Antihistamines, Allergen Immunotherapy And Allergic Emergencies Flashcards
All ________________ are of potential value in the treatment of nasal allergies, particularly seasonal allergic rhinitis (hayfever), and they may be of some value in vasomotor rhinitis
antihistamines
All antihistamines are of potential value in the treatment of nasal ______________, particularly ______________ rhinitis, and they may be of some value in ______________ rhinitis
nasal allergies
seasonal allergic (hayfever)
vasomotor
Antihistamines reduce ______________ and ________________ but are usually less effective for ________________
rhinorrhoea
sneezing
nasal congestion
Antihistamines are used ________________ in the eye, in the nose, and on the skin
topically
Oral antihistamines are also of some value in preventing ____________ and are used to treat ______________ rashes, ____________, and __________; they are also used in drug allergies
urticaria
urticarial
pruritus
insect bites and stings
Antihistamines may also be given in ______________ following initial stabilisation of the patient, especially in patients with persistent cutaneous symptoms
anaphylaxis
Antihistamines may also be given in anaphylaxis following initial stabilisation of the patient, especially in patients with persistent _____________ symptoms
cutaneous
Antihistamines (including cinnarizine, cyclizine, and promethazine teoclate) may also have a role in ________________ and _______________
nausea
vomiting
Buclizine is included as an anti-emetic in a preparation for _____________
migraine
Buclizine is included as an ________________ in a preparation for migraine
anti-emetic
Antihistamines may also have a role in occasional _____________
insomnia
All older antihistamines cause sedation but ________________ and ________________ may be more sedating whereas chlorphenamine maleate and cyclizine may be less so
alimemazine tartrate
promethazine
All older antihistamines cause sedation but alimemazine tartrate and promethazine may be more sedating whereas _______________ and _________________ may be less so
chlorphenamine
cyclizine
Non-sedating antihistamines such as acrivastine, bilastine, cetirizine hydrochloride, desloratadine (an active metabolite of loratadine), fexofenadine hydrochloride (an active metabolite of terfenadine), levocetirizine hydrochloride (an isomer of cetirizine hydrochloride), loratadine and mizolastine cause less sedation and psychomotor impairment than the older antihistamines because they ___________________
penetrate the blood brain barrier only to a slight extent
The use of first-generation antihistamines in _____________ patients is potentially inappropriate (STOPP criteria) as safer, less toxic antihistamines are widely available
elderly
The use of ________________ antihistamines in elderly patients is potentially inappropriate (STOPP criteria) as safer, less toxic antihistamines are widely available
first-generation
What are the second generation antihistamines? (3)
- Cetirizine
- Fexofenadine
- Loratadine
- the fox, the satyr, and the rat
What are the main first generation antihistamines? (5)
- Diphenhydramine
- Carbinoxamine
- Clemastine
- Chlorpheniramine
- Brompheniramine
Immunotherapy using ____________________ containing house dust mite, animal dander (cat or dog), or grass pollen extract and tree pollen extract can reduce symptoms of asthma and allergic rhinoconjunctivitis
allergen vaccines
Immunotherapy using allergen vaccines containing house dust mite, animal dander (cat or dog), or grass pollen extract and tree pollen extract can reduce symptoms of ______________ and allergic __________________
asthma
rhinoconjunctivitis
Vaccines containing wasp venom extract or bee venom extract may be used to reduce the risk of severe ______________ and systemic reactions in individuals with hypersensitivity to wasp and bee stings.
anaphylaxis
An ____________ preparation of grass pollen extract is licensed for disease-modifying treatment of grass pollen-induced rhinitis and conjunctivitis, and an ____________ preparation of house dust mite extract is licensed for disease-modifying treatment of house dust mite allergic rhinitis or asthma in certain patients
oral
oral
______________ is a monoclonal antibody that binds to immunoglobulin E (IgE). It is used as additional therapy in individuals with proven IgE-mediated sensitivity to inhaled allergens, whose severe persistent allergic asthma cannot be controlled adequately with high dose inhaled corticosteroid together with a long-acting beta2 agonist
Omalizumab
What is anaphylaxis?
a severe, life-threatening, generalised or systemic hypersensitivity reaction
Anaphylaxis is characterised by rapidly developing _____________ and/or ______________ and/or ______________ problems, and is usually associated with skin and mucosal changes; prompt treatment is required.
airway
breathing
circulation
What are the most common allergens that cause anaphylaxis? (4)
- Food (e.g. peanuts, sesame, tree nuts, soy, shellfish, and cow’s milk)
- Drugs (e.g. antibacterials, aspirin and other NSAIDs, neuromuscular blocking drugs, chlorhexidine, contrast media, and vaccines)
- Venom (e.g. insect stings)
- Latex
In the case of drugs, anaphylaxis is more likely after _____________ administration
parenteral
Anaphylactic reactions may also be associated with ____________ and ____________ in foods and medicines
additives
excipients
Is refined arachis (peanut) oil present in some medical products likely to cause an allergic reaction?
Unlikely — nevertheless it is wise to check the full formula of preparations which may contain allergens
Certain patients may be at higher risk of anaphylaxis, either because of ________________ or because of _________________
an existing comorbidity (such as asthma)
an increased likelihood of repeated exposure to the same allergen (such as those with venom or food allergies)
_________________ may follow an anaphylactic reaction
Cardiopulmonary arrest; start cardiopulmonary resuscitation (CPR) immediately
What is the immediate management of anaphylaxis? (10)
- Immediately call for an ambulance or the resuscitation team
- Remove the trigger if possible (eg drug or insect stinger)
- Place patient in a comfortable (eg flat to aid in the restoration of blood pressure OR semi-recumbent if airway or breathing problems and no evidence of CV instability OR in the recovery position for unconscious patients who are breathing normally)
- IM adrenaline
- Assess response to treatment by monitoring vitals and auscultate for wheeze
- Repeat dose of IM adrenaline given after 5-min if there is no improvement in the patient’s condition
- Nebulized adrenaline may be added as an adjunct to treat upper airway obstruction (but only after treatment with IM adrenaline and NOT as an alternative)
- High flow O2 given as soon as it is available
- IV fluids for patients with which or if there is poor response to initial dose of adrenaline
- Inhaled bronchodilator therapy may also be considered for patients with persistent respiratory problems but should NOT be used as an alternative to further treatment with adrenaline
*antihistamines are NOT part of the initial emergency treatment of anaphylaxis but may be used following stabilization in patients with persistent cutaneous symptoms (same with oral steroids)
What is the dose of adrenaline used to treat anaphylaxis in adults?
IM 500 micrograms of adrenaline 1 in 1000
*same for children 12-17 yo
What is the dose of adrenaline used to treat anaphylaxis in children under 12 yo?
6-11 yo: 300 micrograms adrenaline 1 in 1000
6 mo-5 yo: 150 micrograms adrenaline 1 in 1000
Up to 6 mo: 100-150
What is the dilution of adrenaline used in CPR vs anaphylaxis?
CPR: 1 in 10,000 or 100 micrograms/mL
(1 mg for adults)
Anaphylaxis: 1 in 1,000 or 1 mg/mL
(500 micrograms for adults)
Patients who have no improvement in respiratory and/or cardiovascular problems despite _______ appropriate doses of intramuscular adrenaline/epinephrine, should have their care escalated quickly and managed as having refractory anaphylaxis
2
Nebulised adrenaline/epinephrine may be effective as an adjunct to treat upper airways obstruction caused by laryngeal oedema, but only after treatment with _______________ and not as an alternative
intramuscular adrenaline/epinephrine
Antihistamines _________ (are/are not) recommended as part of the initial emergency treatment of anaphylaxis
Are not; may be used following stabilization, especially in patients with persistent cutaneous symptoms
The routine use of corticosteroids for the emergency treatment of anaphylaxis ______ (is/is not) recommended
Is not; may be used after initial resuscitation for refractory reactions or ongoing asthma/shock
Can corticosteroids be given instead of adrenaline in the initial treatment of anaphylaxis?
Nooope; only after initial resuscitation with adrenaline for refractory reactions or ongoing asthma/shock
Oral route where possible
Refractory anaphylaxis is defined as anaphylaxis that requires ongoing treatment due to persisting respiratory and/or cardiovascular problems despite ____ appropriate doses of intramuscular adrenaline/epinephrine
2
Adrenaline/epinephrine therapy should be supported with ____________ therapy
intravenous fluid
Patients should be treated with an intravenous adrenaline/epinephrine infusion. Intravenous adrenaline/epinephrine should only be given by experienced specialists and in a setting where patients can be carefully monitored. If an intravenous infusion cannot be administered safely (e.g. due to a patient being outside a hospital setting), __________________
continue to give intramuscular adrenaline/epinephrine at 5-minute intervals while life-threatening cardiovascular and/or respiratory features persist
If pregnant, what position should patients be put in during an episode of anaphylaxis?
Lie on left side to prevent aortic compression
Where should IM adrenaline be given?
Anterolateral aspect — middle third of thigh
What are the signs of life-threatening airway problems? (2)
- Hoarse voice
2. Stridor
What are the signs of life-threatening breathing problems? (5)
- Increased work of breathing
- Wheeze
- Fatigue
- Cyanosis
- SpO2<94%
What are the signs of life-threatening circulation problems? (4)
- Low BP
- Signs of shock
- Confusion
- Reduced consciousness
What volume of fluids should be given to adults in the treatment of anaphylaxis following IM adrenaline administration?
IV fluid challenge with crystalloid — 500-1000 mL
(10 mL/kg in children)
https://www.resus.org.uk/sites/default/files/2021-04/Anaphylaxis%20algorithm%202021.pdf
How should patients be managed prior to discharge following an episode of anaphylaxis? (3)
- Provided with 2 adrenaline auto-injectors
- Trained on their correct use
- Advised to carry them at all times
The provision of adrenaline/epinephrine auto-injectors are appropriate for all patients who have had anaphylaxis, with the exception of those with a _____________
drug-induced reaction (unless future exposure to the trigger drug will be difficult to avoid)
______________ can be caused by an allergic reaction. It involves the swelling of deeper tissues, most commonly in the eyelids and lips, and sometimes the tongue and throat
Angioedema
Allergic angioedema that occurs with life-threatening airway and/or breathing and/or circulatory problems should be managed as _______________
anaphylaxis
Unlike allergic angioedema, adrenaline/epinephrine, corticosteroids, and antihistamines should not be used for the treatment of acute attacks of ______________________
Hereditary angioedema
(including attacks involving laryngeal oedema) as they are ineffective and may delay appropriate treatment—intubation may be necessary
*C1-esterase inhibitors should be used instead
What is the treatment of choice for acute hereditary angioedema?
C1-esterase inhibitors, an endogenous complement blocker derived from human plasma
Which drugs can be used for short-term prophylaxis of hereditary angioedema? (2)
- Tranexamic acid
- Danazol (unlicensed)
*started several days before planned procedures (eg dental work) and continued for 2-5 days afterwards
Non-sedating antihistamines such as certirizine hydrochloride cause less ____________ and ______________ impairment than the older antihistamines, but can still occur; sedation is generally minimal
sedation
psychomotor
Children under _______ years should not be given over-the-counter cough and cold medicines containing chlorphenamine
6
Children under 6 years should not be given over-the-counter cough and cold medicines containing ____________
chlorphenamine (a 1st gen antihistamine)
Older antihistamines should be prescribed with caution in patients with which conditions? (5)
- Epilepsy
- Prostatic hypertrophy
- Pyloroduodenal obstruction
- Susceptibility to angle-closure glaucoma
- Urinary retention
(Due to anti-cholinergic effects)
What are the common side effects of first generation antihistamines? (8)
- Impaired concentration
- Abnormal coordination
- Dizziness
- Dry mouth
- Fatigue
- Headache
- Nausea
- Blurred vision
(Due to anti-cholinergic effects)
What advice should be given to patients and carers regarding antihistamines?
Drowsiness may affect performance of skilled tasks eg cycling or driving
Sedating effects are enhanced by alcohol
Sedating effects of antihistamines are enhanced by consumption of ___________
Alcohol
Adrenaline is not licensed for the treatment of CPR in ____________ and infants with body-weight under ____________
Infants
5 kg
(But still used in this group)
Adrenaline should be prescribed with caution in which patients? (20)
- Arteriosclerosis
- Arrhythmias
- Cerebrovascular disease
- Cor pulmonale
- DM
- Elderly
- Hypercalcemia
- Hyperreflexia
- HTN
- Hyperthyroidism
- Hypokalemia
- IHD
- Obstructive cardiomyopathy
- Occlusive vascular disease
- Organic brain damage
- Pheochromocytoma
- Prostate disorders
- Psychoneurosis
- Severe angina
- Susceptibility to angle closure glaucoma
**cautions are only for non-life-threatening situations
What is the main side effect of adrenaline?
Cardiomyopathy and MI
but also may cause injection site necrosis, CNS hemorrhage, hepatic/renal/ intestinal necrosis, pulmonary edema
IM use of adrenaline in pregnancy may reduce ___________ and cause ___________, ___________, and ___________ in fetus.
Can delay second stage of labor
placental perfusion
tachycardia
cardiac irregularities
extrasystoles
**only use if benefits outweigh risk
Is adrenaline safe to administer while breastfeeding?
Yes; present in milk but poor oral bioavailability so unlikely to cause harm
What monitoring is required when administering adrenaline?
Monitor BP and ECG
Which antihistamines are used in the management of nausea and vomiting? (4)
- Cyclizine
- Cinnarizine
- Promethazine
- Buclizine
