Discovery of the novel and potent histamine H1 receptor antagonists for treatment of allergic diseases

Desloratadine, a second-generation histamine H1 receptor antagonist, has established itself as a first-line drug for the treatment of allergic diseases. Despite its effectiveness, desloratadine exhibits an antagonistic effect on muscarinic M3 receptor, which can cause side effects such as dry mouth and urinary retention, ultimately limiting its clinical application. Herein, we describe the discovery of compound Ⅲ-4, a novel H1 receptor antagonist with significant H1 receptor antagonistic activity (IC50 = 24.12 nM) and enhanced selectivity towards peripheral H1 receptor. In particular, Ⅲ-4 exhibits reduced M3 receptor inhibitory potency (IC50 > 10,000 nM) and acceptable hERG inhibitory activity (17.6 ± 2.1 μM) compare with desloratadine. Additionally, Ⅲ-4 exhibits favorable pharmacokinetic properties, as well as in vivo efficacy and safety profiles. All of these reveal that Ⅲ-4 has potential to emerge as a novel H1 receptor antagonist for the treatment of allergic diseases. More importantly, the compound Ⅲ-4 (HY-078020) has recently been granted clinical approval.

Effects of single or combined histamine H1-receptor and leukotriene CysLT1-receptor antagonism on nasal adenosine monophosphate challenge in persistent allergic rhinitis

BACKGROUND

The effects of single or combined histamine H(1)-receptor and leukotriene CysLT(1)-receptor antagonism on nasal adenosine monophosphate (AMP) challenge in allergic rhinitis are unknown.

OBJECTIVE

We elected to study the effects of usual clinically recommended doses of fexofenadine (FEX), montelukast (ML) and FEX + ML combination, compared with placebo (PL), on nasal AMP challenge in patients with persistent allergic rhinitis.

METHODS

Twelve patients with persistent allergic rhinitis (all skin prick positive to house dust mite) were randomized in a double-blind cross-over fashion to receive for 1 week either FEX 180 mg, ML 10 mg, FEX 180 mg + ML 10 mg combination, or PL, with nasal AMP challenge performed 12 h after dosing. There was a 1-week washout period between each randomized treatment. The primary outcome measure was the maximum percentage peak nasal inspiratory flow (PNIF) fall from baseline over a 60-min period after nasal challenge with a single 400 mg ml(-1) dose of AMP. The area under the 60-min time-response curve (AUC) and nasal symptoms were measured as secondary outcomes.

RESULTS

There was significant attenuation (P < 0.05) of the mean maximum percentage PNIF fall from baseline after nasal AMP challenge vs. PL, 48; with FEX, 37; 95% confidence interval for difference 2, 20; ML, 35 (4, 22); and FEX + ML, 32 (7, 24). The AUC (%.min) was also significantly attenuated (P < 0.05) vs. PL, 1893; with FEX, 1306 (30, 1143); ML, 1246 (214, 1078); and FEX + ML, 1153 (251, 1227). There were no significant differences for FEX vs. ML vs. FEX + ML comparing either the maximum or AUC response. The total nasal symptom score (out of 12) was also significantly improved (P < 0.05) vs. PL, 3.3; with FEX, 2.1 (0.3, 2.0); ML, 2.0 (0.5, 1.9); and FEX + ML, 2.5 (0.1, 1.4).

CONCLUSION

FEX and ML as monotherapy significantly attenuated the response to nasal AMP challenge and improved nasal symptoms compared with PL, while combination therapy conferred no additional benefit.