Pharmacology of major drug classes used to treat immunologic and allergic conditions
Drug classes
- Drug classes for allergic conditions target different steps of the Type I hypersensitivity cascade - from mediator release to receptor blockade to broader immune suppression
- Antihistamines are among the most commonly used over-the-counter and prescribed drug classes globally
| Class | Example | Use |
|---|---|---|
| H1 antihistamines (2nd gen) | Cetirizine, loratadine, fexofenadine | Allergic rhinitis, urticaria - preferred over 1st generation (non-sedating) |
| H1 antihistamines (1st gen) | Promethazine, diphenhydramine | Sedating; more anticholinergic side effects; largely superseded for routine allergy |
| Corticosteroids | Intranasal, inhaled, oral, IV | Suppress the broader inflammatory cascade - not just histamine; used across severity spectrum |
| Leukotriene receptor antagonists | Montelukast | Add-on for allergic rhinitis/asthma; neuropsychiatric adverse effects now carry a specific warning |
| Mast cell stabilisers | Sodium cromoglicate | Prophylactic only, not for acute treatment |
| Anti-IgE biologic | Omalizumab | Severe allergic asthma/chronic urticaria refractory to standard therapy |
| Adrenaline | IM adrenaline (EpiPen) | First-line and only life-saving treatment for anaphylaxis - acts on alpha/beta receptors, not histamine pathways |
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