Description
Chlorcyclizine Hydrochloride, often marketed under trade names such as Ahist and Histade, is a first-generation antihistamine primarily used for its anticholinergic and sedative properties. This medication is widely recognized in treating various allergic conditions, including allergic rhinitis and urticaria. It acts on H1 histamine receptors, which play a crucial role in allergic responses. Several research institutions have conducted extensive studies to understand its efficacy and safety profile. The drug was first synthesized in the 1940s and has since been a staple in allergy relief therapy. Although first-generation antihistamines are often overshadowed by second-generation counterparts due to their sedative effects, Chlorcyclizine Hydrochloride remains a valuable option for individuals seeking rapid and effective symptom relief.
Uses
An antihistaminic drug
Health Hazard
Chlorcyclizine Hydrochloride can cause developmental toxicity according to state or federal government labelling requirements.
Biological Activity
chlorcyclizine is a phenylpiperazine antagonist for histamine h1 receptor [1].the histamine has been involved in modulating many physiological functions of the hypothalamus, such as arousal state, feeding, locomotor activity, and drinking. histamine has been involved in circadian rhythm of locomotor activity and exploratory behavior through h1r [1].
Mechanism of action
The primary mechanism of action of Chlorcyclizine Hydrochloride revolves around its ability to block H1 histamine receptors. Histamine is a compound involved in local immune responses and functions as a neurotransmitter. When an allergic reaction occurs, histamine is released from mast cells and binds to H1 receptors, leading to symptoms such as itching, swelling, and vasodilation. By blocking these receptors, Chlorcyclizine Hydrochloride effectively reduces the intensity of allergic symptoms. In addition to its antihistaminic activity, Chlorcyclizine Hydrochloride exhibits anticholinergic properties by blocking muscarinic acetylcholine receptors. This dual action can help in reducing secretions and providing sedation, which is beneficial in treating symptoms like runny nose and watery eyes. The sedative effect is due to its ability to cross the blood-brain barrier and act on central histamine and acetylcholine receptors, making it particularly useful for conditions requiring sedation, such as insomnia caused by allergic reactions.
Safety Profile
Poison by ingestion,
subcutaneous, intravenous, and
intraperitoneal routes. An experimental
teratogen. Other experimental reproductive
effects. When heated to decomposition it
emits very toxic fumes of HCl and NOx.
in vitro
the ki value of chlorcyclizine for histamine h1 receptor was 9 nm [1]. chlorcyclizin was effective against hepatitis c virus (hcv) with an ec50 of 44 nm, preventing viral entry into host cells [2].
in vivo
in chimeric mice xenografted with primary human hepatocytes, chlorcyclizine (10-50 mg/kg) significantly inhibited infection of hcv genotypes 1b and 2a [2]. chlorcyclizine induced a resistance to sodium pentobarbital anesthesia. intraperitoneal injection of chlorcyclizine showed a sedative effect in small doses, but a convulsive effect in large doses. intraperitoneal injections of the drug did not affect the recovery time from pentobarbital anesthesia [3]. in rats, pretreatment with chlorcyclizine for several days shortened the duration of action of a subsequent dose of hexobarbital, pentobarbital or zoxazolamine, and accelerated in vivo metabolism of hexobarbital [4]. the administration of chlorcyclizine (50 g/kg) to rats by stomach tube daily for 1 week resulted in significant increases in liver weight, microsomal protein concentration and the activity of the nadph-dependent hepatic microsomal ethanol-oxidizing system (meos) [5].
References
[1] tran v t, chang r s, snyder s h. histamine h1 receptors identified in mammalian brain membranes with [3h] mepyramine[j]. proceedings of the national academy of sciences, 1978, 75(12): 6290-6294.
[2] he, s. ,xiao, j.,dulcey, a.e., et al. discovery, optimization, and characterization of novel chlorcyclizine derivatives for the treatment of hepatitis c virus infection. journal of medicinal chemistry 59(3), 841-853 (2016).
[3] thompson i d, dolowy w c, cole w h. development of a resistance to sodium pentobarbital in rats fed on a diet containing chlorcyclizine hydrochloride[j]. journal of pharmacology and experimental therapeutics, 1959, 127(2): 164-166.
[4] conney a h, burns j j, michaelson i a. stimulatory effect of chlorcyclizine on barbiturate metabolism[j]. journal of pharmacology and experimental therapeutics, 1961, 132(2): 202-206.
[5] khanna j m, kalant h, lin g. significance in vivo of the increase in micro-somal ethanol-oxidizing system after chronic administration of ethanol, pheno-barbital and chlorcyclizine[j]. biochemical pharmacology, 1972, 21(16): 2215-2226.
