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Wise et al.

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EAACI have published a set of recommendations that outline the pharmacological criteria that should be met by medications commonly used in the treatment of AR. 1170 The main thrust of the ARIA/EAACI criteria was to assess the efficacy, safety, and pharmacology of newer-generation oral H 1 antihistamines using level 1a studies. Using these criteria, a favorable risk-benefit ratio was determined for using newer-generation oral H 1 antihistamines over first-generation oral antihistamines. 1170 The evidence was further strengthened with several meta-analyses of the current data, where accurate and robust effect estimations can be derived from a large population 1171 (Table IX.B.1.a-1). The choice of a specific oral H 1 antihistamine is often based upon the dosing, onset, drug interactions, and potential cost (Table IX.B.1.a-2). Systematic reviews evaluating multiple oral H 1 antihistamines note benefits of certain drugs that may be important in deciding which drug to recommend or prescribe. Direct costs of newer-generation antihistamines are similar given the availability of many of these drugs as over-the-counter medications. In contrast, the cost of prescription-only formulations (levocetirizine and desloratadine) is much higher. Indirect costs would be expected to be similar among the newer-generation oral antihistamines given similar side-effect profiles. • Aggregate Grade of Evidence: A (Level 1a: 21 studies; Table IX.B.1.a-1). There is a preponderance of high-grade investigations that have examined oral H 1 antihistamines. Only level 1a studies are summarized in the table. • Benefit: Reduced nasal itching, sneezing, rhinorrhea, and nasal obstruction. • Harm: Mild drowsiness, fatigue, headache, nausea, and dry mouth. • Cost: Direct costs low (average $2 per daily dose). Indirect costs for newer generation agents lower than first-generation agents. 1172,1173 • Benefits-Harm Assessment: Benefits outweigh harm for use of newer-generation oral H 1 antihistamines. • Value Judgments: Due to the central nervous system side effects of the first generation oral H 1 antihistamines, their use is not recommended for typical AR. • Policy Level: Strong recommendation for use of newer-generation oral antihistamines to treat AR. • Intervention: Prescribing newer-generation oral H 1 antihistamines for patients with AR should be considered early in treatment. IX.B.1.b. Oral H 2 antihistamines.: The role of the H 2 receptor in mediating histamine related nasal symptoms in AR is controversial. Few small studies have investigated the impact of H 2 receptor antagonism, with varied results (Table IX.B.1.b). Further, no data exists comparing H 2 receptor antagonism efficacy to common modern first-line therapy such as nasal topical corticosteroids. Finally, the clinical significance of the changes associated with H 2 antihistamines has not been clearly defined. Despite these caveats, some studies support the addition of an H 2 antihistamine for patients with recalcitrant nasal airway obstruction while on oral H 1 antihistamines. There are drug-drug interactions that can occur with H 2 antihistamines through decreased gastric acidity and inhibition of P450. 1192

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Int Forum Allergy Rhinol . Author manuscript; available in PMC 2020 June 10.