Allergic conditions Flashcards
Examples of sedating (old 1st gen) antihistamines
Promethazine
Chlorphenamine
Hydroxizine
Alimemazine
Promethazine
Examples of non sedating (newer 2nd gen) antihistamines
Cetirizine
Levocetirizine
Loratadine
Desloratadine
Fexofenadine
Acravastine
Uses of antihistamines
Insomnia, motion sickness, urticaria, allergic reactions, atopic dermatitis, vertigo
Side effects of antihistamines?
Urinary retention - avoid in BPH
Blurred vision
Dry mouth
Headache
Can impair driving & operating machinery
Warning of hydroxyzine
Increased risk of QT prolongation
Max doses: 100 mg for adults
50 mg for the elderly (if use cannot be avoided)
Antihistamines cautions and contra-indications
QT prolongation
Epilepsy
Pregnancy (although cetirizine and loratadine have no harmful effects)
CVD
What may be suspected if there is unexplained weight loss, arthritis, or any other unexplained ill health
systemic lupus erythematosus (chronic autoimmune disease where the body’s immune system mistakenly attacks healthy tissues)
Which antihistamines are licensed for >2 years
Cetirizine 5mg/5ml
Loratadine 10mg tabs
Promethazine 5mg/5ml
Which antihistamines are licensed for >5 years
Promethazine 10mg or 25mg tabs
What antihistamines are licensed for >6 years?
Cetirizine 10mg tabs
What are desensitizing allergen vaccines
What are their cautions
A form of treatment that aims to reduce the body’s sensitivity to allergens by gradually exposing the immune system to increasing doses of the allergen
This may cause hypersentitivity, bronchospasms, anaphylaxis
When should desensitizing allergen vaccines be used?
In presence of specialist
if monitoring for 1hrs is possible
If CPR is available
If hay fever unresponsive to other treatments
If hypersensitive to wasps and bee venom
When should you avoid desensitizing allergen vaccines
pregnant
ACEi, B blockers
Asthma
children <5 years
OMALIZUMAB (monoclonal antibody) indications
Prophylaxis of severe persistent allergic asthma
Add-on therapy for chronic spontaneous urticaria in patients who have had an inadequate response to H1 antihistamine treatment
Steps in managing anaphylaxis reaction
secure airway
manage bp
raise legs, lay flat
if unconscious / sick lay in recovery position
Adrenaline
High flow oxygen
Cetirizine once stable
By intramuscular injection of adrenaline/epinephrine CHILD UP TO 6 MONTHS
100–150 micrograms (0.1–0.15 mL), repeated after 5 minutes if necessary
By intramuscular injection of adrenaline/epinephrine CHILD 6 MONTHS - 5 YEARS
150 micrograms (0.15 mL), repeated after 5 minutes if necessary
By intramuscular injection of adrenaline/epinephrine CHILD 6 -11 YEARS
300 micrograms (0.3 mL), repeated after 5 minutes if necessary
By intramuscular injection of adrenaline/epinephrine CHILD 12-17 YEARS
500 micrograms (0.5 mL), repeated after 5 minutes if necessary; 300 micrograms (0.3 mL) should be given if child is small or prepubertal
By intramuscular injection of adrenaline/epinephrine ADULT
500 micrograms (0.5 mL), repeated after 5 minutes if necessary
Adrenaline auto-injectors: updated advice
2 adrenaline auto-injectors are prescribed, which patients should carry at all times. Those with allergic asthma, who are at increased risk of a severe anaphylactic reaction.
Ensure patient and carer are trained on use
Check expiry date before they expire
define angioedema
Swelling of the skin caused by allergic reaction
common drugs causing angioedema
ACEi
NSAIDS
B-lactam antibiotics (Penicillin and cephalosporins)
management of angioedema
adrenaline/epinephrine, corticosteroids, and antihistamines
