EVANS BLUE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for EVANS BLUE (EVANS BLUE).
Evans Blue is a diazo dye that binds reversibly to plasma proteins, primarily albumin. Its primary utility is as a visual indicator for the estimation of blood volume or plasma volume via dye dilution technique. It also has histological applications for staining myelin sheaths and detecting blood-brain barrier disruption.
| Metabolism | Evans Blue is not significantly metabolized; it is excreted unchanged in bile and to a lesser extent in urine. |
| Excretion | Primarily excreted unchanged in bile (80-90%) into feces; renal elimination accounts for <5% due to high protein binding. |
| Half-life | Terminal elimination half-life ranges from 2 to 12 hours, mean approximately 6 hours; prolonged in hepatic impairment or decreased albumin levels. |
| Protein binding | Extensively bound to albumin, >99%. |
| Volume of Distribution | Approximately 0.08–0.16 L/kg, approximating plasma volume; confined to intravascular space due to high protein binding. |
| Bioavailability | Not applicable; administered exclusively intravenously; oral bioavailability presumably negligible due to destruction in GI tract and first-pass effect. |
| Onset of Action | Intravenous: immediate binding to albumin with distribution complete within 5–10 minutes; onset of dye effect for vascular visualization is within minutes. |
| Duration of Action | Duration of staining effect on tissues (e.g., skin, sclera) may persist for 2–4 weeks due to slow release from albumin-bound depot; clinical duration for plasma volume measurement is transient. |
Adults: 0.5-1.0 mL of 0.5% solution (2.5-5 mg) IV bolus for determination of blood volume. Repeat doses must be separated by at least 1 hour due to slow clearance.
| Dosage form | INJECTABLE |
| Renal impairment | No specific guidelines; use with caution in severe renal impairment (eGFR <30 mL/min) as dye is excreted renally; consider dose reduction or avoidance. |
| Liver impairment | Child-Pugh A/B: No adjustment needed. Child-Pugh C: Use with caution as hepatic metabolism may be impaired; monitor for prolonged dye retention. |
| Pediatric use | 0.5-1.0 mL of 0.5% solution (2.5-5 mg) IV bolus, based on weight; typical dose is 0.5 mg/kg. Not recommended in infants due to risk of kernicterus. |
| Geriatric use | No specific dose adjustment; use with caution due to potential age-related renal impairment; monitor renal function and volume status. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for EVANS BLUE (EVANS BLUE).
| Breastfeeding | Evans Blue is excreted into breast milk in unknown amounts. M/P ratio not established. Due to limited data and potential for infant exposure, caution advised. Consider discontinuing breastfeeding or avoiding use in nursing mothers unless essential. |
| Teratogenic Risk | Evans Blue is a diazo dye used for plasma volume determination. No controlled human pregnancy data available. In animal studies, no teratogenic effects observed at clinical doses. Risk cannot be excluded; use only if clearly needed. First trimester: theoretical risk based on dye properties, but no evidence of malformations. Second/third trimester: may cause transient blue discoloration of neonate if administered near term; no known structural anomalies. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to Evans Blue or any component of the formulation. Should not be used in patients with porphyria (due to potential photosensitivity).
| Precautions | May cause transient hypotension or bradycardia following intravenous injection. Potential for allergic reactions including anaphylaxis. Use with caution in patients with known hypersensitivity to azo dyes. Avoid extravasation as it may cause local tissue necrosis. Not for intrathecal use. |
| Food/Dietary | No known food interactions. Fasting is not required before administration. |
| Clinical Pearls |
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| Fetal Monitoring | Monitor for hypersensitivity reactions (rash, urticaria, anaphylaxis) and extravasation (tissue necrosis). Fetal monitoring: ultrasound for fetal growth if repeated doses; neonatal observation for skin discoloration if used near delivery. |
| Fertility Effects | No human data on fertility. Animal studies: no adverse effects on fertility at clinical doses. Theoretical risk of ovarian or testicular toxicity from repeated high doses, but not reported. |
| Evans Blue is a diazo dye used historically for plasma volume determination. It binds avidly to albumin, enabling calculation of plasma volume via dye dilution. Avoid extravasation, as it causes intense blue staining of tissue. Use with caution in patients with hypersensitivity to azo dyes. Monitor for anaphylactoid reactions. Pregnancy category C; crosses placenta. |
| Patient Advice | This dye may cause temporary blue discoloration of skin, sclerae, and urine. · Inform your healthcare provider if you have allergies to dyes or any history of allergic reactions. · You may experience a metallic taste during injection. · Extravasation can cause prolonged skin staining; report any pain or swelling at injection site immediately. |