Suxamethonium (Succinylcholine)¶
Overview¶
| Field | Detail |
|---|---|
| Drug class | Depolarising neuromuscular blocking agent |
| Stock vial | 100 mg/2 mL (50 mg/mL) |
| Reconstituted conc. | N/A (Ready to use) |
| Storage | Refrigerate (2–8°C) |
Preparation¶
Before you start
Ensure the vial contains 100 mg/2 mL (50 mg/mL). Check expiry and integrity. Note that SPT is NOT performed neat for Suxamethonium.
Equipment needed¶
- 1 × Suxamethonium 100 mg/2 mL vial
- Normal saline (NS) — for dilutions
- 1 mL syringes × 5 (for test doses/dilutions)
- 25 G needles
Step 1 — Prepare the SPT solution (10 mg/mL — 1:5)¶
- Draw up 0.2 mL of the stock (50 mg/mL) into a 1 mL syringe.
- Add 0.8 mL NS. Mix. (This is 10 mg/mL — 1:5).
- Label: "Suxamethonium SPT 10 mg/mL".
Step 2 — Prepare IDT dilutions¶
Prepare in this order, using a fresh syringe for each step.
-
IDT 0.1 mg/mL (1:500):
- Draw 0.1 mL of the SPT solution (10 mg/mL) into a new 1 mL syringe. Add 0.9 mL NS. Mix. (This is 1 mg/mL — 1:50).
- 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 — 1:500).
- Label: "Suxamethonium IDT 0.1 mg/mL".
-
IDT 0.01 mg/mL (1:5,000):
- Draw 0.1 mL of the 0.1 mg/mL syringe into a new 1 mL syringe. Add 0.9 mL NS. Mix. (This is 0.01 mg/mL — 1:5,000).
- Label: "Suxamethonium IDT 0.01 mg/mL".
-
IDT 0.001 mg/mL (1:50,000):
- Draw 0.1 mL of the 0.01 mg/mL syringe into a new 1 mL syringe. Add 0.9 mL NS. Mix. (This is 0.001 mg/mL — 1:50,000).
- Label: "Suxamethonium IDT 0.001 mg/mL".
Skin prick test (SPT)¶
| Reagent | Concentration |
|---|---|
| Test solution | 1:5 (10 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 | 1:50,000 | 0.001 mg/mL | 0.1 mL of 0.01 mg/mL + 0.9 mL NS |
| 2 | 1:5,000 | 0.01 mg/mL | 0.1 mL of 0.1 mg/mL + 0.9 mL NS |
| 3 | 1:500 | 0.1 mg/mL | 0.1 mL of 1 mg/mL + 0.9 mL NS |
Inject: 0.05 mL intradermal. Read at 15–20 minutes.