once daily |
| Envarsus XR, once-daily | ≈ 0.14 mg/kg once daily (higher bioavailability; switch from IR ≈ 80% of total IR daily dose) |
Practical capsule/tablet sizes (IR 0.5, 1, 5 mg; ER 0.5, 1, 5 mg; Envarsus 0.75, 1, 4 mg) mean computed doses are rounded to achievable combinations and then titrated to trough.
Typical target whole-blood trough (C₀) by period
| Time after transplant | Typical target trough |
|---|---|
| 0–1 month (early) | ≈ 8–12 ng/mL (some protocols 10–15) |
| 1–3 months | ≈ 7–10 ng/mL |
| 3–12 months | ≈ 5–8 ng/mL |
| > 12 months (maintenance) | ≈ 4–6 ng/mL (lower with low immunologic risk; higher with high risk or recent rejection) |
Ranges are representative of common kidney-transplant protocols and the cited consensus and outcome literature; KDIGO recommends a relatively high early target with stepwise reduction thereafter to limit calcineurin-inhibitor nephrotoxicity. Exact targets are center-, assay-, and regimen-specific.
References
- Kidney Disease: Improving Global Outcomes (KDIGO) Transplant Work Group. KDIGO Clinical Practice Guideline for the Care of Kidney Transplant Recipients. Am J Transplant. 2009;9(Suppl 3):S1–S155.
- Brunet M, van Gelder T, Åsberg A, et al. Therapeutic Drug Monitoring of Tacrolimus — Personalized Therapy: Second Consensus Report. Ther Drug Monit. 2019;41(3):261–307.
- Prograf (tacrolimus), Astagraf XL, and Envarsus XR (tacrolimus extended-release) — US prescribing information. Astellas / Veloxis.
