Airway hyperresponsiveness (AHR)

Airway hyperresponsiveness is not a molecule or receptor but rather a *physiological state* characterized by an exaggerated narrowing of the airways in response to various stimuli that would have little or no effect on healthy individuals[1][3][5][7][8]. It is considered one of the hallmark features and diagnostic criteria for asthma, and it also occurs in chronic obstructive pulmonary disease (COPD)[4][5][7]. The condition can be triggered by allergens, environmental irritants, cold air, exercise, and other non-specific stimuli[1]. Airway hyperresponsiveness results from complex interactions involving airway inflammation, structural changes/remodeling of the airway wall, and increased contractility of airway smooth muscle[4][6]. It is typically measured using bronchial challenge tests with agents such as methacholine or histamine; patients with this condition respond at lower doses than healthy controls[3][5]. While drugs such as bronchodilators (e.g., beta2 agonists) and anti-inflammatory agents (e.g., corticosteroids) are used to treat diseases associated with airway hyperresponsiveness like asthma, these drugs do not directly target "airway hyperresponsiveness" itself but rather its underlying causes. Therefore, **airway hyperresponsiveness is not considered a therapeutic target in the sense of being a discrete molecule or receptor**, but rather an important clinical endpoint/state reflecting underlying pathophysiology[8]. *Note*: Because "airway hyperresponsiveness" is not a molecular entity but instead describes abnormal physiological reactivity at the organ/system level, the fields for canonical name/abbreviation/molecular classification/interacting drugs/mechanisms/biomarkers/safety concerns are either null or not applicable. Drugs may reduce AHR as part of their clinical benefit in asthma/COPD management; however, they act on upstream targets such as receptors or enzymes involved in inflammation and bronchoconstriction. In summary: **Airway hyperresponsiveness** should be classified as *not* being an individual druggable target molecule/receptor/enzyme/transporter/etc., but rather as an important pathophysiologic phenomenon central to several respiratory diseases[3][4][5].

Other names

Airway hyper-responsivenessBronchial hyperresponsivenessAHRAirway hyperreactivity