Benztropine is an anticholinergic used in the symptomatic treatment of all etiologic groups of parkinsonism and drug-induced extrapyramidal reactions (except tardive dyskinesia). Benztropine possesses both anticholinergic and antihistaminic effects, although only the former has been established as therapeutically significant in the management of parkinsonism. Benztropine's anticholinergic activity is about equal to that of atropine. Benztropine also inhibits dopamine reuptake via the dopamine transporter at nerve terminals. Benztropine is a selective M1 muscarinic acetylcholine receptor antagonist. It is able to discriminate between the M1 (cortical or neuronal) and the peripheral muscarinic subtypes (cardiac and glandular). Benztropine partially blocks cholinergic activity in the CNS, which is responsible for the symptoms of Parkinson's disease. It is also thought to increase the availability of dopamine, a brain chemical that is critical in the initiation and smooth control of voluntary muscle movement. Used as an adjunct in the therapy of all forms of parkinsonism and also for use in the control of extrapyramidal disorders due to neuroleptic drugs.

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.

Clioquinol is a broad-spectrum antibacterial with antifungal properties, bacteriostatic. It is used as an antifungal and antiprotozoal topical drug OTC product for treatment of human infections. Previousely was used for wide number of intestinal disorders including lambliasis, shigellosis, balantidiral dysentery and some forms of diarrheas. The physiologic effect of clioquinol is by increased histamine release and cell-mediated immunity. It is a member of a family hydroxyquinolines which inhibit certain enzymes related to DNA replication. It is a copper, iron and zink chelating agent. It is an organic molecule with a quinolinic acid as its apparent core which itself is a neurotransmitter. In large doses it possesses neurotoxicity and may induce neurological disease such as subacute myelo-optic neuropathy by creating copper deficiency that leads to zink excess. SMON (Sub-Acute-Myelo-Optical-Neuropathy) - a polio-like disease began as an epidemic in 1959 in Japan was believed to be a Clioquinol caused. Clioquinol is a standardized chemical allergen. It has been resurrected as a potential treatment for Alzheimer's disease since it perturbs metallo-chemistry of amyloid and clioquinol treatment has been shown to be beneficial in a mouse model of Alzheimer's disease.

DEXBROMPHENIRAMINE is an alkylamine derivative with anticholinergic and sedative properties. It is a histamine H1-receptor antagonist that competes with histamine for the H1-receptor sites on effector cells in the gastrointestinal tract, blood vessels, and respiratory tract. The antagonistic action of this agent blocks the activities of endogenous histamine, which subsequently leads to temporary relief from the negative histamine-mediated symptoms of an allergic reaction such as bronchoconstriction, vasodilation, increased capillary permeability and spasmodic contractions of the gastrointestinal smooth muscle. DEXBROMPHENIRAMINE as a part of combination medicine is used to treat symptoms of the common cold or seasonal allergies, including sneezing, runny or stuffy nose, and itchy, watery eyes.

Xylometazoline, also spelled xylomethazoline, is a medication which is used to improve symptoms of nasal congestion, allergic rhinitis, and sinusitis. Xylometazoline was patented in 1956 and came into medical use in 1959. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. The drug works by stimulating adrenergic receptors on the lamina propria of blood vessels in the nose. The decongestant effect is due to constriction of large veins in the nose which swell up during the inflammation of any infection or allergy of the nose. The smaller arteries are also constricted and this causes the colour of the nasal epithelium to be visibly paler after dosage. The standard adult solution strength is 0.1% w/v xylometazoline (or 1 mg per 1 mL solution), and the dose for children under 12 is usually 0.05% (0.5 mg/mL).

Triprolidine is a first generation histamine H1 antagonist, which in combination with codeine phosphate and pseudoephedrine hydrochloride is sold under brand name TRIACIN-C. TRIACIN-C is indicated for temporary relief of coughs and upper respiratory symptoms, including nasal congestion, associated with allergy or the common cold.

Dexchlorpheniramine, the d-isomer of the racemic compound chlorpheniramine, is two times more active than chlorpheniramine. Dexchlorpheniramine does not prevent the release of histamine, but rather, competes with free histamine for binding at the H1-receptor sites, and competitively antagonizes the effects of histamine on H1-receptors in the GI tract, uterus, large blood vessels, and bronchial muscle. Blockade of H1-receptors also suppresses the formation of oedema, flare, and pruritus that result from histaminic activity. Since dexchlorpheniramine binds to central and peripheral H1-receptors, sedative effects are likely to occur. H1-antagonists are structurally similar to anticholinergic agents and therefore possess the potential to exhibit anticholinergic properties of varying degrees. They also have antipruritic effects. Dexchlorpheniramine has high antihistaminic activity, moderate anticholinergic effects and minimal sedative effects. The drug does not possess antiemetic properties.

Brompheniramine is an antihistaminergic medication of the propylamine class. It is a first-generation antihistamine, which is used for the treatment of the symptoms of the common cold and allergic rhinitis, such as runny nose, itchy eyes, watery eyes, and sneezing. In allergic reactions, an allergen interacts with and cross-links surface IgE antibodies on mast cells and basophils. Once the mast cell-antibody-antigen complex is formed, a complex series of events occurs that eventually leads to cell-degranulation and the release of histamine (and other chemical mediators) from the mast cell or basophil. Once released, histamine can react with local or widespread tissues through histamine receptors. Brompheniramine is a histamine H1 antagonist of the alkylamine class. It provides effective, temporary relief of sneezing, watery and itchy eyes, and runny nose due to hay fever and other upper respiratory allergies. Brompheniramine is metabolised by cytochrome P450s. The halogenated alkylamine antihistamines all exhibit optic isomerism and brompheniramine products contain racemic brompheniramine maleate whereas dexbrompheniramine (Drixoral) is the dextrorotary (right-handed) stereoisomer.

Meclizine, a piperazine-derivative H1-receptor antagonist similar to buclizine, cyclizine, and hydroxyzine, is used as an antivertigo/antiemetic agent. Meclizine is used in the management of nausea, vomiting, and dizziness associated with motion sickness and vertigo in diseases affecting the vestibular apparatus. Along with its actions as an antagonist at H1-receptors, meclizine also possesses anticholinergic, central nervous system depressant, and local anesthetic effects. Meclizine depresses labyrinth excitability and vestibular stimulation and may affect the medullary chemoreceptor trigger zone. It is sold under the brand names Bonine, Bonamine, Antivert, Postafen, Sea Legs, and Dramamine II.

Chlorpheniramine is an antihistamine. Chlorpheniramine 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. Chlorpheniramine is used for relieving symptoms of sinus congestion, sinus pressure, runny nose, watery eyes, itching of the nose and throat, and sneezing due to upper respiratory infections (eg, colds), allergies, and hay fever. In addition to being a histamine H1 receptor (HRH1) antagonist, chlorphenamine has been shown to work as a serotonin-norepinephrine reuptake inhibitor or SNRI.