Synonym/Acronym:
Cyclosporine (Sandimmune), methotrexate (MTX, amethopterin, Folex, Rheumatrex), methotrexate sodium (Mexate), everolimus (Afinitor, Certican, Zortress), sirolimus (Rapamycin), tacrolimus (Prograf).

Common Use:
To monitor appropriate drug dosage of immunosuppressant related to organ transplant maintenance.

Specimen:
Whole blood (1 mL) collected in lavender-top tube for cyclosporine, everolimus; sirolimus; tacrolimus. Serum (1 mL) collected in a red-top tube for methotrexate; specimen must be protected from light.

Immunosuppressant	Route of Administration	Recommended Collection Time
Cyclosporine	Oral or intravenous	12 hr after dose or immediately prior to next dose
Methotrexate	Oral	Varies according to dosing protocol
	Intramuscular	Varies according to dosing protocol
Everolimus	Oral	Immediately prior to next dose
Sirolimus	Oral	Immediately prior to next dose
Tacrolimus	Oral	Immediately prior to next dose
Leucovorin therapy, also called leucovorin rescue, is used in conjunction with administration of methotrexate. Leucovorin, a fast-acting form of folic acid, protects healthy cells from the toxic effects of methotrexate.

Important note: This information must be clearly and accurately communicated to avoid misunderstanding of the dose time in relation to the collection time. Miscommunication between the individual administering the medication and the individual collecting the specimen is the most frequent cause of subtherapeutic levels, toxic levels, and misleading information used in calculation of future doses.

Normal Findings:
(Method: Immunoassay for cyclosporine and methotrexate; liquid chromatography with tandem mass spectrometry for everolimus, sirolimus, and tacrolimus)

	Therapeutic Dose		Half-Life (hr)	Volume of Distribution (L/kg)	Protein Binding (%)	Excretion
	Conventional Units	SI Units (Conventional Units × 0.832)
Cyclosporine	100–300 ng/mL renal transplant	83–250 nmol/L	8–24	4–6	90	Renal
	200–350 ng/mL cardiac, hepatic, pancreatic transplant	166–291 nmol/L	8–24	4–6	90	Renal
	100–300 ng/mL bone marrow transplant	83–250 nmol/L	8–24	4–6	90	Renal
Methotrexate	Dependent on therapeutic approach		5–9	0.4–1	50–70	Renal
	Low dose: 0.5–1 micromol/L
	High dose: Less than 5 micromol/L at 24 h; less than 0.5 micromol/L at 48 h; less than 0.1 micromol/L at 72 h
	Conventional Units	SI Units (Conventional Units × 0.832)
Everolimus	Transplant: 3–8 ng/mL		18–35 (kidney); 30–35 (liver)	128–589	75	Biliary
	Oncology: 5–10 ng/mL		18–35	128–589	75	Biliary
Sirolimus	Maintenance phase: renal transplant: 4–12 ng/mL; liver transplant: 12–20 ng/mL		46–78	4–20	92	Biliary
Tacrolimus	Maintenance phase: renal transplant: 6–12 ng/mL; liver transplant: 4–10 ng/mL; pancreas transplant: 10–18 ng/mL; bone marrow transplant: 10–20 ng/mL		10–14	1.5	99	Biliary
Therapeutic targets for the initial phase post-transplantation are slightly higher than during the maintenance phase and are influenced by the specific therapy chosen for each patient with respect to coordination of treatment for other conditions and corresponding therapies. Therapeutic ranges for everolimus, sirolimus, and tacrolimus assume concomitant administration of cyclosporine and steroids.