3.4. Antihistamines, hyposensitisation, and allergic emergencies
3.4.1. Antihistamines
Prescribing Notes:
The MHRA published advice relating to hydroxyzine in April 2015 advising that the maximum adult daily dose is now 100mg and advising that, due to the risk of QT interval prolongation and Torsade de Pointes, it should not be prescribed to people with prolonged QT interval or risk factors for QT interval prolongation.
For further information, seen the MHRA guidance.
3.4.2. Allergen Immunotherapy
Restrictions:
Use as add-on maintenance treatment in adult patients with severe eosinophilic asthma inadequately controlled despite high-dose inhaled corticosteroids plus long-acting beta-agonists is restricted to specialist use only in patients with blood eosinophils ≥150 cells/microlitre, and either ≥4 prior asthma exacerbations needing systemic corticosteroids in the previous 12 months or treatment with continuous oral corticosteroids over the previous 6 months.
Restrictions:
Restricted to specialist use for patients with severe asthma with type 2 inflammation and blood eosinophils ≥150 cells/microlitre and FeNO ≥25 parts per billion, and ≥4 exacerbations in the 12 months prior to initiating biologic treatment (anti-IgE or anti-IL-5 therapies) and who still experience ≥2 exacerbations per year despite this biologic treatment.
Restrictions:
Add-on treatment for severe refractory eosinophilic asthma in adult patients: restricted to specialist use in patients who have at least 150 cells per microlitre (0.15 x 109/L) at initiation of treatment and have had at least four asthma exacerbations in the preceding year or are receiving maintenance treatment with oral corticosteroids (regional protocol in development).
Prescribing Notes:
The following indications are not recommended by SMC and are non-Formulary:
- Add-on therapy with intranasal corticosteroids for the treatment of adult patients with severe chronic rhinosinusitis with nasal polyps for whom therapy with systemic corticosteroids and/or surgery do not provide adequate control
- Add-on treatment for adult patients with inadequately controlled hypereosinophilic syndrome without an identifiable non-haematologic secondary cause
- As an add-on treatment for patients aged 6 years and older with relapsing-remitting or refractory eosinophilic granulomatosis with polyangiitis (EGPA).
Restrictions:
Restricted to specialist use for the following indications:
- Use in adults with severe persistent allergic asthma is restricted to use in accordance with local protocols and SMC advice.
- Use to improve asthma control in children with severe persistent allergic asthma is restricted to those patients who are prescribed chronic systemic steroids and in whom all other treatments have failed.
- Use as an add-on therapy for chronic spontaneous urticaria is restricted to specialist use in accordance with local protocol in patients who have an inadequate response to combination therapy with H1 antihistamines, leukotriene receptor antagonists (LTRA) and H2 antihistamines
Prescribing Notes:
Non-formulary indication:
As add-on therapy with intranasal corticosteroids (INC) for the treatment of adults (18 years and above) with severe chronic rhinosinusitis with nasal polyps for whom therapy with INC does not provide adequate disease control (non-submission to SMC).
Restrictions:
Restricted to specialist use in adults and adolescents 12 years and older with severe asthma who have either:
- Experienced at least three exacerbations in the previous year and are not receiving maintenance treatment with oral corticosteroids or
- Have blood eosinophils ≥150 cells/microlitre and are receiving maintenance treatment with oral corticosteroids.
3.4.3. Allergic emergencies
Prescribing Notes:
- Includes autoinjector devices for self-administration (e.g. Jext® or Epipen® range of devices)
- It should be noted that the recommended administration technique for different devices can vary. When a device is changed, either by the manufacturer or by changing brand, it is essential that patients and carers receive clear instructions on the use of the device prescribed.
Patients should be made aware of the importance of checking expiry dates.
Restrictions:
Use for the routine prevention of recurrent attacks of hereditary angioedema (HAE) is restricted to specialist use in patients who experience ≥ two clinically significant attacks per month.
Restrictions:
Treatment of acute angioedema attacks in adults and adolescents with hereditary angioedema (HAE) due to C1 esterase inhibitor deficiency is restricted to specialist use only.
Restrictions:
It is restricted to specialist use only on the advice of the Immunology Service.
Restrictions:
Restricted to specialist use only in patients with hereditary angioedema (HAE) type I or II, who would otherwise be considered for long-term prophylaxis treatment with C1-esterase inhibitor.