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AHFS/Drugs.com | Monograph |
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ECHA InfoCard | 100.016.220 |
Chemical and physical data | |
Formula | C18H20N2S |
Molar mass | 296.43 g·mol−1 |
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Methdilazine (Dilosyn, Tacaryl) is a first-generation antihistamine with anticholinergic properties of the phenothiazine class.
Phenothiazine, abbreviated PTZ, is an organic compound that has the formula S(C6H4)2NH and is related to the thiazine-class of heterocyclic compounds. Derivatives of phenothiazine are highly bioactive and have widespread use and rich history. The derivatives chlorpromazine and promethazine revolutionized the fields of psychiatry and allergy treatment, respectively. An earlier derivative, methylene blue, was one of the first antimalarial drugs, and derivatives are under investigation as possible anti-infective drugs. Phenothiazine is a prototypical pharmaceutical lead structure in medicinal chemistry.
Chlorpromazine (CPZ), marketed under the brand names Thorazine and Largactil among others, is an antipsychotic medication. It is primarily used to treat psychotic disorders such as schizophrenia. Other uses include the treatment of bipolar disorder, severe behavioral problems in children including those with attention deficit hyperactivity disorder, nausea and vomiting, anxiety before surgery, and hiccups that do not improve following other measures. It can be given by mouth, by injection into a muscle, or into a vein.
Perphenazine is a typical antipsychotic drug. Chemically, it is classified as a piperazinyl phenothiazine. Originally marketed in the United States as Trilafon, it has been in clinical use for decades.
H1 antagonists, also called H1 blockers, are a class of medications that block the action of histamine at the H1 receptor, helping to relieve allergic reactions. Agents where the main therapeutic effect is mediated by negative modulation of histamine receptors are termed antihistamines; other agents may have antihistaminergic action but are not true antihistamines.
Diphenhydramine is an antihistamine medication mainly used to treat allergies. It can also be used for insomnia, symptoms of the common cold, tremor in parkinsonism, and nausea. It is taken by mouth, injected into a vein, injected into a muscle, or applied to the skin. Maximal effect is typically around two hours after a dose, and effects can last for up to seven hours.
Hydroxyzine, sold under the brand names Atarax and others, is an antihistamine medication. It is used in the treatment of itchiness, anxiety, and nausea, including that due to motion sickness. It is used either by mouth or injection into a muscle.
Hives, also known as urticaria, is a kind of skin rash with red, raised, itchy bumps. They may also burn or sting. Often the patches of rash move around. Typically they last a few days and do not leave any long-lasting skin changes. Fewer than 5% of cases last for more than six weeks. The condition frequently recurs.
Cetirizine, sold under the brand name Zyrtec among others, is a second-generation antihistamine used to treat allergic rhinitis, dermatitis, and urticaria (hives). It is taken by mouth. Effects generally begin within an hour and last for about a day. The degree of benefit is similar to other antihistamines such as diphenhydramine.
Doxepin is a medication used to treat major depressive disorder, anxiety disorders, chronic hives, and trouble sleeping. For hives it is a less preferred alternative to antihistamines. It has a mild to moderate benefit for sleeping problems. It is used as a cream for itchiness due to atopic dermatitis or lichen simplex chronicus.
Fluacizine, sold under the brand name Phtorazisin, is a tricyclic antidepressant (TCA) of the phenothiazine group which is or was marketed in Russia. Unlike other phenothiazines, fluacizine is not an antipsychotic, and can actually reverse catalepsy and extrapyramidal symptoms induced by antidopaminergic agents like antipsychotics, reserpine, and tetrabenazine as well as potentiate amphetamine-induced stereotypy. It is known to act as a norepinephrine reuptake inhibitor, antihistamine, and anticholinergic. The drug was developed in the 1960s and was marketed in the 1970s. It is the trifluoromethyl analogue of chloracizine.
Histidine decarboxylase (HDC) is an enzyme responsible for catalyzing the decarboxylation of histidine to form histamine. In mammals, histamine is an important biogenic amine with regulatory roles in neurotransmission, gastric acid secretion and immune response. Histidine decarboxylase is the sole member of the histamine synthesis pathway, producing histamine in a one-step reaction. Histamine cannot be generated by any other known enzyme. HDC is therefore the primary source of histamine in most mammals and eukaryotes. The enzyme employs a pyridoxal 5'-phosphate (PLP) cofactor, in similarity to many amino acid decarboxylases. Eukaryotes, as well as gram-negative bacteria share a common HDC, while gram-positive bacteria employ an evolutionarily unrelated pyruvoyl-dependent HDC. In humans, histidine decarboxylase is encoded by the HDC gene.
Cyproheptadine, sold under the brand name Periactin among others, is a first-generation antihistamine with additional anticholinergic, antiserotonergic, and local anesthetic properties.
Chlorcyclizine is a first-generation antihistamine of the diphenylmethylpiperazine group marketed in the United States and certain other countries. It is used primarily to treat allergy symptoms such as rhinitis, urticaria, and pruritus, and may also be used as an antiemetic. In addition to its antihistamine effects, chlorcyclizine also has some anticholinergic, antiserotonergic, and local anesthetic properties. It also has been studied as a potential treatment for various flaviviruses like Hepatitis C and Zika Virus.
Tripelennamine, sold under the brand name Pyribenzamine by Novartis, is a drug that is used as an antipruritic and first-generation antihistamine. It can be used in the treatment of asthma, hay fever, rhinitis, and urticaria, but is now less common as it has been replaced by newer antihistamines. The drug was patented at CIBA, which merged with Geigy into Ciba-Geigy, and eventually becoming Novartis.
Tricyclics are chemical compounds that contain three interconnected rings of atoms.
Niaprazine (INN) is a sedative-hypnotic drug of the phenylpiperazine group. It has been used in the treatment of sleep disturbances since the early 1970s in several European countries including France, Italy, and Luxembourg. It is commonly used with children and adolescents on account of its favorable safety and tolerability profile and lack of abuse potential.
Metopimazine, sold under the brand names Nortrip, Vogalen, and Vogalene, is an antiemetic of the phenothiazine group which is used to treat nausea and vomiting. It is marketed in Europe, Canada, and South America. As of August 2020, metopimazine has been repurposed and is additionally under development for use in the United States for the treatment of gastroparesis.
Antihistamines are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. Typically, people take antihistamines as an inexpensive, not patented (generic), drug that can be bought without a prescription and relieves from nasal congestion, sneezing, or hives caused by pollen, dust mites, or animal allergy with few side effects. Antihistamines are usually for short-term treatment. Chronic allergies increase the risk of health problems which antihistamines might not treat, including asthma, sinusitis, and lower respiratory tract infection. Consultation of a medical professional is recommended for those who intend to take antihistamines for longer-term use.
Oxyfedrine is a vasodilator and a β adrenoreceptor agonist. It was found to depress the tonicity of coronary vessels, improve myocardial metabolism and also exert a positive chronotropic and inotropic effects, thereby not precipitating angina pectoris. The latter property is particularly important, because other vasodilators used in angina may be counter productive causing coronary steal phenomenon.
JNJ-7777120 was a drug being developed by Johnson & Johnson Pharmaceutical Research & Development which acts as a potent and selective antagonist at the histamine H4 receptor. It has anti-inflammatory effects, and has been demonstrated to be superior to traditional (H1) antihistamines in the treatment of pruritus (itching). The drug was abandoned because of its short in vivo half-life and hypoadrenocorticism toxicity in rats and dogs, that prevented advancing it into clinical studies.
The ring-contracted analog, methdilazine shows only very weak activity as a tranquilizer; instead, that agent constitutes an important antihistamine.