Clonidine

Clonidine
Clinical data
Pronunciation	/ˈklɒnədiːn/
Trade names	Catapres, others
AHFS/Drugs.com	Monograph
MedlinePlus	a682243
License data	US DailyMed: Clonidine;
Pregnancy; category	AU: B3;
Routes of; administration	By mouth, epidural, intravenous, transdermal, topical
Drug class	α2A-adrenergic receptor agonist
ATC code	C02AC01 (WHO) ;
Legal status
Legal status	AU: S4 (Prescription only); CA: ℞-only; UK: POM (Prescription only); US: ℞-only;
Pharmacokinetic data
Bioavailability	70–80% (oral), 60–70% (transdermal)
Protein binding	20–40%
Metabolism	Liver to inactive metabolites, 2/3 CYP2D6
Onset of action	IR: 30–60 minutes after an oral dose
Elimination half-life	IR: 12–16 hours; 41 hours in kidney failure, 48 hours for repeated dosing
Duration of action	Blood pressure: ≤ 8 hours;
Excretion	Urine (72%)
Identifiers
	IUPAC name N-(2,6-Dichlorophenyl)-4,5--1H-imidazol-2-amine;
CAS Number	4205-90-7 ;
PubChem CID	2803;
IUPHAR/BPS	516;
DrugBank	DB00575 ;
ChemSpider	2701 ;
UNII	MN3L5RMN02;
KEGG	D00281 ;
ChEBI	CHEBI:3757 ;
ChEMBL	ChEMBL134 ;
CompTox Dashboard (EPA)	DTXSID6022846 ;
ECHA InfoCard	100.021.928
Chemical and physical data
Formula	C9H9Cl2N3
Molar mass	230.09 g·mol−1
3D model (JSmol)	Interactive image;
	SMILES Clc1cccc(Cl)c1N/C2=N/CCN2;
	InChI InChI=1S/C9H9Cl2N3/c10-6-2-1-3-7(11)8(6)14-9-12-4-5-13-9/h1-3H,4-5H2,(H2,12,13,14) ; Key:GJSURZIOUXUGAL-UHFFFAOYSA-N ;
	(verify)

Clonidine, sold under the brand name Catapres among others, is an α_2A-adrenergic receptor agonist medication used to treat high blood pressure, attention deficit hyperactivity disorder (ADHD), drug withdrawal (e.g., alcohol, opioids, or nicotine), menopausal flushing, diarrhea, spasticity, and certain pain conditions. The drug is often prescribed off-label for tics. It is used orally (by mouth), by injection, or as a transdermal skin patch. Onset of action is typically within an hour with the effects on blood pressure lasting for up to eight hours.

Common side effects include dry mouth, dizziness, headaches, hypotension, and sleepiness. Severe side effects may include hallucinations, heart arrhythmias, and confusion. If rapidly stopped, withdrawal effects may occur, such as a dangerous rise in blood pressure. Use during pregnancy or breastfeeding is not recommended. Clonidine lowers blood pressure by stimulating α₂-adrenergic receptors in the brain, which results in relaxation of many arteries.

Clonidine was patented in 1961 and came into medical use in 1966. It is available as a generic medication. In 2022, it was the 71st most commonly prescribed medication in the United States, with more than 9 million prescriptions.