Patent Blue (Isosulfan Blue)¶
Overview¶
| Field | Detail |
|---|---|
| Drug class | Triphenylmethane dye / Lymphatic mapping agent |
| Stock formulation | 2.5% (25 mg/mL) or 10% (100 mg/mL) |
| Reconstituted conc. | N/A (Ready to use) |
| Storage | Room temp; Protect from light |
Preparation¶
Before you start
Check the concentration. Usually 2.5% (25 mg/mL). Note that Patent Blue and Isosulfan Blue are potent triggers for anaphylaxis and can interfere with pulse oximetry readings.
Equipment needed¶
- 1 × Patent Blue 25 mg/mL vial
- Normal saline (NS) — for IDT dilutions
- 1 mL syringes × 3 (for test doses/dilutions)
- 25 G needles
Step 1 — Prepare the SPT solution (25 mg/mL — neat)¶
- Draw up 0.5–1 mL of the stock (25 mg/mL) into a 1 mL syringe.
- Label: "Patent Blue SPT 25 mg/mL".
Step 2 — Prepare IDT dilutions¶
Prepare in this order, using a fresh syringe for each step.
- IDT 0.025 mg/mL (1:1,000):
- Draw 0.1 mL of stock (25 mg/mL) into a 1 mL syringe. Add 0.9 mL NS. Mix. (This is 2.5 mg/mL — 1:10).
- Draw 0.1 mL of this 2.5 mg/mL into a new 1 mL syringe. Add 0.9 mL NS. Mix. (This is 0.25 mg/mL — 1:100).
- Draw 0.1 mL of this 0.25 mg/mL into a new 1 mL syringe. Add 0.9 mL NS. Mix. (This is 0.025 mg/mL — 1:1,000).
- Label: "Patent Blue IDT 0.025 mg/mL".
Skin prick test (SPT)¶
| Reagent | Concentration |
|---|---|
| Test solution | Neat (25 mg/mL) |
| Positive control | Histamine 10 mg/mL |
| Negative control | Normal saline |
Interpretation: Wheal ≥3 mm vs negative control = positive.
Intradermal test (IDT)¶
Dilution series¶
| Step | Dilution | Concentration | Preparation |
|---|---|---|---|
| 1 | 1:1,000 | 0.025 mg/mL | 0.1 mL of 0.25 mg/mL + 0.9 mL NS |
Inject: 0.05 mL intradermal. Read at 15–20 minutes.