standardised allergen extract from house dust mites: clinical use

Prescribing considerations

• Initiation is restricted to clinicians experienced in allergic disease, with supervised first administration and facilities to manage immediate reactions.
• Confirm a clinically relevant history and house dust mite sensitisation before prescribing.
• Assess asthma control and lung function before initiation; treatment is an add-on rather than a substitute for asthma controllers.
• Consider cardiac disease and any previous systemic reaction to injected house dust mite immunotherapy because consequences of a systemic reaction may be greater.
• Interrupt treatment and investigate severe or persistent dysphagia or dyspepsia for possible eosinophilic oesophagitis.

Contraindications and cautions

• Hypersensitivity to an excipient
• FEV1 below 70% predicted after adequate pharmacological treatment at initiation
• Severe asthma exacerbation within the preceding three months
• Active or poorly controlled autoimmune disease, immune defect, immunodeficiency, immunosuppression or clinically relevant malignancy
• Acute severe oral inflammation or an oral wound

Monitoring

• Observe after the first administration for immediate local or systemic reactions.
• Review asthma control, reliever use and any sudden respiratory deterioration.
• Ask about the severity and persistence of oral, pharyngeal and oesophageal symptoms.
• Reassess after treatment interruptions and following oral surgery or dental extraction.

Clinical pharmacology

A sublingual allergen immunotherapy product targeting the immune response to Dermatophagoides pteronyssinus and Dermatophagoides farinae. It induces mite-specific IgG4 and a systemic antibody response capable of competing with IgE, although the full mechanism underlying clinical benefit remains uncertain.

Formulation and product differences

• The selected product is a white to off-white freeze-dried sublingual lyophilisate rather than a conventional swallowed tablet.
• Excipients include fish-derived gelatine, mannitol and sodium hydroxide; available data have not shown increased allergic-reaction risk solely from fish allergy.
• It is essentially sodium-free and requires no special storage conditions.