Skip to content

Amoxicillin

Overview

Field Detail
Drug class Beta-lactam / aminopenicillin
Route IV (for SPT/IDT); oral (for challenge)
Stock vial 500 mg powder for injection
Reconstituted concentration 50 mg/mL (add 10 mL normal saline)
Diluent Normal saline (0.9% sodium chloride)
Storage Room temperature before reconstitution; 2–8°C after; use within 24 hours

Preparation

Before you start

Check the expiry date and vial integrity before opening. Label every syringe immediately after drawing up — never leave unlabelled syringes on the tray.

Equipment needed

  • 1 × Amoxicillin 500 mg powder vial
  • 1 × 10 mL syringe (for reconstitution)
  • Normal saline (0.9% sodium chloride) — at least 15 mL
  • 1 mL syringes × 4 (one for SPT, three for IDT dilutions)
  • 21 G needle (for vial entry)
  • 25 G needles (for drawing up dilutions)
  • Labels or marker pen

Step 1 — Reconstitute the stock vial

  1. Draw up 10 mL of normal saline into a 10 mL syringe.
  2. Inject into the Amoxicillin 500 mg vial using aseptic technique.
  3. Gently swirl the vial until the powder is completely dissolved. Do not shake.
  4. The resulting stock solution is Amoxicillin 50 mg/mL. It should appear clear to slightly yellow. Discard if cloudy, discoloured or if undissolved particles are visible.
  5. Write the date, time and your initials on the vial.

Step 2 — Prepare the SPT solution (20 mg/mL)

  1. Draw up 2 mL of the 50 mg/mL stock into a 5 mL syringe.
  2. Add 3 mL of normal saline. Mix gently by inverting.
  3. This gives Amoxicillin 20 mg/mL (SPT solution, 5 mL total).
  4. Label: "Amoxicillin SPT — 20 mg/mL".

Step 3 — 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 neat (100 mg/mL) into a 1 mL syringe. Add 0.9 mL NS. Mix. Label: "Amoxicillin 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. Label: "Amoxicillin IDT 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 1:100 1 mg/mL 0.1 mL of 10 mg/mL + 0.9 mL NS
2 1:10 10 mg/mL 0.1 mL neat + 0.9 mL NS

Inject: 0.02–0.05 mL intradermal. Read at 15–20 minutes.

Challenge (oral)

Oral graded dose protocol

Preparation: Amoxicillin oral suspension 125 mg/5 mL (25 mg/mL)

Step Dose Volume Interval
1 12.5 mg 0.5 mL 30 min
2 25 mg 1 mL 30 min
3 50 mg 2 mL 30 min
4 125 mg 5 mL 30 min
5 250 mg 10 mL 60 min observation

Notes

  • Observe a minimum of 30–60 minutes after the final dose.
  • Have adrenaline drawn up and labelled before commencing.