LYCOS RETRIEVER 
Clonidine
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Clonidine is a centrally-acting α-adrenergic receptor agonist with more affinity for α2 than α1. It selectively stimulates receptors in the brain that monitor catecholamine levels in the blood. These receptors close a negative feedback loop that begins with descending sympathetic nerves from the brain that control the production of catecholamines (epinephrine... known as adrenaline, and norepinephrine) in the adrenal medulla. By fooling the brain into believing that catecholamine levels are higher than they really are, clonidine causes the brain to reduce its signals to the adrenal medulla, which in turn lowers catecholamine production and blood levels. The result is a lowered heart rate and blood pressure, with side effects of dry mouth and fatigue. If clonidine is suddenly withdrawn the sympathetic nervous system will revert to producing high levels of epinephrine and norepinephrine, higher even than before treatment, causing rebound hypertension.
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Clonidine is in the FDA pregnancy category C. This means that it is not known whether clonidine will harm an unborn baby. Do not take this medication without first talking to your doctor if you are pregnant. Clonidine passes into breast milk. It is not known whether clonidine will harm a nursing infant. Do not take clonidine without first talking to your doctor if you are breast-feeding a baby. If you are over 60 years of age, you may be more likely to experience side effects from clonidine therapy.
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Clonidine is known to have motoric and sedative effects that could influence performance in the conditioned place aversion and conditioned suppression of responding models of opiate withdrawal. To understand the dose-effect profile and time course of this effect of clonidine and to guide design of subsequent studies with these parameters in mind, locomotor activity was assessed in standard photocell activity cages.
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Clonidine acts relatively rapidly. The patient's blood pressure declines within 30 to 60 minutes after an oral dose, the maximum decrease occurring within 2 to 4 hours. The plasma level of Clonidine peaks in approximately 3 to 5 hours and the plasma half- life ranges from 12 to 16 hours. The half-life increases up to 41 hours in patients with severe impairment of renal function. Following oral administration about 40-60% of the absorbed dose is recovered in the urine as unchanged drug in 24 hours. About 50% of the absorbed dose is metabolized in the liver.
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Clonidine stimulates alpha-adrenoreceptors in the brain stem. This action results in reduced sympathetic outflow from the central nervous system and in decreases in peripheral resistance, renal vascular resistance, heart rate, and blood pressure. CATAPRES tablets act relatively rapidly. The patient's blood pressure declines within 30 to 60 minutes after an oral dose, the maximum decrease occurring within 2 to 4 hours. Renal blood flow and glomerular filtration rate remain essentially unchanged. Normal postural reflexes are intact; therefore, orthostatic symptoms are mild and infrequent.
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Clonidine (Catapres®) was originally developed as a medicine to treat high blood pressure. Subsequently, it was found to be useful for treating childhood behavioral disorders, including attention deficit disorder (ADD), attention deficit hyperactivity disorder (ADHD), and tics. Although clonidine is not always as effective for treating tics as are the neuroleptics, the side effects of clonidine are much less serious. Therefore, this medication is often attempted first. Clonidine is available as pills or a patch for a more continuous administration through the skin. The major side effects are drowsiness and dizziness, and in some children, it may cause a drop in blood pressure.
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Clonidine