Clonidine hydrochloride

Chemical properties

White Solid

Originator

Catapresan,Boehringer,Ingelheim,1966

The Uses of Clonidine hydrochloride

Clonidine hydrochloride tablets are indicated in the treatment of hypertension. It has found new uses, including treatment of some types of neuropathic pain, opioid detoxification, sleep hyperhidrosis, anaesthetic use, and off-label, to counter the side effects of stimulant medications such as methylphenidate or amphetamine. It is becoming a more accepted treatment for insomnia, as well as for relief of menopausal symptoms. Clonidine(4205-91-8) is increasingly used in conjunction with stimulants to treat attention-deficit hyperactivity disorder (ADHD).

The Uses of Clonidine hydrochloride

Labelled Clonidine. α2-Adrenergic agonist. Antihypertensive; analgesic for neuropathic pain.

The Uses of Clonidine hydrochloride

`a2-adrenoceptor agonist, imidazoline receptor ligand, anti-hypertensive

The Uses of Clonidine hydrochloride

In shaving soaps.

What are the applications of Application

Clonidine hydrochloride is an antihypertensive α2-adrenergic receptor agonist

Definition

ChEBI: Clonidine hydrochloride is a dichlorobenzene.

Manufacturing Process

N-(2,6-dichlorophenyl)thiourea (MP 149°C) was prepared in customary manner from 2,6-dichloroaniline (Organic Synthesis III, 262-263) and ammonium thiocyanate. 16.0 g of this thiourea derivative were refluxed for
2.5 hours together with 16 g of methyl iodide in 150 cc of methanol. Thereafter, the methanol was evaporated out of the reaction mixture in vacuo, leaving as a residue 22 g of N-(2,6-dichlorophenyl)-S-methyl-isothiouronium hydroiodide of the formula having a melting point of 170°C. The entire residue was then admixed with an excess (120%) above the molar equivalent of ethylenediamine, and the mixture was heated for about one hour at 130° to 150°C. Methyl mercaptan was given off. Thereafter, the reaction mixture comprising 2-(2',6'-dichloroanilino)-1,3-diazacyclopentene-(2) hydroiodide was taken up in hot dilute acetic acid, and the resulting solution was made alkaline with 2 N NaOH. A precipitate formed which was separated by vacuum filtration, washed with water and dried. 4.0 g of 2-(2',6'-dichloroanilino)-1,3- diazacyclopentene-(2) were obtained. The product had a melting point of 130°C.
The free base was then dissolved in absolute methanol, and the resulting solution was then adjusted to an acid pH value with an ethereal hydrochloric acid solution. The acidified solution was purified with charcoal and then dry ether was added thereto until crystallization took place. The hydrochloride, prepared in this customary manner, had a melting point of 305°C according to US Patent 3,202,660

brand name

Catapres (Boehrin- ger Ingelheim); Duraclon (Xanodyne).

Therapeutic Function

Antihypertensive

Synthesis Reference(s)

Synthesis, p. 64, 1987 DOI: 10.1055/s-1987-27847

General Description

Clonidine hydrochloride, 2-[(2,6-dichlorophenyl)imino]imidazolidine monohydrochloride(Catapres), was the first antihypertensive known to acton the CNS. It was synthesized in 1962 as a derivativeof the known -sympathomimetic drugs naphazoline andtolazoline, potential nasal vasoconstrictors, but instead itproved to be effective in the treatment of mild-to-severe hypertension.Clonidine hydrochloride acts by both peripheral andcentral mechanisms in the body to affect blood pressure. Itstimulates the peripheral -adrenergic receptors to producevasoconstriction, resulting in a brief period of hypertension.

Biological Activity

Prototypical I 1 imidazoline receptor ligand. α 2 -adrenergic receptor agonist. Antihypertensive.

Biochem/physiol Actions

Clonidine hydrochloride is used for management of hypertension in pregnant women. In addition, it also acts as a therapeutic for neonatal abstinence syndrome. Clonidine hydrochloride binds to central α-adrenergic receptors and reduces the efferent sympathetic neuronal vasoconstrictor tone to the heart, kidneys and peripheral vasculature leading to vasodilatation and reduction in the blood pressure.

Clinical Use

Clonidine hydrochloride acts by both peripheral andcentral mechanisms in the body to affect blood pressure. Itstimulates the peripheral α-adrenergic receptors to producevasoconstriction, resulting in a brief period of hypertension.Clonidine hydrochloride acts centrally to inhibitthe sympathetic tone and cause hypotension that is ofmuch longer duration than the initial hypertensive effect.Administration of clonidine hydrochloride thus produces abiphasic change in blood pressure, beginning with a briefhypertensive effect and followed by a hypotensive effectthat persists for about 4 hours. This biphasic response isaltered by dose only. Larger doses produce a greater hypertensiveeffect and delay the onset of the hypotensiveproperties of the drug. Clonidine hydrochloride acts on 2-adrenoreceptors located in the hindbrain to produce itshypotensive action. Clonidine hydrochloride also acts centrallyto cause bradycardia and to reduce plasma levels ofrenin. Sensitization of baroreceptor pathways in the CNSappears to be responsible for the bradycardia transmittedby way of the vagus nerve. The central mechanism that resultsin decreased plasma renin is not known, however.The hypotensive properties of clonidine in animals can beblocked by applying -adrenergic blocking agents directlyto the brain.

Drug interactions

Potentially hazardous interactions with other drugs
Antidepressants: tricyclics antagonise hypotensive effect and also increase risk of hypertension on clonidine withdrawal; increased hypotensive effect with MAOIs; hypotensive effect possibly antagonised by mirtazapine.
Beta-adrenoreceptor antagonists: increased risk of hypertension on withdrawal.
Ciclosporin: may increase ciclosporin levels.
Sympathomimetics: possibly increased risk of hypertension with adrenaline and noradrenaline; serious adverse effects reported with methylphenidate.

Metabolism

About 50% of a of clonidine dose is metabolised in the liver.
It is excreted in the urine as unchanged drug and metabolites, 40-60% of an oral dose being excreted in 24 hours as unchanged drug; about 20% of a dose is excreted in the faeces, probably via enterohepatic circulation.

storage

Store at RT

Purification Methods

This antihypertensive is recrystallised from EtOH/Et2O and dried in a vacuum (solubility in H2O is 5%). The free base has m 124-125o and is recrystallised from hexane. [Jen et al. J Med Chem 18 90 1975, NMR: Jackman & Jen J Am Chem Soc 97 2811 1975.]