Antazoline is an antagonist of histamine H1 receptors. It selectively bind to but does not activate histamine H1 receptors, thereby blocking the actions of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms brought on by histamine. Antazoline in combination with naphazoline (VASOCON-A®) is indicated to relieve the symptoms of allergic conjunctivitis.

Tripelennamine (sold as Pyribenzamine by Novartis) is a drug that is used as an antipruritic and first-generation antihistamine. Histamine acting on H1-receptors produces vasodilatation, hypotension, flushing, headache, tachycardia, and bronchoconstriction. Histamine also increases vascular permeability and potentiates pain. Tripelennamine can be used in the treatment of asthma, hay fever, rhinitis, and urticaria, but is now less common as newer antihistamines have replaced it.

Tripelennamine (sold as Pyribenzamine by Novartis) is a drug that is used as an antipruritic and first-generation antihistamine. Histamine acting on H1-receptors produces vasodilatation, hypotension, flushing, headache, tachycardia, and bronchoconstriction. Histamine also increases vascular permeability and potentiates pain. Tripelennamine can be used in the treatment of asthma, hay fever, rhinitis, and urticaria, but is now less common as newer antihistamines have replaced it.

Antazoline is an antagonist of histamine H1 receptors. It selectively bind to but does not activate histamine H1 receptors, thereby blocking the actions of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms brought on by histamine. Antazoline in combination with naphazoline (VASOCON-A®) is indicated to relieve the symptoms of allergic conjunctivitis.

Methapyrilene is an antihistamine and anticholinergic of the pyridine chemical class which was developed in the early 1950s. It was sold under the trade names Co-Pyronil and Histadyl EC. It has relatively strong sedative effects, to the extent that its primary use was as a medication for insomnia rather than for its antihistamine action. Together with scopolamine, it was the main ingredient in Sominex, Nytol, and Sleep-Eze. It also provided the sedative component of Excedrin PM. Manufacturers voluntarily withdrew methapyrilineb drug products from the market in May and June 1979, when methapyrilene was demonstrated to cause liver cancer in rats when given chronically.

Methapyrilene is an antihistamine and anticholinergic of the pyridine chemical class which was developed in the early 1950s. It was sold under the trade names Co-Pyronil and Histadyl EC. It has relatively strong sedative effects, to the extent that its primary use was as a medication for insomnia rather than for its antihistamine action. Together with scopolamine, it was the main ingredient in Sominex, Nytol, and Sleep-Eze. It also provided the sedative component of Excedrin PM. Manufacturers voluntarily withdrew methapyrilineb drug products from the market in May and June 1979, when methapyrilene was demonstrated to cause liver cancer in rats when given chronically.

There is not much available information about thenyldiamine, is known, that it is used as antihistamine and for the treatment of asthma and bronchitis.

Cloperastine (INN) or cloperastin is an antitussive and antihistamine that is marketed as a cough suppressant in Japan, Hong Kong, and in some European countries. It was first introduced in 1972 in Japan, and then in Italy in 1981. The precise mechanism of action of cloperastine is not fully clear, but several different biological activities have been identified for the drug, of which include: ligand of the gamma1 receptor (Ki = 20 nM) (likely an agonist), GIRK channel blocker (described as "potent"), antihistamine (Ki = 3.8 nM for the H1 receptor), and anticholinergic. Cloperastine possesses dual activity. It also acts as a mild bronchorelaxant and has antihistaminic activity, without acting on the central nervous system or the respiratory center.

Cloperastine (INN) or cloperastin is an antitussive and antihistamine that is marketed as a cough suppressant in Japan, Hong Kong, and in some European countries. It was first introduced in 1972 in Japan, and then in Italy in 1981. The precise mechanism of action of cloperastine is not fully clear, but several different biological activities have been identified for the drug, of which include: ligand of the gamma1 receptor (Ki = 20 nM) (likely an agonist), GIRK channel blocker (described as "potent"), antihistamine (Ki = 3.8 nM for the H1 receptor), and anticholinergic. Cloperastine possesses dual activity. It also acts as a mild bronchorelaxant and has antihistaminic activity, without acting on the central nervous system or the respiratory center.

Thiazinamium is an anti-cholinergic phenothiazine deriva¬tive, which also has antihistaminic properties. Intramuscular injection of Thiazinamium induces considerable bronchodilatation, but inconsistent results have been obtained after oral administration. The bioavailability of oral Thiazinamium is only 2-3% of that occurring after intramuscular injection. Intrarectal Thiazinamium is slightly better absorbed (3-9%). The elimination half-life of the parenteral drug is short, being about 20 minutes in most patients. Thiazinamium has been available for the treatment of asthma since the early 1960s but currently withdrawn in most countries. Compared with inhaled ipratropium bromide, intramuscular Thiazinamium and intramuscular atropine were associated with 'extremely frequent side-effects’. Notable tachycardia occurred shortly after intramuscular injection of Thiazinamium in two trials. Dry mouth was reported as ‘frequent’ with oral Thiazinamium, and micturition problems of moderate severity affected 13% of patients.