L22: Antihistamines Flashcards
Histamine…
is released from Mast Cells and causes:
• Vasodilation
• Increased capillary permeability
• Increased GI and pulmonary secretions
Transportation drivers can’t recieve…
no first gen
no cetirizine
(sedating)
Most sedation 2nd generation antihistamine
Cetirizine
Side effects of antihistamines
Anticholinergic • RED as a BEET • DRY as a BONE • BLIND as a BAT→ mydriasis • MAD as a HATTER • HOT as a HARE→ vasodilation
Occupations you don’t want to sedate (give 2nd gen)
- Heavy machinery operator
- Construction workers or electricians performing tasks at elevated heights
- Mass transit (bus driver, pilot, etc)
- Health care providers working 24 hour shifts or night shift
- PA students who can not fall asleep during class
Antihistamines may used for non-allergic
conditions such as
- Gastroenteritis
- Labyrinthitis
- Motion sickness
- Insomnia
Don’t use 1st generation antihistamines in
Glaucoma: increase IOP
BPH: trigger urinary retention
Systems that might be affected by anaphylaxis
- Skin and Mucosa (90%)
- Respiratory (70%)
- GI (45%)
- Cardiac (45%)
- Hypotension, syncope, tachycardia
Systems that might be affected by anaphylaxis
- Skin and Mucosa (90%)
- Respiratory (70%)
- GI (45%)
- Cardiac (45%)
- Hypotension, syncope, tachycardia
Antihistamines approved for airline pilots that may be used after adequate trial without side effects
Loratadine (Claritin)
Fexofenadine (Allegra)
Antihistamines contraindicated in airline pilots
Cetirizine (Zyrtec)
Levocetirizine (Xyzal)
Azelastine (Asteline) Nasal Spray
Diphenhydramine (Benadryl)
If a sedating antihistamine is used in an airline pilot, they:
must be grounded for 5x the half life
Ex: Diphenhydramine→ 60 hours
1st line for allergies
Nasal steroids
Nasal steroids are contraindicated in
Glaucoma, can make it worse
Meds that increase IOP:
Steroids
Decongestants
Antihistamines
Scabies
Sarcoptes scabiei skin mite infestation:
Intense nighttime pruritus. Rash. Itchy bumps, burrow lesions
Scabies diagnosis
Clinical, or skin scraping
Scabies tx
Permethrin cream (Elimite) 5% neck to soles of feet 8-12 hours
Acute vs chronic hives
Acute hives→ <6 weeks, generally self limited
Chronic hives→ >6 weeks
Chronic autoimmune urticaria→ if negative workup
Chronic autoimmune urticaria tx
Responds well to non-sedating antihistamine.
Chronic autoimmune urticaria is associated with
Other autoimmune conditions (hypothyroidism, etc)
Poison ivy
Linear erythema on legs, arms, face. Vesicular eruption on abdomen.
Poison ivy tx
Triamcinolone (Kenalog) steroid cream (no high potency on face)
+
Non-sedating oral antihistamine
If poison ivy doesn’t improve, consider
Oral Steroid Taper
