Clinical data | |
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Pronunciation | /ˈklɒnədiːn/ |
Trade names | Catapres, Kapvay, Nexiclon, others |
AHFS/Drugs.com | Monograph |
MedlinePlus | a682243 |
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Routes of administration | Oral, epidural, intravenous (IV), transdermal, topical |
Drug class | Centrally acting α2A-agonist hypotensive agent |
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Pharmacokinetic data | |
Bioavailability | 70–80% (oral),[2][3] 60–70% (transdermal)[4] |
Protein binding | 20–40%[5] |
Metabolism | Liver to inactive metabolites,[5] 2/3 CYP2D6[9] |
Onset of action | IR: 30–60 minutes after an oral dose[6] |
Elimination half-life | IR: 12–16 hours; 41 hours in kidney failure,[7][8] 48 hours for repeated dosing[4] |
Excretion | Urine (72%)[5] |
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ECHA InfoCard | 100.021.928 |
Chemical and physical data | |
Formula | C9H9Cl2N3 |
Molar mass | 230.09 g·mol−1 |
3D model (JSmol) | |
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Clonidine, sold under the brand name Catapres among others, is an α2A-adrenergic agonist[10] medication used to treat high blood pressure, ADHD, drug withdrawal (alcohol, opioids, or nicotine), menopausal flushing, diarrhea, spasticity, and certain pain conditions.[11] The drug is often prescribed off-label for tics. It is used orally (by mouth), by injection, or as a transdermal skin patch.[11] Onset of action is typically within an hour with the effects on blood pressure lasting for up to eight hours.[11]
Common side effects include dry mouth, dizziness, headaches, hypotension, and sleepiness.[11] Severe side effects may include hallucinations, heart arrhythmias, and confusion.[12] If rapidly stopped, withdrawal effects may occur, such as a dangerous rise in blood pressure.[11] Use during pregnancy or breastfeeding is not recommended.[12] Clonidine lowers blood pressure by stimulating α2 receptors in the brain, which results in relaxation of many arteries.[11]
Clonidine was patented in 1961 and came into medical use in 1966.[13][14][15] It is available as a generic medication.[11] In 2021, it was the 80th most commonly prescribed medication in the United States, with more than 8 million prescriptions.[16][17]
davies
was invoked but never defined (see the help page).The pharmacokinetics of clonidine is dose-proportional in the range of 100 to 600 µg.The absolute bioavailability of clonidine on oral administration is 70% to 80%. Peak plasma clonidine levels are attained in approximately 1 to 3 hours.
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.
Following intravenous administration, clonidine displays biphasic disposition with a distribution half-life of about 20 minutes and an elimination half-life ranging from 12 to 16 hours. The half-life increases up to 41 hours in patients with severe impairment of renal function. Clonidine crosses the placental barrier. It has been shown to cross the blood–brain barrier in rats.