Week 5 - Pharmacological Management of Allergic Eye Disease

Question 1

Type 1 hypersensitivity reactions:

Answer 1

• 1st exposure:
• Initial inflammation reaction to a substance (allergen)
• Body recognises allergen as non-self
• Antibodies (immunoglobulins, ‘g) are produced to recognise the allergen in the future
- Different types: IgG, IgM, IgA, IgD, IgE

• Repeat exposure:
- Antibodies recognise the allergen
- Inflammation is initiated

Question 2

What occurs during the sensitisation phase?

Answer 2

• IgE antibodies - specific to an allergen bind to mast cell in resting state
• Allergen presents to mast cells, and bind to IgE antibodies
• Mast cell degranulates, releasing inflammatory mediators histamines and prostaglandins

Question 3

Histamine and Histamine Receptors

Answer 3

• Histamine causes - smooth muscle contaction, increased vascular permeability, vasodilation and sensory nerve stimulation
• 4 types of Histamine Receptors - H1- H4
• H1 and H2 present in blood vessels in the eye

Question 4

Action of Anti-allergy drugs

Answer 4

Site of action of anti- allergy agents is commonly:
• Mast Cell Stabilisers
- Inhibit mast cell degranulation by preventing calcium influx across mast cell membranes
- May also inhibit the activation of neutrophils, monocytes and eosophils
- Trial period of at least 7 days required to see clinical effect

• Anti Histamines
- Inhibit the actions of histamine
- Prevent histamine H1 receptor interaction

Question 5

Mast cell stabilisers:

Answer 5

• Prevent mast cells from degranulating
• Stop further release of inflammatory mediators (including histamine)
• No effect on histamine already released:
• Substantial delay (up to 2 weeks) between beginning treatment and therapeutic effect (inform patients)
• Useful for management of long-term allergic eye conditions
•Most effective when used prophylactically

Question 6

Sodium Cromoglicate: mechanism, forms and indications

Answer 6

• Mechanism
Mast cell stabiliser - prevents mast cell degranulation

• Medicinal Forms
Available topical preparations
- Sodium Cromoglicate (2%)(Opticrom) (GSL)
- Sodium Cromoglicate (2%)(Optrex Allergy) (P)
- Sodium Cromoglicate (2%) (Generic) (PoM)

• Indications
- Varies dependent on which preparation is being used and in which context (i.e. GSL, P or PoM)

Question 7

Sodium cromoglicate: GSL Restrictions

Answer 7

• Can be GSL, P and PoM - differences depend on indication of use, bottle size, duration of tx and px age:

• GSL
• Only licenced for seasonal conjunctivitis (hayfever)
• Dose 4 times daily (qds)
• Not for use in children younger than 6 years of age
• Must seek medical help if no improvement within 48 hours
• Must contact eye care professional if symptoms have not resolved after 14 days of use

Question 8

Sodium cromoglicate: P Restrictions

Answer 8

• Can be GSL, P and PoM - differences depend on indication of use , bottle size, duration of tx and px age:

• P
• Only licenced for seasonal AND perennial conjunctivitis
• Dose 4 times daily (qds)

These are removed for restrictions: as a P med
• Net for use in children younger than 6 years of age
• Must seek medical help if no improvement within 48 hours
• Must contact eye care professional if symptoms have not resolved after 14 days of use

Question 9

Sodium cromoglicate: PoM Restrictions

Answer 9

• Can be GSL, P and PoM - differences depend on indication of use, bottle size, duration of tx and px age:

• PoM
• More scope for treating wider range of allergic conditions
• Prophylaxis and symptomatic treatment of acute allergic conjunctivitis, chronic allergic conjunctivitis and vernal keratoconjunctivitis, CLAPC
• Available in larger bottle (13.5ml Vs 10ml)

Question 10

Sodium cromoglicate: cautions + interactions:

Answer 10

• Dose
Four times daily

• Cautions
None for topical administration

• Interactions
None

Question 11

Sodium cromoglicate: Contraindications, undesirable effects

Answer 11

• Contraindications
Hypersensitivity to the active ingredient or excipients

• Undesirable effects
Eye stinging

•Pregnancy and Breastfeeding
May be used in pregnancy when benefits outweigh the risks, safe for use during breastfeeding

Question 12

Lodoxamide: mechanisim, forms, indications and dose

Answer 12

• Mechanism
Mast cell stabiliser - prevents mast cell degranulation

• Medicinal Forms
- Lodoxamide (0.1%)(Alomide) (PoM)

• Indications
- Allergic conjunctivitis

• Dose
- Four times daily
- Not to be used under age 4

IP optom only

Question 13

Ladoxamide: Cautions and interactions

Answer 13

• Cautions
None listed

• Interactions
No known interactions

IP optom only

Question 14

Ladoxamide Contraindications and undesirable effects

Answer 14

• Contraindications
Hypersensitivity to the active ingredient or excipients

• Undesirable effects
- Common/very common - dry eye, eye discomfort, eye disorders, vision disorders
- Uncommon - corneal deposits, dizziness, eye inflammation, headache, nausea
- Rare or very rare - nasal complaints, rash, altered taste

Question 15

Ladoxamide for Pregnancy and Breastfeeding

Answer 15

• Pregnancy - preferable to avoid use in pregnancy
• Breastfeeding - benefits or treatment must outweigh risks

Question 16

How do antihistamines work?

Answer 16

• Antagonistic activity at histamine receptor
• Block histamine from activating receptors

Question 17

Systemic antihistamines:

Answer 17

• Indicated for both seasonal and perennial allergic conjunctivitis.

• Particularly recommended if other systemic symptoms (e.g. nasal congestion) are present.

•Available as POM, P and GSL medications.

•Also available as GSL products in smaller quantities.

Question 18

Sedating systemic antihistamines

Answer 18

• Older class of drugs
• First generation antihistamine drugs
• May induce drowsiness - thought to be due to anti cholinergic effects

Examples:
Chlorphenamine
Clemastine

Question 19

Non-Sedating Systemic Antihistamines

Answer 19

• Newer class of drugs; less likely to induce drowsiness.

Example Drugs
• Loratadine
• Ceterizine
• Acrivastine

Any systemic antihistamine may induce anti-cholinergic systemic side effects:
- Dry mouth, headache, gastro-intestinal disturbances.

Question 20

Systemic Antihistamines: Children

Answer 20

Specific formulations for children younger than 12 years old
• Lower concentration of active ingredient
• Liquid syrup, rather than tablet

Examples
Chlorphenamine
Cetirizine

Question 21

Chlorphenamine: Mechanism, Medicinal forms

Answer 21

• Mechanism
First generation H1 blocking drug with mild sedating effects

• Medicinal Forms
Available oral tablet preparations
• Chlorphenamine (4mg) (Piriton) (P) (pack of 30/60)
• Chlorphenamine (4mg) (Generic) (P) (pack of 28)

Available oral syrup preparations
• Chlorphenamine (2mg/5ml) (Piriton) (P) (150ml)
• Chlorphenamine (2mg/5ml) (Generic) (P) (150ml)

Entry Level Optometrist

Question 22

Chlorphenamine: Indications, Dose

Answer 22

• Indications
Systemic relief of allergy such as hayfever, food allergy and drug reactions

Dose
- 4mg up to QDS in adults
Can be used from age 1 year - see BF for dosing based on age

Entry Level Optometrist

Question 23

Chlorphenamine: Cautions and Interactions

Answer 23

• Cautions
Epilepsy, urinary retention, prostatic hypertrophy, susceptibility of angle closure glaucoma
• Can cause mydriasis (anticholinergic effect) - check anterior chamber angle prior to prescribing

• Interactions
Other drugs with anticholinergic actions (sometimes referred to as muscarinic antagonists)

Entry Level Optometrist

Question 24

Chorphenamine : Contraindications and undesirable effects

Answer 24

• Contraindications
Hypersensitivity to the active ingredient or excipients
Should not be used in patients who have been treated with monoamine oxidase inhibitors (MAOI) in the preceding 14 days

• Undesirable effects
Wide ranging see BF; includes - commonly - blurred vision, frequency unknown - depression, diarrhea, irritability, muscle weakness, nightmares, photosensitivity reactions

Entry Level Optometrist

Question 25

Chlorphenamine: Pregnancy and Breastfeeding

Answer 25

• Pregnancy and Breastfeeding
Most manufacturers advise avoid use during pregnancy and breastfeeding

• Lactation
Chlorphenamine maleate and other antihistamine may inhibit lactation and may be secreted in breast milk. Not to be used during lactation unless considered essential by a physician

Entry Level Optometrist

Question 26

Loratadine: Mechanism and Medicinal forms

Answer 26

• Mechanism
Second generation H1 blocking drug

• Medicinal Forms
Available oral tablet preparations
• Loratadine (10mg) (Generic) (PoM) (30 -100 tablets)
• Loratadine (10mg) (Clarityn Allergy) (GSL/P) (7 - 30 tablets)

Available oral syrup preparations
• Loratidine (5mg/5ml)(Generic) (P) (100ml)

Entry Level Optometrists

Question 27

Loratadine: Indications and Dose

Answer 27

• Indications
- Depend on the product used ( i.e. GSL, P or POM)
- GSL/P - for the symptomatic treatment of allergic rhinitis and chronic idiopathic urticarial in adults and children over the age of 2 years
- POM - for the symptomatic relief of allergy such as hayfever, chronic idiopathic urticaria

• Dose
• 10mg daily in adults
• Can be used from age 2 year - age 2-11 5mg once daily, age 12+ 10mg daily

Entry Level Optometrists

Question 28

Loratodine: Cautions and Interactions

Answer 28

• Cautions
None listed

• Interactions
A few other drugs with anticholinergic actions (sometimes referred to as muscarinic antagonists) advise avoiding use of loratidine in combination with their product due to theoretical risk of an interaction e.g. phenelzine

** Entry Level Optometrists **

Question 29

Loratodine: Contraindications and Undesirable effects

Answer 29

• Contraindications
Hypersensitivity to the active ingredient or excipients

• Undesirable effects
Wide ranging see BF; includes - common - drowsiness, nervousness(in children), uncommon increased apetite, headache more common in children) insomnia rare - tachycardia, seizure, palpitations

** Entry Level Optometrists **

Question 30

Loratodine: Pregnancy and Breastfeeding

Answer 30

• Pregnancy and Breastfeeding
Most manufacturers advise avoid use during pregnancy and breastfeeding

• Lactation
Chlorphenamine maleate and other antihistamine may inhibit lactation and may be secreted in breast milk. Not to be used during lactation unless considered essential by a physician

Question 31

Topical antihistamines

Answer 31

• First generation antihistamines
- E.g. antazoline phosphate

• Second generation antihistamines
- olopatidine, ketotifen, azelastine, (emedastine - not currently available)

Question 32

Olopatidine: Mechanism, Medical forms, indications

Answer 32

• Mechanism
Selective H1 blocker, may also have inhibit the release of histamine fro mast cells

• Medicinal Forms
Topical eye drops
• Olopatadine (1mg/ml) (PoM) Opatanol (5ml bottle)
• Olopatadine (1mg/ml) (PoM) Generic (5ml bottle)

• Indications
Seasonal Allergic Conjunctivitis

IP Optometrists

Question 33

Olopatidine: Dose, Cautions, interactions

Answer 33

• Dose
Twice daily for up to 4 months

• Cautions
Related to BAK as a preservative - so suggested that should not come into to contact with soft contact lenses

• Interactions
No known interactions.

IP Optometrists

Question 34

Olopatidine: Contraindications and Pregnancy + Breastfeeding

Answer 34

• Contraindications
- Hypersensitivity to the active ingredient or excipients

• Pregnancy and Breastfeeding
- Not recommended during pregnancy or breastfeeding Lactation
- Chlorphenamine maleate and other antihistamine may inhibit lactation and may be secreted in breast milk. Not to be used during lactation unless considered essential by a physician

** IP Optometrists **

Question 35

Olopatadine: Undesirable effects

Answer 35

• Common - dry eye, eye irritation, eye pain, headache, nasal dryness, altered taste,
• uncommon - dizziness, eye disorders, numbness, skin reactions,
• frequency unknown - drowsiness, dyspnoea, nausea, vomiting

** IP Optometrists **

Question 36

How do topical ocular decongestants work?

Answer 36

• Active ingredient: adrenergic alpha agonists
• Mimic action of sympathetic branch of autonomic nervous system
• Promote contraction of smooth muscle which lines conjunctival blood vessel walls
• Vasoconstrictive action on conjunctival blood vessels
• Reduce conjunctival hyperaemia

Question 37

Important affect of ocular decongestants:

Answer 37

• No effect on underlying cause of hyperaemia
• Allergic eye disease better managed with antihistamines or Mast cell stabilisers
• May make diagnosing ocular disease more difficult by reducing key clinical signs

Question 38

When are topical ocular decongestants used? Types?

Answer 38

• Indicated to provide temporary relief from mild eye irritation

• May be used with other medications to reduce the acute symptoms of seasonal or perennial allergic conjunctivitis

• P medicines. Dosing regimen: 2-3 times per day

Products: Naphazoline

Question 39

Topical Ocular Decongestants: Cautions and Side Effects

Answer 39

• Not for use in children younger than 12 years old
• 7 day maximum treatment period
• Excessive use (> 6 times/day) of topical decongestants may produce a rebound reaction

• Known as a conjunctival medicamentosa:
- Toxic effect of eye drops
- Delayed hypersensitivity (type 4) to eye drops

• Conjunctival hyperaemia is exacerbated, rather than reduced

Question 40

Topical Ocular Decongestants: Cautions and Side Effects (Ocular + systemic)

Answer 40

• Ocular side effect: mydriasis (action on pupil dilator muscle)
- Check anterior chamber angle

• Systemic adrenergic effects mean that these drugs must be used with caution in patients with:
• Cardiovascular disorders
• Arrhythmia
• High blood pressure
• Diabetes

Question 41

Antihistamine/decongestant

Answer 41

• Includes Antazoline- a topical antihistamine
• Includes Xylometazoline- a topical decongestant
• Indicated for the acute symptoms of seasonal and perennial allergic conjunctivitis
• Used 2-3 times per day (7 day maximum treatment period)
• Not for use in children under 12 years old

Entry level optometrists, Orthoptists