7 - Anti-allergy

Question 1

Describe Mast cells
- Location
- Effect

Answer 1

Main effector for allergy.
- Located in mucosal and epithelial tissue, where antigens from environment try to enter host
- Degranulation via IgE-allergen binding
- IgE made from mature B cells, responding from CD4+ Th2 cells
- Causes red, swell, itch, leaky BVs

Question 2

5 Ocular allergy phenotypes
- Immune mechanisms?

Answer 2

• SAC/PAC = IgE-mast cells
• VKC = Th2 mostly, with some Th1/Th17 cytokines
• AKC = Th2,Th1, and Th17
• Contract Dermato-conjunctivitis (CDC) = Th1
• GPC = Th17/Th2

Question 3

Non-pharmalogical management of ocular allergies include…

Answer 3

• Avoiding allergen
• Cold compresses + artificial tears
• Hygiene practices

Question 4

Decongestants
- Which drug (concentration)
- Mechanism
- Side effects?
- Contraindications?
- Other notes?

Answer 4

Naphazoline Hydrochloride 0.01% - 0.02%
- Alpha 1 agonist (but so low a concentration, has no effect on pupil dilator)
- Vasoconstrictor (eyes turn white within 5 minutes)

• Rebound possible, taper needed if long term use.

Contra-indications:
- Damaged/stained cornea allows higher penetration so could dilate pupil, making PAGC worse
Caution:
- Could raise BP but low concentration so unlikely
- Hyperthroidism + CV abnormalities

• When combined w/ anti-histamine, add “-A” suffix to drug name
• Pharmacist only

Question 5

List 3 antihistamines
- Combos?
- Describe the one not in a combo
– Contraindications
– Side effects

Answer 5

Most combined w/ decongestant
- Antazoline (+ naphazoline)
- Pheniramine (+ naphazoline)
- Levocabastine (not given in a combo)
These 3 are pharmacist drugs.

Levocabastine:
- Very safe + well tolerated w/ no side effects.
- BAK
Contraindication:
- Known HS to it
Adverse effects:
- Sting on instillation

Question 6

List 3 mast cell stabilisers
- Describe the one not in a combo
– Dose
– Contraindication
– Side effects

Answer 6

• Lodoxamide
• Olopatadine (combo w/ antihistamine)
• Ketotifen (combo w/ antihistamine)

Lodoxamide:
- 4x daily
Contraindication:
- Known HS
Adverse:
- Stings a little

Question 7

What’s olopatadine.
- Mechanism
- Dose
- Prescribing technique
- Contraindication
- Side effects

Answer 7

• Combo of anti-histamine and mast-cell stabilizer
• 2x daily
• It’s H1 blocking effects are delayed, so we can prescribe levocarbastine first alongside and take them off levo after a week.
  Contraindication:
• Known HS
  Side effects:
• All related to BAK

Question 8

Ketotifen?

Answer 8

• Unfunded
• Just as good as olopatadine (same mechanism)
• Drops or vials (no preservatives needed but more expensive.

Question 9

Steroids?

Answer 9

• Potent
• Short-term ocular allergy cases
• Proper dosing required, monitor side effects
• Can be used to treat SAC

Question 10

Calcineurin inhibitors?

Answer 10

• Cyclosporin + tacrolimus
• Act on T lymphocytes and inhibits calcineurin intracelluarly, which inhibits IL-2 and cytokine transcription.
• Used for DED, but considered if concurrent allergy.