6.10 Dermatologic, Ophthalmic, and Ear-Nose-Throat Pharmacotherapy
Key Takeaways
- Topical corticosteroid potency is matched to the site: low potency on the face, flexures, and genitals, and mid-to-high potency on thick plaques of the trunk and limbs.
- Isotretinoin is teratogenic and in Canada is dispensed under a pregnancy prevention programme requiring two negative pregnancy tests and two forms of contraception.
- Acute angle-closure glaucoma presents with a red painful eye, a fixed mid-dilated pupil, haloes, and nausea, and is an emergency that anticholinergic and sympathomimetic drugs can precipitate.
- Prostaglandin analogues are first-line for open-angle glaucoma; counsel on iris and periocular pigmentation and eyelash growth.
- Sore throat with a Centor or McIsaac score of 0 or 1 does not warrant antibiotics, and most acute otitis media in a well child over two years can be managed with watchful waiting.
6.10 Dermatologic, Ophthalmic, and Ear-Nose-Throat Pharmacotherapy
Exam Focus: These systems supply many of the minor-ailment and nonprescription items on the Evaluating Examination. The recurring test is whether you can separate the condition that a pharmacist manages from the one that must be referred within hours.
Topical Corticosteroids: The Governing Rules
Topical corticosteroid selection is governed by potency, vehicle, site, and duration.
| Potency group | Representative agent | Typical use |
|---|---|---|
| Low | Hydrocortisone 0.5% to 2.5% | Face, eyelids, flexures, genitals, infants |
| Moderate | Betamethasone valerate 0.1%, triamcinolone 0.1% | Trunk and limbs, moderate eczema |
| High | Betamethasone dipropionate 0.05% | Thick plaques, palms and soles |
| Very high | Clobetasol propionate 0.05% | Short courses on resistant plaques; never on the face |
Vehicle matters as much as potency: ointments are the most occlusive and potent for dry, lichenified skin; creams suit weeping or intertriginous areas; lotions, foams, and solutions suit hair-bearing skin.
Quantify the dose with the fingertip unit — the amount squeezed from a 5 mm nozzle over the distal phalanx, roughly 0.5 g, which covers an area equal to two adult palms. Adverse effects of prolonged use are skin atrophy, striae, telangiectasia, hypopigmentation, perioral dermatitis, and, over large surface areas, hypothalamic-pituitary-adrenal axis suppression.
Atopic Dermatitis, Psoriasis, and Acne
Atopic dermatitis management is built on emollients applied liberally and frequently, corticosteroid for flares, and trigger avoidance. Steroid-sparing options for the face and flexures include topical calcineurin inhibitors (tacrolimus, pimecrolimus) and crisaborole. Moderate to severe disease is escalated to dupilumab or a Janus kinase inhibitor. Sedating antihistamines help sleep but do not treat the itch of eczema, which is not histamine-driven.
Psoriasis is an immune-mediated hyperproliferative disorder producing well-demarcated plaques with silvery scale. Topical therapy combines a corticosteroid with a vitamin D analogue such as calcipotriol; coal tar and salicylic acid remain useful adjuncts. Moderate to severe or joint-involving disease moves to phototherapy, methotrexate, acitretin (teratogenic, with alcohol avoidance because it converts to long-lived etretinate), apremilast, or biologics targeting tumour necrosis factor, interleukin-17, or interleukin-23. Lithium, beta-blockers, antimalarials, and abrupt systemic corticosteroid withdrawal can precipitate flares.
Acne vulgaris therapy is matched to lesion type:
- Comedonal: topical retinoid (adapalene, tretinoin). Apply at night to dry skin; expect an initial purge and photosensitivity.
- Inflammatory: add benzoyl peroxide, which also prevents antibiotic resistance, or a topical antibiotic in combination — never a topical antibiotic alone.
- Moderate to severe: oral tetracyclines (doxycycline, minocycline) for a limited course, or combined oral contraceptives and spironolactone in appropriate patients.
- Severe nodulocystic or scarring: isotretinoin. It is highly teratogenic; in Canada it is dispensed under a pregnancy prevention programme requiring negative pregnancy testing before starting and monthly thereafter, two reliable contraceptive methods, and no blood donation during therapy and for one month afterwards. Monitor lipids and liver enzymes, and counsel on dryness, photosensitivity, and mood change.
Ophthalmic Disorders
Glaucoma
Open-angle glaucoma is a chronic, painless optic neuropathy. First-line therapy is a prostaglandin analogue (latanoprost, bimatoprost) given once nightly; counsel on conjunctival hyperemia, permanent iris darkening, periocular pigmentation, and eyelash lengthening. Alternatives are topical beta-blockers (avoid in asthma, COPD, and bradyarrhythmia because of systemic absorption), alpha-2 agonists, carbonic anhydrase inhibitors, and rho kinase inhibitors.
Teach punctal occlusion: after instilling a drop, close the eye and press the inner canthus for one to two minutes. This reduces systemic absorption, which matters most for timolol. Separate different drops by at least five minutes and instil suspensions last.
Acute angle-closure glaucoma is an emergency: severe eye pain, a red eye, blurred vision with haloes around lights, a fixed mid-dilated pupil, headache, and vomiting. Anticholinergics, sympathomimetic decongestants, and topiramate can precipitate it in anatomically predisposed eyes. Refer immediately.
Red eye triage
| Presentation | Likely cause | Action |
|---|---|---|
| Bilateral itch, stringy discharge, seasonal | Allergic conjunctivitis | Ocular antihistamine or mast cell stabiliser |
| Watery discharge, recent upper respiratory infection, one eye then the other | Viral conjunctivitis | Supportive care, strict hygiene |
| Purulent discharge, lids stuck on waking | Bacterial conjunctivitis | Often self-limiting; topical antibiotic where indicated |
| Pain, photophobia, reduced vision, contact lens wear, or trauma | Keratitis, uveitis, angle closure | Urgent referral |
Never recommend an ocular corticosteroid without a diagnosis; used in herpes simplex keratitis it can lead to corneal perforation.
Dry eye and macular degeneration
Dry eye is managed with preservative-free artificial tears for frequent dosing, lid hygiene, and review of contributing anticholinergic drugs. In intermediate age-related macular degeneration, an antioxidant and zinc supplement of the AREDS2 formulation slows progression; the beta-carotene of the original formulation was removed because it increased lung cancer risk in smokers.
Ear, Nose, and Throat
Allergic rhinitis responds best to an intranasal corticosteroid, which outperforms oral antihistamines for congestion. Counsel on the technique that prevents epistaxis: aim the spray away from the septum, toward the outer wall of the nostril, and do not sniff hard. Second-generation oral antihistamines are useful for sneeze and itch. Topical decongestants must be limited to three consecutive days to avoid rhinitis medicamentosa.
Sore throat is triaged with the Centor criteria as modified by McIsaac: fever above 38 degrees Celsius, absence of cough, tender anterior cervical lymphadenopathy, tonsillar exudate, and age (3 to 14 adds a point, 45 or older subtracts one). A score of 0 or 1 needs no antibiotic or testing. Higher scores prompt testing, with penicillin or amoxicillin first-line and a macrolide reserved for true penicillin allergy.
Acute otitis media in a well child older than two years with mild symptoms can be managed with analgesia and watchful waiting for 48 hours. Amoxicillin at high dose is first-line when antibiotics are indicated. Otitis externa ("swimmer's ear") is treated with topical drops; an intact tympanic membrane must be confirmed before using aminoglycoside-containing drops because of ototoxicity risk.
Cerumen impaction is treated with a softening agent such as mineral oil or carbamide peroxide; irrigation is contraindicated with perforation, tubes, or recent ear surgery. Ménière disease combines episodic vertigo, fluctuating hearing loss, tinnitus, and aural fullness, and is managed with sodium restriction, diuretics, and vestibular suppressants for acute attacks.
A parent asks for a topical corticosteroid for a toddler's facial eczema. Which product is most appropriate?
A 61-year-old presents with a painful red eye, blurred vision with haloes around lights, a fixed mid-dilated pupil, and vomiting. He recently started an oral antihistamine-decongestant product. What is the correct action?
Which counselling point is specific to a patient starting latanoprost eye drops?
A 30-year-old has a sore throat with cough, no fever, and no tender cervical nodes or tonsillar exudate. What is the appropriate management?