Pharmacology and Immunology of the Head and Neck
Core rules
Head and neck pharmacology must account for local and systemic effects. Topical nasal corticosteroids have low bioavailability but can cause epistaxis and septal irritation. Oral corticosteroids are used for sudden sensorineural hearing loss and severe inflammatory sinonasal disease, with monitoring for hyperglycemia and infection. Aminoglycoside ear drops are effective against Pseudomonas but are avoided when the tympanic membrane is perforated because of cochleovestibular toxicity. Macrolides have immunomodulatory effects in chronic rhinosinusitis but are not routine antibiotics. In immunology, type I IgE-mediated reactions drive allergic rhinitis and anaphylaxis; epinephrine is first-line for anaphylaxis. Type IV delayed hypersensitivity explains contact dermatitis from earrings or topical medications. Vaccination reduces HPV-related recurrent respiratory papillomatosis and some head and neck cancers.
Worked example
A patient with allergic rhinitis and episodic nasal obstruction uses an intranasal steroid. The drug reduces mucosal eosinophilia with minimal systemic absorption. If epistaxis develops, the technique is corrected and the septum is examined to exclude a bleeding vessel or perforation.
Traps
Do not use aminoglycoside drops indiscriminately in a perforated ear. Do not treat anaphylaxis with antihistamines instead of epinephrine. Do not expect antibiotics to resolve allergic inflammation. Do not overlook corticosteroid adverse effects in diabetic patients.