Brompheniramine ((±)-Brompheniramine) is a potent, orally active alkylamine class antihistamine and a selective antagonist of the histamine H1 receptor (Kd = 6.06 nM). It has applications in the research of allergic rhinitis and exhibits anticholinergic, antidepressant, and anesthetic properties. Brompheniramine blocks calcium channels, sodium channels, and hERG channels with IC50 values of 16.12 μM, 21.26 μM, and 0.90 μM, respectively [1] [2] [3] [4].

Brompheniramine, at concentrations ranging from 0.1-100 μM, inhibits hERG K+ channels in CHO cells in a concentration-dependent manner, with an IC50 value of 0.90±0.14 μM. This effect is observed through the reduction of peak tail current amplitude at -60 mV, following a depolarization-repolarization protocol [3]. Additionally, brompheniramine at 1, 10, and 100 μM concentrations significantly shortens the APD50 and depresses the plateau phase of the action potential in guinea pig papillary muscle, while at 10 and 100 μM, it slightly prolongs the APD90 [3]. Furthermore, brompheniramine reduces the amplitude of Ca2+ channel currents in rat ventricular myocytes by 14.1±1.1%, 31.1±5.8%, 38.0±3.8%, and 90.2±3.7% at 0.1, 1, 10, and 100 μM, respectively [3]. The compound also blocks muscarinic cholinergic receptors in human CHO cells [4].

Brompheniramine (0.3-3 μM; SC, single dosage) elicits dose-dependent cutaneous analgesia in male Sprague-Dawley rats [1]. Administered via a single subcutaneous injection in doses ranging from 0.3 to 3.0 μM, it resulted in cutaneous analgesia with an effective concentration (EC 50) of 0.66 μM, alongside an extended duration of analgesia.