Brompheniramine maleate is a histamine H1 receptors antagonist.
Target: Histamine H1 Receptor
Brompheniramine maleate, is an antihistamine drug of the propylamine (alkylamine) class. It is readily available over the counter and is indicated for the treatment of the symptoms of the common cold and allergic rhinitis. It is a first-generation antihistamine. Brompheniramine has antidepressant properties, inhibiting reuptake of the neurotransmitter serotonin. Based on this knowledge, Arvid Carlsson and his colleagues, working at the Swedish company Astra AB, were able to derive the first marketed selective serotonin reuptake inhibitor, zimelidine, from brompheniramine. Brompheniramine had a long half-life and large volume of distribution in normal adults. It also had a prolonged antihistaminic effect in the skin as evidenced by suppression of the wheal and flare response to histamine and by suppression of pruritus [1, 2].

Alcaftadine

Alcaftadine(R89674) is a H1 histamine receptor antagonist, which is used to prevent eye irritation brought on by allergic conjunctivitis.
Target: H1 Histamine Receptor
Alcaftadine is a broad-spectrum antihistamine displaying a high affinity for histamine H1 and H2 receptors and a lower affinity for H4 receptors. alcaftadine was more effective than placebo and at least as effective as olopatadine 0.01% in preventing ocular itching at 15 minutes and at 16 hours after administration. Alcaftadine 0.025% ophthalmic solution has been approved by the U.S. Food and Drug Administration for prevention of itching associated with allergic conjunctivitis in patients over 2 years of age [1]. Alcaftadine is a safe and effective option for the prevention of ocular itching associated with allergic conjunctivitis, is dosed once daily, and is competitively priced among prescription medications for allergic conjunctivitis [2].