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Ketamine

Overview

Field Detail
Drug class NMDA receptor antagonist / Dissociative anaesthetic
Stock vial 100 mg/mL, 500 mg/5 mL (100 mg/mL) or 1000 mg/10 mL (100 mg/mL)
Reconstituted conc. N/A (Ready to use)
Storage Room temp; Protect from light

Preparation

Before you start

Ensure the vial contains 100 mg/mL. Check expiry and integrity. Note that Ketamine is a Schedule 8 (S8) medication and requires appropriate handling and witnessing.

Equipment needed

  • 1 × Ketamine 100 mg/mL vial
  • Normal saline (NS) — for IDT dilutions
  • 1 mL syringes × 4 (for test doses/dilutions)
  • 25 G needles

Step 1 — Prepare the SPT solution (100 mg/mL — neat)

  1. Draw up 0.5–1 mL of the stock (100 mg/mL) into a 1 mL syringe.
  2. Label: "Ketamine SPT 100 mg/mL".

Step 2 — Prepare IDT dilutions

Prepare in this order, using a fresh syringe for each step.

  1. IDT 10 mg/mL (1:10):

    • 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).
    • Label: "Ketamine IDT 10 mg/mL".

  2. IDT 1 mg/mL (1:100):

    • Draw 0.1 mL of the 10 mg/mL syringe into a new 1 mL syringe. Add 0.9 mL NS. Mix. (This is 1 mg/mL — 1:100).
    • Label: "Ketamine IDT 1 mg/mL".

  3. IDT 0.1 mg/mL (1:1,000):

    • Draw 0.1 mL of the 1 mg/mL syringe into a new 1 mL syringe. Add 0.9 mL NS. Mix. (This is 0.1 mg/mL — 1:1,000).
    • Label: "Ketamine IDT 0.1 mg/mL".

Skin prick test (SPT)

Reagent Concentration
Test solution Neat (100 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 0.1 mg/mL 0.1 mL of 1 mg/mL + 0.9 mL NS
2 1:100 1 mg/mL 0.1 mL of 10 mg/mL + 0.9 mL NS
3 1:10 10 mg/mL 0.1 mL neat + 0.9 mL NS

Inject: 0.05 mL intradermal. Read at 15–20 minutes.