Bilastine does not undergo any significant metabolization.Approximately, 95% is excreted intact in faeces (67%) or in urine (33%) .In the fasting state bilastine is quickly absorbed, but the absorption is slowed when it is taken with food or fruit juice.Therefore, it is recommended that bilastine is taken at least one hour before and no sooner than two hours after a meal.
Current international guidelines need to be revised in the light of the recent evidence.
In vitro studies have shown that bilastine has a high specific affinity for the H1-receptor but it has no or very low affinity for 30 other tested receptors .
The affinity for the H1 receptor is 3 and 6 times higher than for cetirizine and fexofenadine, respectively.
It belongs to the piperidine class of antihistamines as do loratadine, desloratadine, and fexofenadine (Figure 1).
Like other antihistamines bilastine is an H1 receptor inverse agonist.