Clemastine is an antihistamine with anticholinergic (drying) and sedative side effects. Clemastine is a selective histamine H1 antagonist and binds to the histamine H1 receptor. This blocks the action of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms brought on by histamine. It is used for the relief of symptoms associated with allergic rhinitis such as sneezing, rhinorrhea, pruritus and acrimation. Also for the management of mild, uncomplicated allergic skin manifestations of urticaria and angioedema. Used as self-medication for temporary relief of symptoms associated with the common cold.

Glutodine (Cyproheptadine), sold under the brand name Periactin or Peritol, is a first-generation antihistamine with additional antiserotonergic, anticholinergic and local anesthetic properties. Glutodine is a white to slightly yellowish crystalline solid, which is soluble in water, freely soluble in methanol, sparingly soluble in ethanol, soluble in chloroform, and practically insoluble in ether. Cyproheptadine is used to treat allergic reactions (specifically hay fever), Vasomotor rhinitis, Allergic conjunctivitis due to inhalant allergens and foods, uncomplicated allergic skin manifestations of urticaria and angioedema amelioration of allergic reactions to blood or plasma, Cold urticaria, and Dermatographism. Cyproheptadine is used off-label to treat Spasticity Associated With Spinal Cord, Migraine Headache Prophylaxis, Decreased Appetite Secondary to Chronic Disease, Drug-Induced Sexual Dysfunction, Serotonin Syndrome.

Carbinoxamine is a histamine-H1 receptor blocking agent. It is an antihistamine with anticholinergic (drying) and sedative properties. Carbinoxamine appears to compete with histamine (type H1) for receptor sites on effector cells in the gastrointestinal tract, blood vessels and respiratory tract. Carbinoxamine is effective for the symptomatic treatment of seasonal and perennial allergic rhinitis; vasomotor rhinitis; allergic conjunctivitis due to inhalant allergens and foods; mild, uncomplicated allergic skin manifestations of urticaria and angioedema; dermatographism; as therapy for anaphylactic reactions adjunctive to epinephrine and other standard measures after the acute manifestations have been controlled. Most common adverse reactions are: sedation, sleepiness, dizziness, disturbed coordination, epigastric distress, and thickening of bronchial secretions. Avoid concomitant use of alcohol and CNS depressants (hypnotics sedatives, tranquilizers, etc.) due to additive adverse effects.

Cidoxepin is the cis-isomer of the widely prescribed tricyclic compound doxepin. Commercial preparations of the tricyclic anti-depressant doxepin contain 15% of the more active cis-doxepin and 85% of the trans-isomer. Elorac, Inc., a rapidly growing specialty pharmaceutical company focused on the treatment of dermatological disorders, is pleased to announce that it has acquired worldwide rights to the active agent Cidoxepin from Gideon Pharmaceuticals. Cidoxepin appears to be much more potent than doxepin while having less sedative and cholinergic side effects. Elorac plans to develop oral formulations of the drug to treat urticaria and topical formulations for treatment of atopic and contact dermatitis.

AZD-1981, developed by AstraZeneca, is a potent (binding IC50 of 4nM), fully reversible, functionally non-competitive antagonist of human CRTh2. It blocks agonist-induced human eosinophil CD11b expression, shape change (including in whole blood), and chemotaxis as well as an basophil shape change and Th2-cell chemotaxis at IC50's of 8.5-50nM. Potency is similar across species as is plasma protein binding (~97%). AZD-1981 is a weak (10s of μM) inhibitor in vitro of CYP2C9, OATP1B1 and UGT1A1 as well as an inducer of CYP3A4. AZD-1981 was well tolerated and no safety concerns were identified.There was no beneficial clinical effect of AZD-1981, at a dose of 1000 mg twice daily for 4 weeks, in patients with moderate to severe COPD. AZD-1981 has being discontinued for asthma and chronic obstructive pulmonary disease. AstraZeneca is collaborating with Johns Hopkins University for the development of AZD-1981 in the treatment of chronic idiopathic urticaria. It is in phase II clinicals studies for the treatment of Urticaria.

Dimetindene (trade name Fenistil; other name dimethindene maleate) is a potent antipruritic antihistamine, characterized by the small size of its effective dose and its rapidity of action. Dimetindene is an antihistamine/anticholinergic that is a selective H1 antagonist. Its effect sets in after 20 to 60 minutes and lasts several hours. Dimetindene drops as well as Dimetindene syrup is particularly indicated in pediatric practice. Dimetindene is indicated as symptomatic treatment of allergic reactions: urticaria, allergies of the upper respiratory tract such as hay fever and perennial rhinitis, food, and drug allergies; pruritus of various origins, except pruritus due to cholestasis; insect bites. Dimetindene is also indicated for pruritus in eruptive skin diseases such as chicken-pox. Dimetindene can be as an adjuvant in eczema and other pruriginous dermatoses of allergic origin.

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.

Homochlorcyclizine (INN) is an antihistamine which has been marketed in Japan since 1965. It is used in the treatment of Itching sensation resulting from skin diseases (eczema or dermatitis, pruritus, drug eruption, toxic erythema and infant strophulus), urticaria and allergic rhinitis. Homochlorcyclizine hydrochloride possesses several pharmacological properties: 1) inhibits bradykinin-induced contractions of isolated guinea pig ileum; 2)partially blocks SRS-A (slow-reacting substance of anaphylaxis )- induced contractions in isolated guinea pig il eum. 3) Homochlorcyclizine hydrochloride completely inhibits histamine-induced contractions at a concentration of 0.1μg/mL, while it completely inhibits serotonin or acetylcholine- induced contractions at a concentration of 1μg/mL.

Dimethindene (+)- is one of Dimethindene enantiomer that is a subtype-selective M2 muscarinic receptor antagonist. Dimetindene (trade name Fenistil; other name dimethindene maleate) is a potent antipruritic antihistamine, characterized by the small size of its effective dose and its rapidity of action. Dimetindene is an antihistamine/anticholinergic that is a selective H1 antagonist. Its effect sets in after 20 to 60 minutes and lasts several hours. Dimetindene drops as well as Dimetindene syrup is particularly indicated in pediatric practice. Dimetindene is indicated as symptomatic treatment of allergic reactions: urticaria, allergies of the upper respiratory tract such as hay fever and perennial rhinitis, food, and drug allergies; pruritus of various origins, except pruritus due to cholestasis; insect bites. Dimetindene is also indicated for pruritus in eruptive skin diseases such as chickenpox. Dimetindene can be as an adjuvant in eczema and other pruriginous dermatoses of allergic origin.

Mebhydrolin (INN) or mebhydroline is a histamine H1-receptor antagonist. It is not available in the United States, but it is available in various other countries under the brand names Bexidal and Diazolin. It is used for symptomatic relief of allergic symptoms caused by histamine release, including nasal allergies and allergic dermatosis.