Mast Cell Stabilisers

Seasonal allergic conjunctivitis peaks in the spring and in the autumn. Perennial allergic conjunctivitis is ongoing and can have a peak depending on where you live. 'Sealed up homes' in the winter are bad for it. Allergic conjunctivitis involves sustained release of histamines and prostaglandins by conjunctival mast cells. Mast cell stabilisers attenuate this release.

Severity of symptoms needs to be ascertained first. Intermittent mild-moderate itching can be solved w/eye baths, decongestants or anti-h eye drops. Moderate-severe = hyperaemia/injection, lacrimation, mucus discharge, nasal stuffiness will respond to mast cell stabs in conjunction w/oral antihistamines. Severe = chronic oedema of lid margins and conj, w/infiltrates and badass discomfort/foreign body sensation. This may also need NSAIDS or topical corticosteroids.

Guidelines for use

NB These drugs aren't 'cure-all'

• C/I - Known allergy to drugs or ingredients (BkCl??) Can do patch test to work out what Px is allergic to
  
• IND - for prophylactic use to offset the severity of ocular reactions to allergens
• NOT for occasional use or provision of short term or acute relief of the symptoms of allergic conj. That's topical ocular decongestants or antihistamines
• Dosing needs to be regular and continuous - every four or six hours depending on severity. Should start using them before peak of season to facilitate development of tolerance and to prevent palp conj changes/damage. Remember you're attenuating symptoms not actually getting rid of them
• Px education is really important - regular doses are the only way it's gonna work. Maintenance of a 'quiet' eye throughout the day may take 2 to 4 weeks of QDS although some improvement can be shown in 7 to 10 days. For VKC it could take 4 to 8 weeks to reach the maintenance state. May still need topical decongestant after extreme exposure.

Available Preps

All P Meds in 5-10ml bottles

• Sodium Cromoglicate 2% widely avail as P eg Opticrom Allergy Eye Drops, Clarityn Allergy Eye Drops (not w/anti-h like the tablets!) likely w/BkCl & EDTA. Can use w/CLs before and after but not during. Wait 5 minutes at least before putting lens in.
• Lodoxamide (2nd gen MCS) PoM Alomide (additional supply only) and P Alomide Eye Drops 0.1% concentration. P Med is indicated for Seasonal Allergic Conj & CLPC although shouldn't be used w/lenses in.
• Nedocromil Sodium avail as PoM. Canary yellow colour so can't be used w/CL wear at all

NOTE!11 Cobblestone Papillae = VKC, Lumpy = CLPC, Meaty Papillae on lower lid = chalmydial infection - refer to GP for oral MCS.

SUPPLEMENTALLLLLL: ORAL ANTI-HISTAMINES FOR ALLERGIC CONJ

Additional supply only. Very good if you have a runny nose an all. Note some older drugs induce drowsiness. Any pharm dispensing will advise Px of this. Newer antihistamines are non-sedating so there won't be any drug induced drowsiness.

Some antihistamines do have sympathomimetic potential so again their use in Px w/cardiac probs, HBP, Epilepsy, Asthma, Liver & Kidney disease is not recommended. There was a general warning in 1994 for use of some of these products esp terfenadine cos it could create cardiac arrthymias that were maybe fatal. Terfenadine is PoM. This doesn't apply to all the other antihistamines but again their use ain't recommended.

Current available SL and P Meds

• Chloramphenamine eg P Piriton, Calimal, Pollenase in 30 to 60 tab packs w/syrup for kids. Useage up to QDS.
• Acrivastine eg P Benadryl Allergy Relief 7, 12, 24 tablets. Dosage up to QDS
• Clemastine SL/P Allereze and P Tavegil. Dose = bd or up to every four hours
• Loratidine eg P Clarityn 7-14 tab packs. Once a day
• Cetirizine P Benadryl one-a-day P Cetirizine P Piriteze. Also oral syrups for paediatric use

All these prods don't have substantial risk of ADRs.