Clemizole is a drug in clinical development for the treatment of hepatitis C virus (HCV) infection. Clemizole is a novel inhibitor of TRPC5 channels. Clemizole is an H1 antagonist. Clemizole, an antihistamine drug that was once widely used for treatment of allergic disease, was recently discovered to be a potent inhibitor (IC50, 24 nM) of the interaction between an HCV protein (NS4B) and HCV RNA. Although clemizole was widely used during the 1950s and 1960s, this was before contemporary regulatory requirements were established for new drug development, and there is very minimal information about its pharmacokinetics and metabolism.

Trimeprazine (also known as Alimemazine), a phenothiazine used as antipsychotic drug. This drug is used in Russia under brand name TERALIGEN and has anti-histamine, sedative, and anti-emetic (anti-nausea) effects. Teraligen is used to treat neurosis, depression and anxiety of different origins. It prevents and relieves allergic conditions, which cause pruritus and urticaria by blocking histamine produced by the body during an allergic reaction. Trimeprazine competes with free histamine for binding at HA-receptor sites. This antagonizes the effects of histamine on HA-receptors, leading to a reduction of the negative symptoms brought on by histamine HA-receptor binding. Trimeprazine is not approved for use in humans in the United States. Nevertheless, combination of alimemazine and prednisolone (commonly sold under the brand name Temaril-P) is licensed as an antipruritic and antitussive in dogs.

Chlorphenoxamine is an antihistamine and anticholinergic used as an antipruritic and was formerly used in the sympathomimetic treatment of parkinsonism. Histamine receptor H1 antagonist. Chlorphenoxamine is used to treat Allergic conditions, it is reported as an ingredient of Systral in Germany, Malta, Portugal, Thailand, Turkey.

CAPTODIAME, also known as captodiamine, is a diphenylmethane derivative. It is a 5-HT2c receptor antagonist and agonist at sigma-1 and D3 dopamine receptors. It is an antihistamine which is used as a sedative and anxiolytic. CAPTODIAME is probably useful in preventing benzodiazepine withdrawal syndrome.

Thenalidine is an antihistamine with anticholinergic properties used as an antipruritic drug. It was withdrawn from the US, Canadian, and UK markets due to a risk of neutropenia. Thenalidine is an antagonist of the H1-receptor.

Buclizine, a piperazine derivative, is a sedating antihistamine with antimuscarinic and moderate sedative action. The drug is used mainly for its antiemetic action, particularly in the prevention of motion sickness, and in the treatment of migraine in combination with analgesics. The following side/adverse effects have been selected on the basis of their potential clinical significance: drowsiness; Incidence less frequent; blurred vision; dryness of mouth, nose, and throat; headache; nervousness, restlessness, or trouble in sleeping; upset stomach. The following drug interactions have been selected on the basis of their potential clinical significance: alcohol; anticholinergics or other medications with anticholinergic activity; apomorphine.

Diphenylpyraline is an antihistamine that prevents but does not reverse, responses mediated by histamine alone. Diphenylpyraline antagonizes most of the pharmacological effects of histamine, including urticaria and pruritus. Also, diphenylpyraline may exhibit anticholinergic actions (as do most of the antihistamines) and may thus provide a drying effect on the nasal mucosa. Antihistamines such as diphenylpyraline used in the treatment of allergy act by competing with histamine for H1-receptor sites on effector cells. This reduces the effects of histamine, leading to a temporary reduction of allergy symptoms.

Phenyltoloxamine is an ethanolamine derivative with antihistaminic property, which is used in combination with some analgesics for the temporary relief of minor aches and pains associated with headache; backache; muscular aches; temporarily reduces fever and some others disorders. Phenyltoloxamine blocks H1 histamine receptor, thereby inhibiting phospholipase A2 and production of endothelium-derived relaxing factor, nitric oxide. Subsequent lack of activation of guanylyl cyclase through nitric oxide results in decreased cyclic GMP levels, thereby inhibiting smooth muscle constriction of various tissues, decreasing capillary permeability and decreasing other histamine-activated allergic reactions.

PYRROBUTAMINE is a potent H1-antihistamine. H1-antihistamines interfere with the agonist action of histamine at the H1 receptor and are administered to attenuate the inflammatory process in order to treat conditions such as allergic rhinitis, allergic conjunctivitis, and urticaria.

Bromodiphenhydramine also known as bromazine, is an antihistamine and anticholinergic agent, which was used to under brand name ambordyl. Ambordyfor was indicated for the treatment of allergic symptoms, but that usage, was discontinued. It was shown, that bromodiphenhydramine competed with free histamine for binding at HA-receptor sites and lead to a reduction of the negative symptoms brought on by histamine HA-receptor binding.