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).
일반 설명
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.
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.
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.]
