Histamine and leukotriene receptor antagonism in the treatment of allergic rhinitis: an update.

Allergic rhinitis represents a global health burden. The disease can seriously affect quality of life and is associated with multiple co-morbidities. Histamine and leukotrienes are important pro-inflammatory mediators in nasal allergic inflammation. Their actions on target cells are mediated through specific receptors and, consequently, molecules that block the binding of histamine and leukotrienes to their receptors have been important areas of pharmacological research. The published literature of the pathophysiology of histamine and leukotrienes, and the effects of histamine H(1)-receptor antagonists (H(1) antihistamines) and leukotriene antagonists in monotherapy or in combination therapy in the treatment of allergic rhinitis was reviewed. The presented results are based on the best available evidence. The efficacy of H(1) antihistamines and leukotriene antagonists (montelukast in particular) in allergic rhinitis has been established in numerous randomised placebo-controlled trials. Results from meta-analyses indicate that H(1) antihistamines and leukotriene antagonists are equally effective in improving symptoms of allergic rhinitis and quality of life, but that both drugs are less effective than intranasal corticosteroids. Data on the combination of H(1) antihistamines and leukotriene antagonists in allergic rhinitis are limited. The available evidence shows that a combined mediator inhibition has additional benefits over the use of each agent alone, but is still inferior to intranasal corticosteroids. More well designed studies are needed to fully understand the benefits of a concomitant use of these agents.