Pharmacological Management of Allergic Eye Disease

Question 1

Describe the hypersensitivity reactions?

Answer 1

• 4 types:
  o Type 1 – IgE mediated
  o Type 2 – Cytotoxic
  o Type 3 – Immune complex
  o Type 4 – Delayed hypersensitivity
• For allergic eye disease type 1 & type 4 are most relevant
  Overreaction of immune system – overreaction occurs in response to an antigen (which would not normally produce an immune response).
  The antigen is normally something that is not a serious threat to the body & that’s why they are called hypersensitivity reactions.

Question 2

Describe type 1 hypersensitivity reaction?

Answer 2

• Known as allergy
• IgE mediated
• IgE antibody produced after 1st exposure to an allergen (antigen) - pollen, house dust, antibiotics
  o These reactions are immediate
• Initial exposure to antigen activates b-lymphocytes which develop into plasma cells and with t-helper celss they produce IgE antibodies which are specific to that antigen
• On subsequent exposures, IgE molecules bind to mast cell & basophils causing the release of histamine & other inflammatory mediators
• When there is a repeat exposure, allergen will bind to Ige antibodies specific to the allergen
• Once bound to surface of mast cells and basophils, it causes degranulation which releases allergic mediators such as histamine, serotonin and prostaglandins into blood stream
• Causes smooth muscle contractions, vasodilation, increased mucous secretion & increased blood vessel permeability
• Reactions produced can be divided into:
  o Localised such as hayfever (seasonal allergic conjunctivitis) or asthma (these produce localised nasal congestion such as sneezing, itching, teary eyes)
  o Systemic – these can sometimes be fatal allergic responses e.g. anaphylactic shock may produce a response where the airways are obstructed or circulatory collapse
   Also often associated with reactions to drugs such as penicillin

Question 3

Describe type 4 hypersensitivity reaction?

Answer 3

• Mediated by T cells
• Delayed hypersensitivity
• Symoptoms present 48-72 hours after repeat exposure to allergen (antigen)
• Presentation of the antigen to T cells by macrophages stimulates division of the T cells and release of cytokines which then go on to attract lymphocytes
• Antigens attach to T cells causing release of cytokines which attract lymphocytes, macrophages and basophils to affected area –> which then causes degranulation of these cells & results in extensive tissue damage and inflammation
• e.g. tuberculin hypersensitivity (tuberculosis skin test), allergic contact dermatitis, transparent rejection

Question 4

What are the signs and symptoms common to allergy?

Answer 4

• Itching – hallmark of allergy
  o Caused by mast cell degranulation
  o Always consider allergy if px presents with itching
• Redness – hyperaemia of lids and conjunctiva
  o Due to vasodilation of BVs
• Swelling – chemosis of lids and conjunctiva
  o Due to increased permeability of BVs
• Discharge – consistency and amount varies
  o May be watery or sticky

Question 5

What are the subtypes of ocular allergy?

Answer 5

• Acute ocular allergy (acute allergy conjunctivitis)
• Seasonal & Perennial allergic conjunctivitis (seasonal type 1)
• Vernal keratoconjunctivitis (Type 1)
• Atopic keratoconjunctivitis (Type 4)
• CL associated papillary conjunctivitis (Mix)
  Mechanisms underlying these are either Type 1 or 4 or a mixture

Question 6

Describes papillae vs follicles?

Answer 6

• May not see in acute allergic reaction as papillae not had time to form
• Will see papillae in most allergic conjunctivitis
• Need to be able to differentiate the different types of allergy but also papillae and follicle
• Viral & allergic conjunctivitis can both present with watery red conjunctivitis eye – history & ability to distinguish between these will help you make correct diagnosis
• Viral conjunctivitis usually presents with follicular response, allergic conjunctivitis usually papillae
• Papillary conjunctivitis usually shows as flattened nodules with central vascular core
  o Most commonly seen as allergic immune response such as in vernal keratoconjunctivitis or CL associated allergic conjunctivitis
• Histopathological appearance of papillary conjunctivitis is that of a flat-top projection which are closely packed
  o Projections contain eosinophils, lymphocytes, mast cells and plasma cells in the stroma surrounding a vascular channel
• Central feeder vessel in papillae – edges are less red and centre is more red
• Follicles – seen in viral conjunctivitis and atypical bacterial conjunctivitis e.g. chlamydial conjunctivitis
  o Can also occur in response to toxins e.g. some glaucoma meds
  o Small & dome shaped – smaller than papillae
  o Don’t have a prominent central vessel – paler in centre and redder at base
• Histopathologically a lymphoid follicle is situated in the sub-epithelial space & can consist of a germinial core containing immature proliferated lymphocytes and plasma cells
• Follicles more prominent in forniceal conjunctivia, papillae more prominent in papillary conjunctiva (more central)

Question 7

What are the differentiating factors between symptoms of allergies?

Answer 7

• Rank the most likely diagnosis when finish H&S
• Consider age: e.g. in 30s with itchy eye then cannot be vernal keratoconjunctivitis (this occurs in childhood and resolves before age of 20)
• Discharge: can help you determine severity of allergy and in turn which allergy may be present
  o Watery  more on acute allergic conjunctivitis or mild seasonal allergic conjunctivitis end
  o Mucous or mucoid stringy discharge  thinking AKC or VKC (more severe ocular allergy)
• Itch:
  o Acute allergic conjunctivitis – could be animal hair or pollen that has entered eye so get unilateral set of symptoms
  o Wouldn’t usually get unilateral itching in any of the other conditions
  o Itching is more severe in VKC and AKC – also starting to get corneal signs – than in seasonal allergic conjunctivitis
• Ask if CL wearer and whether sxs improve on removal of contact lens
• Associated symptoms:
  o Associated rhinitis  thinking seasonal/perennial allergic conjunctivitis compared to VKC or AKC where would not expect associated rhinitis
  o Season that px presents in can also determine the type of allergic conjunctivitis (but also the tx you give)  e.g. present in early Spring – thinking hayfever, provide tx that is long lasting and will take them through whole season and Summer
   Whereas if px presents at end of season and had sxs for mths & mths then tx may be very different
   VKC can have seasonal exacerbations and may want to treat more aggressively at certain points of year
   CLAPC – doesn’t have a strong seasonal component – could happen at any time of year

Question 8

What is the differential diagnosis of ocular allergy?

Answer 8

• Ensure don’t just limit it to allergic conjunctival conditions
• Depending on individual case presentation may also want to include conditions also causing a red or irritated eye such as:
  o Infective conjunctivitis e.g. bacterial
  o Dry eye – or allergic conjunctivitis may be underlying their dry eye
  o Foreign bodies
  o Episcleritis

Question 9

Describe type 1 hypersensitivity reactions on 1st exposure and repeat exposure?

Answer 9

1st exposure:
* Initial inflammation reaction to a substance (allergen)
* Body recognises allergen as non-self
* Antibodies (immunoglobulins, Ig) 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 10

Describe sensitisation phase (ocular allergy)?

Answer 10

Mast cell is in resting state just before 1st exposure.
Mast cells contain prostaglandins and histamines – inflammatory mediators that control cascade of inflammatory responses (itching, increased BV permeability, vasodilation)
During sensitisation phase, an allergen presents – results in creation of IgE antibodies specific to that allergen
These IgE antibodies bind to the mast cell surface

Question 11

Describe sensitisation phase - subsequent exposures (ocular allergy)?

Answer 11

IgE created for specific allergen that has been identified as ‘non-self’
During subsequent exposures the allergen will present to the mast cells and once allergen presents to mast cell, it will become bound to IgE antibodies that were produced during sensitisation phase
As a result of the allergen binding to the IgE antibodies on the mast cell surface, the mast cell is prompted to degranulate & this causes the release of inflammatory mediators. Causes increased vessel permeability, vasodilation and itching

Question 12

Describe histamine & histamine receptors?

Answer 12

• Histamine main receptor involved in Type 1 allergic responses
• Released from mast cells and basophils
• Synthesised and stored in nearly all tissues – high conc in lungs, skin, stomach, nasal mucosa
• Histamine causes - smooth muscle contraction, increased vascular permeability, vasodilation and sensory nerve stimulation
• Histamine release can lead to severe reactions like anaphylactic shock or relatively benign presentations like seasonal allergic conjunctivitis
• 4 types of Histamine Receptors - H1 to H4
• H1 and H2 are involved in allergic response
• H1 receptors occur in many tissues including smooth muscle of the bronchi, BVs and intestine
• H2 receptors play major role in function of gastric parietal cells
• Important when think of antihistmaines that don’t have selective h1 response
• H1 and H2 present in blood vessels in the eye
• When stimulated H1 receptors cause vasodilation, increased permeability, itching, contraction of smooth muscle in both gastrointestinal tract and bronchi
• H2 receptors stimulated cause vasodilation, itching, mucous discharge and gastric secretions
• In eye, histamine release causes characteristic manifestations including itching (due to conjunctival nerve stimulation), tearing, conjunctival and lid oedema and conjunctival hyperaemia as well as a papillae reaction

Question 13

What are the two main types of anti-allergy drugs?

Answer 13

Mast cell stabilisers and anti-histamines

Question 14

Describe mast cell stabilisers?

Answer 14

• 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
• May want to use in condition like seasonal allergic conjunctivitis with ocular effects associated with allergic rhinitis and hay fever so that at start of hay fever season px would begin to take a mast cell stabiliser and that should help to control their sxs throughout that pollen season
• Depending on what pollen the px is allergic to – can get idea of which time periods the px might benefit from using the mast cell stabiliser (e.g. consider if grass or tree pollen and when may want to start tax regime based on when sxs start to present)
• Look at CMGs for this info
• If condition like perennial conjunctivits , can use last cell stabilisers prophylactically but now need to consider fact that sxs can be present all year round, e.g. px may be allergic to animal dander

Question 15

Describe sodium cromoglicate - mechanism, medicinal forms, indications, restrictions, GSL med, P med and PoM?

Answer 15

Most common mast cell stabilser used topically
Mechanism:
Mast cell stabiliser – prevents mast cell degranulation
Also prevents mediator release & thus subsequent clinical manifestations of histamine release
Delayed response of up to 2 wks
Absorption of sodium cromoglicate can be poor
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)
Cromolyn sodium inhibits mast cell degranulation. As a result its main mode of action is to prevent mediator release and its subsequent clinical manifestations. There is no evidence of antihistamine, anti-inflammatory, or vasoconstrictive activity. Absorption is poor
Restrictions
* Can be GSL, P and PoM – differences depend on indication of use , bottle size, duration of tx and px age:
GSL
* Includes opticrom – can be bought in supermarket
* Available to entry-level optometrists
* Only licenced for seasonal allergic 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
* This can help an eyecare professional to see a red eye that may not be allergic conjunctivitis
* Must contact eye care professional if symptoms have not resolved after 14 days of use
P
* Available to entry-level optometrists
* Only licenced for seasonal AND perennial conjunctivitis
* Dose 4 times daily (qds)
* Optrex allergy eyedrops
* Can use in children younger than 6yrs of age
* Advice to seek medical help if no improvement within 48 hrs
* Must contact eye care professional if sxs have not resolved after 14 days of use
* These preparations would be issued following consultation with pharmacist or optom so could be more certain of diagnosis
PoM
* NOT available to entry-level optometrists. IP optoms can prescribe these.
* 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 (P med and GSL))

Question 16

What is the dose, cautions, interactions, contraindications, undesirable effects and info on pregnancy/breastfeeding for sodium cromoglicate?

Answer 16

• Dose:
  o 4 times daily
• Cautions:
  o None for topical administration – low risk med
• Interactions:
  o None
• Contraindications:
  o Hypersensitivity to the active ingredient or excipients (common for these to be preserved with BAK so may need to use single dose unit instead of bottle to avoid these problems or px used sodium cromoglicate in past and reacted to it)
• Undesirable effects:
  o Eye stinging
• Pregnancy & breastfeeding:
  o May be used in pregnancy when benefits outweigh the risks, safe for use during breastfeeding

Question 17

What are the mechanism, medicinal forms, indications, dose, cautions, interactions, contraindications, undesirable effects and info on pregnancy & breastfeeding of Lodoxamide?

Answer 17

IP OPTOMS
Cannot be used by entry level optometrists. IP OPTOMS ONLY.
Similar action to sodium cromoglicate, but this compound is 2500x more potent in its ability to inhibit mediator release from mast cells and basophil.
Clinical improvement occurs in this drug because it inhibits eosinophils migration and decreases levels of leukotrienes and other inflammatory cells after allergen exposure.
Mechanism
* Mast cell stabilizer – prevents mast cell degranulation
Medicinal forms
* Lodoxamide (0.1%)(Alomide) (PoM)
Indications
* Allergic conjunctivitis – VKC, seasonal allergic conjunctivitis and other allergic conjunctivitises
Dose
* Four times daily
* Not to be used under the age of 4
Cautions
* None listed
Interactions
* No known interactions
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
o Mention these to px – return to see you if they happen – let them know uncommon but can happen
* Rare or very rare – nasal complaints, rash, altered taste
Usually always discuss with px the common and very common side effects and if the uncommon side effects are serious then mention these too.
Pregnancy and Breastfeeding
* Pregnancy – preferable to avoid use in pregnancy
* Breastfeeding – benefits or treatment must outweigh risks

Question 18

Describe antihistamines?

Answer 18

• Antagonistic activity at histamine receptor sites
• Known as histamine blocking drugs
• Block histamine from activating its receptors
  In allergic response, when histamine is released, it is usually uptaking by histamine receptor and causes all previously mentioned sxs.
  If taken antihistamine drug, it blocks the receptors and blocks the histamines binding to histamine receptors and prevents further symptoms within that reaction process

Question 19

Describe systemic antihistamines?

Answer 19

• Indicated for both seasonal and perennial allergic conjunctivitis.
• In specialist setting they may also be used for long term tx of atopic keratoconjunctivitis (this may be outwith scope of entry-level optom)
• Particularly recommended if other systemic symptoms (e.g. nasal congestion (allergic rhinitis)) are present.
• Available as POM, P and GSL medications.
  o Also available as GSL products in smaller quantities

Question 20

Describe sedating systemic antihistamines?

Answer 20

• Older class of drugs
• First generation antihistamine drugs
• May induce drowsiness - thought to be due to anti cholinergic effects
  o Varies between the various first generation antihistamines
  Example Drugs
• Chlorphenamine
• Clemastine – moderately sedating (should not be used when operating hazardous equipment or when driving)
  Product: Piriton (Chlorphenamine). 4mg. Oral tablets. 30 tablets (P)
  Systemic antihistamines are very commonly used in the treatment of ocular allergy and can be broadly categorised into two categories - sedating and non-sedating drugs

Question 21

Describe non-sedating systemic antihistamines?

Answer 21

Newer class of drugs; less likely to introduce drowsiness (therefore better for people who operate hazardous equipment or who drive heavy goods vehicles)
Example Drugs
* Loratadine
* Ceterizine
* Acrivastine
These drugs have a longer ½ life than 1st gen antihistamines, they can be used less frequently to obtain a sufficient therapeutic effect – can be used once or twice daily.
Product: Zirtek (Cetrizine). 10mg. Oral tablets. 7 tablets. (GSL)
* Any systemic antihistamine may induce anti-cholinergic systemic side effects:
o Dry mouth, headache, gastro-intestinal disturbances.

Question 22

Describe systemic antihistamines for children?

Answer 22

• Specific formulations for children younger than 12 years old
• Lower concentration of active ingredient – due to smaller body size of children in this age group
• Liquid syrup, rather than tablet – so easier administration
  Piriton syrup can be used from age 1 upwards
  Zirtek syrup can be used from age 6 upwards

Question 23

What is the mechanism, medicinal forms, indications, dose, cautions, interactions, contraindications, undesirable effects and info on pregnancy/breastfeeding for Chloramphenamine (systemic antihistamines)?

Answer 23

Can be used by entry-level optometrists (P meds)
Mechanism
* First generation H1 blocking drug with mild sedating effects (take into consideration pxs lifestyle and whether safe to give this or not)
Medicinal Forms
* Available oral tablet preparations
o Chlorphenamine (4mg) (Piriton) (P) (pack of 30/60)
o Chlorphenamine (4mg) (Generic) (P) (pack of 28)
* Available oral syrup preparations (useful in children)
o Chlorphenamine (2mg per 5ml) (Piriton) (P) (150ml)
o Chlorphenamine (2mg per 5ml) (Generic) (P) (150ml)
Indications
* Systemic relief of allergy such as hayfever, food allergy and drug reactions
* Can use in perennial allergic conjunctivitis if feel it is appropriate
Dose
* 4mg up to QDS in adults
* Can be used from age 1 year - see BNF for dosing based on age
Cautions
* Epilepsy, urinary retention, prostatic hypertrophy, susceptibility of angle closure glaucoma
* Can cause mydriasis (anticholinergic effects) – check anterior chamber angle prior to prescribing
o Especially consider in older pxs who may have smaller angles
Interactions
* Other drugs with anticholinergic actions (sometimes referred to as muscarinic antagonists)
* If prescribing chlorphenamine then cross check px’s list of meds with list of meds in interactions part of BNF
Contraindications
* Hypersensitivity to the active ingredient or excipients
* Should not be used in patients who have been treated with monoamine oxidase inhibitors (MAOI)(class of anti-depressants) in the preceding 14 days
Undesirable effects
* Wide ranging see BNF; includes - commonly - blurred vision, frequency unknown –depression, diarrhoea, irritability, muscle weakness, nightmares, photosensitivity reactions
Pregnancy and Breastfeeding
* Most manufacturers advise avoid use during pregnancy and breastfeeding
* It is known that people who use in 3rd trimester, it results in reaction in their baby (such as muscle weakness and trembling) or they’re born prematurely

Question 24

What are the mechanism, medicinal forms, indications, dose, cautions, interactions, contraindications, undesirable effects, and info on pregnancy/breastfeeding for Lotradine (systemic antihistamines)?

Answer 24

Can be used by entry- level optometrists
Mechanism
* Second generation H1 blocking drug
* Minimal or no anti-cholinergic effects at level it is used for in allergic eye disease – non-drowsy
Medicinal Forms
* Available oral tablet preparations
o Loratadine (10mg) (Generic) (PoM) (30 -100 tablets)
o Loratadine (10mg) (Clarityn Allergy) (GSL/P) (7 – 30 tablets)
* Available oral syrup preparations
o Loratidine (5mg/5ml)(Generic) (P) (100ml)
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
o Could be used for hayfever but since not listed couldn’t be used in perennial allergic conjunctivitis
* POM – for the symptomatic relief of allergy such as hayfever, chronic idiopathic urticaria
o Allows you to use it for perennial allergic conjunctivitis or atopic keratoconjunctivitis
o POMs are NOT available to entry-level optoms
Dose
* 10mg daily in adults
* Can be used from age 2 year – age 2-11 5mg once daily, age 12+ 10mg daily
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
Contraindications
* Hypersensitivity to the active ingredient or excipients
Undesirable effects
* Wide ranging see BNF; includes - common - drowsiness, nervousness(in children), uncommon increased appetite, headache(more common in children) insomnia rare – tachycardia, seizure, palpitations
o Discuss with px before they decide if they want to take or not
Pregnancy and Breastfeeding
* Most manufacturers advise avoid use during pregnancy and breastfeeding (can enter breastmilk)
* Not proven to be teratogenic (cause defects in foetuses) but recommended to avoid
ALWAYS consult BNF before prescribing any drug to px & think about all appropriate considerations when prescribing

Question 25

Describe topical antihistamines?

Answer 25

• First generation antihistamines
  o E.g. antazoline phosphate (comes in joint preparation with decongestant as a Pmed)
• Second generation antihistamines (all POMs so only IP optoms)
  o Olopatidine, ketotifen, azelastine, (emedastine - not currently available)

Question 26

What are the mechanism, medicinal forms, indications, dose, cautions, interactions, contraindications, undesirable effects and info on pregnancy/breastfeeding for olopatidine (topical antihistamine)?

Answer 26

IP OPTOMS
NOT available to entry level optometrists, but often on shared care schemes
Mechanism
* Selective H1 blocker, may also have inhibit the release of histamine from mast cells
* Often noted as a combination antihistamine mast cell stabiliser
Medicinal Forms
* Topical eye drops – no single dose units available at moment
* Olopatadine (1mg/ml) (PoM) Opatanol (5ml bottle)
* Olopatadine (1mg/ml) (PoM) Generic (5ml bottle)
Indications
* Seasonal Allergic Conjunctivitis
* IP Optom can prescribe OFF license, they can choose to use a med for a condition that is not indicated if they feel it is appropriate – commonly used for other allergic conditions e.g. CLAPC, perennial conjunctivitis and acute allergic conjunctivitis
Dose
* Twice daily for up to 4 months
* Gives relatively instantaneous release within few hours – but can use prophylactically
Cautions
* Related to BAK as a preservative – so suggested that should not come into to contact with soft CLs
o Put dose in in morning and make sure px doesn’t put CL in within wash-out period of drop – so within 1st 10mins – then they could put drop in just before going to bed (after taking CLs out)
Interactions
* No known interactions
Contraindications
* Hypersensitivity to the active ingredient or excipients (which may be BAK)
Undesirable effects
* Doesn’t have anti-cholinergic effects
* A number are listed - those pertinent to us -
* Common - dry eye (often seen), eye irritation, eye pain, headache, nasal dryness, altered taste, uncommon - dizziness, eye disorders, numbness, skin reactions, frequency unknown – drowsiness, dyspnoea, nausea, vomiting
o Make px aware of side effects
Pregnancy and Breastfeeding
* Not recommended during pregnancy or breastfeeding – take on case by case basis – would be IP optom or medic that decides if benefits do really outweigh risks

Question 27

Describe topical ocular decongestants?

Answer 27

• Sympathomimetic agents
• 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 (if used topically)
• Vasoconstrictive action on conjunctival blood vessels
• Reduce conjunctival hyperaemia – only sx it really relieves in ocular allergy
• 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 – as may mask signs
• No effect on underlying cause of hyperaemia
• Indicated to provide temporary relief from mild eye irritation
• May be used w/ other meds to reduce acute sxs of seasonal or perennial allergic conjunctivitis
• P meds – dosing regimen: 2-3 times per day
  Product: Optrex Red Eyes Eye Drops (naphazoline) 0.01%, 10mL. Preserved with Benzalkonium Chloride (P)
  Eye Dew Sparkling (naphazoline) 0.01%, 10mL. Preserved with Benzalkonium Chloride (P)

Question 28

What are the cautions and side-effects of ocular decongestants?

Answer 28

• 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:
  o Toxic effect of eye drops
  o Drug themselves can cause delayed hypersensitivity (type 4) to eye drops
   Conjunctival hyperaemia is exacerbated, rather than reduced
• Ocular side effect: mydriasis (action on pupil dilator muscle)
  o Check anterior chamber angle
• Systemic adrenergic effects mean that these drugs must be used with caution in patients with:
  o Cardiovascular disorders
  o Arrhythmia
  o High blood pressure
  o Diabetes
• May interact with monoamine oxidase inhibitors (MAOIs) which are used to treat depression

Question 29

What are the cautions/contraindications, interactions, side-effects, and info on pregnancy/breastfeeding for antihistamine/decongestant?
Describe the product otrivine-antistin?

Answer 29

Available to entry-level optometrists
Product: Otrivine-Antistin (Antazoline (0.5%) and Xylometazoline (0.05%)), 10ml. Preserved with BAK (P med).
* 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 (due to rebound effect))
* Not for use in children under 12 years old
* As contains a decongestant be aware of any cautions, interactions and side-effects of this drug
* Not used often – a way to prescribe an antihistamine in the short term whilst perhaps waiting on prescription of more suitable antihistamine to be used topically long term
Cautions/contraindications:
* Hypersensitivity to the active substances to any of the excipients
* Presence of narrow angle glaucoma
* Use with CLs
* Use in pxs receiving monoamine oxidase inhibitors (MAOI) or within 14 days of stopping such tx
* Use with caution in presence of hypertension, cardiac irregularities, hyperthyroidism, diabetes mellitus or phaeochromocytomas
* Not suitable for pxs suffering from dry eyes
Interactions:
* Should not be used in pxs receiving monoamine oxidase inhibitors (MAOI) or within 14 days of stopping such tx
Side-effects:
* Uncommon frequency: epistaxis (bleeding from nose)
* Unknown frequency: headache, drowsiness, eye stinging, blurred vision, mydriasis, eye irritation, tachycardia, palpitation, arrhythmia, hypertension, pallor, nausea, sweating
Pregnancy & Breastfeeding:
* Use of med during pregnancy is not recommended unless considered essential
* Not known whether active ingredients are distributed in human milk – avoid administering in nursing mothers or breast feeding should be interrupted for 48hrs after administration