8- Anti allergics Flashcards
What percentage of the population is affected by allergic conjunctivitis?
15-40% of the population is affected by allergic conjunctivitis
What are the two main types of allergic conjunctivitis?
Seasonal allergic conjunctivitis (SAC) and perennial allergic conjunctivitis (PAC).
How does SAC differ from PAC?
SAC is seasonal and often related to pollen (hay fever), whereas PAC occurs year-round and is triggered by allergens like animal dander or house dust mites.
What immunological mechanism causes allergic conjunctivitis?
An Immunoglobulin E (IgE) hypersensitivity response to allergens.
What happens when allergens bind to mast cells in allergic conjunctivitis?
Mast cells degranulate, releasing histamine and other inflammatory mediators, leading to symptoms.
What are the primary symptoms of allergic conjunctivitis?
Ocular itching (mostly bilateral), redness, swelling (chemosis), watery or mucoid discharge, and conjunctival papillary reaction.
What clinical feature is the hallmark of allergic conjunctivitis and distinguishes it from other types of conjunctivitis?
Ocular itching is the hallmark symptom.
What pre exisiting conditions can worsen allergic conjunctivitis symptoms ?
B,D,E
-blepharitis
- dry eye syndrome
- exposure to more allergens.
What should be done if corneal involvement is observed in allergic conjunctivitis?
The patient should be referred for a doctor’s opinion to rule out keratoconjunctivitis.
What is Sodium Cromoglycate?
It is a mast-cell stabilizer used for allergic conjunctivitis.
How is SCG classified
P medicine if ≤10ml
POM if >10ml
GSL for those over 6 years for short-term use.
How does Sodium Cromoglycate work?
It stabilizes mast cells, preventing the release of histamine and other mediators.
What are the contraindications for Sodium Cromoglycate?
3
Hypersensitivity to Sodium Cromoglycate or its components e.g. the preservative benzalkonium chloride.
Children under 6 years.
Not to be used for more than 14 days without consulting a doctor, pharmacist, orthoptist or optometrist.
How should Sodium Cromoglycate be used with contact lenses?
how many mins should you wait before reinserting CLs
Contact lenses should be removed before use and not reinserted for at least 15 minutes after application.
What is the usual dosing schedule for Sodium Cromoglycate?
1-2 drops in both eyes, four times daily.
What storage conditions are required for Sodium Cromoglycate?
Store below 30°C and protect from direct sunlight.
What is Antazoline sulfate, and how is it used?
An antihistamine used in combination with xylometazoline hydrochloride, available as Otrivine-Antistin
What are the contraindications for Antazoline sulfate?
Hypersensitivity to its components and use within 14 days of monoamine oxidase inhibitors (MAOIs).
Why must caution be exercised with Antazoline sulfate in elderly patients?
C, H, H U
there is caution if the patient has these conditions.
cardiovascular disease
hypertension
hyperthyroidism
urinary retention.
What precautions should be taken when using Antazoline with contact lenses?
Avoid wearing contact lenses during treatment as benzalkonium chloride can accumulate in lenses.
How should Antazoline be stored?
Below 25°C.
What are common side effects of Antazoline sulfate?
T, N, H, D, D
Tachycardia, nausea, headaches, dizziness, and drowsiness.
What is the dosing regimen for Antazoline sulfate?
how many drops, how many times and for how many days max
1 drop 2-3 times a day daily for 7 days max
What benefit do systemic antihistamines have when combined with other ocular treatments?
- address allergic symptoms affecting other parts of the body
- e.g. rhinitis.
Give examples of systemic antihistamines for allergic conjunctivitis.
C
Cetirizine 10mg tablets or 1mg/ml oral solution.
What are the hallmark signs of chemosis in allergic conjunctivitis?
Swelling of the conjunctiva and severe ocular itching.
How does conjunctival papillary reaction present?
The conjunctiva appears bumpy and inflamed.
What are the risks of prolonged use of Antazoline sulfate?
Rebound hyperemia and potential severe follicular conjunctivitis.
What is the mechanism of action of mast cell stabilizers in allergic conjunctivitis?
what they prevent and what stops beinf released
A: They prevent degranulation of mast cells, stopping histamine release.
What should patients avoid doing to prevent exacerbation of allergic conjunctivitis symptoms?
Avoid rubbing their eyes.
Why is seasonal allergic conjunctivitis more common in spring and early summer?
Due to increased pollen levels triggering IgE hypersensitivity reactions.
What ocular conditions often coexist with allergic conjunctivitis?
RAUE
Rhinitis, asthma, urticaria (hives), and eczema
What is the importance of spacing different eye drop medications?
what it prevents, whats the benefit and how many mins spacing
To prevent interaction and ensure proper absorption; space by 5-10 minutes.
What systemic conditions should be considered before prescribing antihistamines?
C,H,H,D
Cardiovascular disease, hypertension, hyperthyroidism, and diabetes.
How do sympathomimetic effects of xylometazoline influence its use?
It may cause angle closure and should be avoided in patients at risk.
What is the role of histamine H1 and H2 receptors in allergic conjunctivitis?
H1 receptors cause itching, while H1 and H2 together lead to redness and swelling.
What should be done if symptoms of allergic conjunctivitis worsen despite treatment?
Reevaluate for other conditions like blepharitis or keratoconjunctivitis.
What are the risks of using Antazoline in pregnancy or breastfeeding?
Potential risks to the fetus or infant, so use is only advised if benefits outweigh risks.
increased teratogenic risk.
How can patients manage mild seasonal allergies prophylactically?
By using mast cell stabilizers to prevent symptoms from starting.
What additional advice can be given to patients with hay fever-related allergic conjunctivitis?
Manage environmental exposure to allergens and use systemic antihistamines as needed.
How does perennial allergic conjunctivitis differ immunologically from seasonal?
PAC involves a hypersensitivity to persistent allergens like dust mites, whereas SAC reacts to seasonal allergens like pollen.
What is the role of NICE guidelines in managing allergic conjunctivitis?
They provide evidence-based recommendations for managing conditions like blepharitis and dry eye that exacerbate allergic symptoms.
Why might a single-use preparation of Sodium Cromoglycate be recommended?
To avoid preservative-related allergic reactions.
What trade names are associated with Sodium Cromoglycate?
Opticrom and Cromolux.
What are the possible systemic interactions with sedating antihistamines?
Enhanced sedation with CNS depressants and additive antimuscarinic effects with certain drugs.
What advice is crucial for patients using antihistamines who consume alcohol?
Avoid alcohol due to enhanced sedative effects.
Why is the Van Herick test important before prescribing xylometazoline?
To assess angle status and avoid drug-induced angle closure.
What environmental advice should be given to manage allergic conjunctivitis?
Minimize exposure to allergens such as pollen, dust, and pet dander.
How can allergic conjunctivitis affect contact lens wearers?
Allergic reactions and preservatives in eye drops can cause irritation, making lenses difficult to wear.
What is the effect of xylometazoline on blood vessels in the conjunctiva?
It constricts blood vessels to reduce redness but can cause rebound effects with prolonged use.
What symptoms might indicate a need for systemic antihistamine therapy?
Widespread allergic symptoms such as nasal congestion and skin rashes.
What is a common clinical finding in allergic conjunctivitis but not in bacterial conjunctivitis?
Allergic- bilateral presentation
Bacterial- unilateral presentation
Which systemic conditions is commonly associated with allergic conjunctivitis?
asthma
What is a dual-acting agent (both mast cell stabilizer and antihistamine)?
D) Xylometazoline
What is the primary reason for advising patients with allergic conjunctivitis not to rub their eyes?
It introduces bacteria into the conjunctiva
What is the mechanism if action of cetrizine
H1 receptor antagonist blocking histamine effects
What is the risk of Combining Topical and Systemic Antihistamines
Additive sedative effects
What is the expected side effects of SGC eye drips
Mild burning and stinging upon instillation
