Povidone Iodine (Betadine)¶
Overview¶
| Field | Detail |
|---|---|
| Drug class | Antiseptic agent |
| Stock formulation | 10% Aqueous solution (100 mg/mL) |
| Reconstituted conc. | N/A (Ready to use) |
| Storage | Room temp; Protect from light |
Preparation¶
Skin Irritation
Povidone iodine is a known skin irritant. Ensure the negative control (normal saline) is read carefully. Testing is typically performed with aqueous solutions, not alcoholic tinctures.
Equipment needed¶
- 1 × Povidone Iodine 10% aqueous solution
- Normal saline (NS) — for IDT dilutions
- 1 mL syringes × 5 (for test doses/dilutions)
- 25 G needles
Step 1 — Prepare the SPT solution (10% — neat)¶
- Draw up 0.5–1 mL of the stock (10%) into a 1 mL syringe.
- Label: "Povidone Iodine SPT 10%".
Step 2 — Prepare IDT dilutions¶
Prepare in this order, using a fresh syringe for each step.
- IDT 0.01 mg/mL (1:10,000):
- Draw 0.1 mL of stock (100 mg/mL) into a 1 mL syringe. Add 0.9 mL NS. Mix. (This is 10 mg/mL — 1:10).
- Draw 0.1 mL of this 10 mg/mL into a new 1 mL syringe. Add 0.9 mL NS. Mix. (This is 1 mg/mL — 1:100).
- Draw 0.1 mL of this 1 mg/mL into a new 1 mL syringe. Add 0.9 mL NS. Mix. (This is 0.1 mg/mL — 1:1,000).
- Draw 0.1 mL of this 0.1 mg/mL into a new 1 mL syringe. Add 0.9 mL NS. Mix. (This is 0.01 mg/mL — 1:10,000).
- Label: "Povidone Iodine IDT 0.01 mg/mL".
Skin prick test (SPT)¶
| Reagent | Concentration |
|---|---|
| Test solution | Neat (10%) |
| 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 | 1:10,000 | 0.01 mg/mL | 0.1 mL of 0.1 mg/mL + 0.9 mL NS |
Inject: 0.05 mL intradermal. Read at 15–20 minutes. Delayed Reading: If history is suggestive of a delayed reaction (e.g., contact dermatitis), re-read at 24 and 48 hours.