Antihistamines, mast cell stabilisers, adrenaline and immunoglobulin replacement
Receptor pharmacology of H1 antihistamines (and why second-generation drugs don't sedate), mast cell stabilisers and anti-IgE, how adrenaline's alpha and beta effects reverse anaphylaxis and why the IM thigh route is used, and the kinetics, dosing and adverse effects of immunoglobulin replacement.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- H1 antihistamines are inverse agonists. Second-generation drugs (cetirizine, loratadine, fexofenadine, bilastine) treat rhinitis and urticaria without much sedation. None reverses airway obstruction or shock.
- Mast cell stabilisers (cromoglycate, nedocromil) prevent degranulation but need regular prophylactic use. Omalizumab removes free IgE.
- Adrenaline is the only first-line drug for anaphylaxis. IM into the thigh, 0.01 mg/kg to 0.5 mg.
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Sources
- ASCIA guidelines: acute management of anaphylaxisAU/NZAustralasian Society of Clinical Immunology and Allergy, 2026 v2
- ASCIA allergic rhinitis treatment plan and clinical updateAU/NZAustralasian Society of Clinical Immunology and Allergy, 2024
- Criteria for the clinical use of immunoglobulin in Australia (Version 3)AU/NZNational Blood Authority, 2018
- Australian Medicines HandbookAU/NZAustralian Medicines Handbook Pty Ltd, 2026
- neffy (adrenaline nasal spray) approved to treat anaphylaxis in AustraliaAU/NZCSL Seqirus, 2026
- Epinephrine absorption in children with a history of anaphylaxisJournal of Allergy and Clinical Immunology (Simons et al.), 1998;101:33-7, 1998
- Epinephrine absorption in adults: intramuscular versus subcutaneous injectionJournal of Allergy and Clinical Immunology (Simons et al.), 2001;108:871-3, 2001
- Perioperative anaphylaxis management guideline: background paperAU/NZANZCA and ANZAAG, 2022
- The international EAACI/GA2LEN/EuroGuiDerm/APAAACI guideline for the definition, classification, diagnosis, and management of urticariaAllergy (Zuberbier et al.), 2022
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Turnstile bot check on sign-in and signed-out feedback