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Identification
NameLofexidine
Accession NumberDB04948
TypeSmall Molecule
GroupsApproved, Investigational
Description

Lofexidine is an alpha2-adrenergic receptor agonist. It can be used as a short acting anti-hypertensive, but is mostly used to help relieve symptoms of heroin or opiate withdrawal in opiate dependency. It is approved in the United Kingdom, but is still undergoing clinical trials in the United States.

Structure
Thumb
Synonyms
2-(alpha-(2,6-Dichlorophenoxy)ethyl)2-imidazoline
Lofexidina
Lofexidinum
External Identifiers Not Available
Approved Prescription ProductsNot Available
Approved Generic Prescription ProductsNot Available
Approved Over the Counter ProductsNot Available
Unapproved/Other Products Not Available
International Brands
NameCompany
BritlofexBritannia
Brand mixturesNot Available
Salts
Name/CASStructureProperties
Lofexidine hydrochloride
Thumb
  • InChI Key: DWWHMKBNNNZGHF-UHFFFAOYNA-N
  • Monoisotopic Mass: 294.009346169
  • Average Mass: 295.593
DBSALT000829
Categories
UNIIUI82K0T627
CAS number31036-80-3
WeightAverage: 259.132
Monoisotopic: 258.03266843
Chemical FormulaC11H12Cl2N2O
InChI KeyInChIKey=KSMAGQUYOIHWFS-UHFFFAOYSA-N
InChI
InChI=1S/C11H12Cl2N2O/c1-7(11-14-5-6-15-11)16-10-8(12)3-2-4-9(10)13/h2-4,7H,5-6H2,1H3,(H,14,15)
IUPAC Name
2-[1-(2,6-dichlorophenoxy)ethyl]-4,5-dihydro-1H-imidazole
SMILES
CC(OC1=C(Cl)C=CC=C1Cl)C1=NCCN1
Taxonomy
DescriptionThis compound belongs to the class of organic compounds known as phenol ethers. These are aromatic compounds containing an ether group substituted with a benzene ring.
KingdomOrganic compounds
Super ClassBenzenoids
ClassBenzene and substituted derivatives
Sub ClassPhenol ethers
Direct ParentPhenol ethers
Alternative Parents
Substituents
  • Phenol ether
  • 1,3-dichlorobenzene
  • Halobenzene
  • Chlorobenzene
  • Alkyl aryl ether
  • Imidolactam
  • Aryl halide
  • Aryl chloride
  • 2-imidazoline
  • Azacycle
  • Organoheterocyclic compound
  • Organic 1,3-dipolar compound
  • Propargyl-type 1,3-dipolar organic compound
  • Carboximidamide
  • Ether
  • Carboxylic acid amidine
  • Amidine
  • Hydrocarbon derivative
  • Organooxygen compound
  • Organonitrogen compound
  • Organochloride
  • Organohalogen compound
  • Aromatic heteromonocyclic compound
Molecular FrameworkAromatic heteromonocyclic compounds
External DescriptorsNot Available
Pharmacology
IndicationInvestigated for use/treatment in addictions and substance abuse.
PharmacodynamicsLofexidine is an orally active imidazoline adrenergic alpha-2-receptor agonist; and is believed to have a high affinity for 2A receptor subtypes resulting in less anti-hypertensive activity than clonidine, a non-selective alpha-2-receptor agonist. Hypotension may occur in susceptible subjects, accompanied by a decrease in heart rate. Abrupt discontinuation of lofexidine has been, in some cases, associated with a transient increase in blood pressure to higher than pre-treatment levels. 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, also known as adrenaline, and norepinephrine) in the adrenal medulla. By fooling the brain into believing that catecholamine levels are higher than they really are, lofexidine 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. This central action is responsible for the suppression of opiate withdrawal symptoms.
Mechanism of actionLofexidine is an alpha2-adrenergic receptor agonist.
Related Articles
AbsorptionLofexidine is extensively absorbed and achieves peak plasma concentration at 3 hours after administration of a single dose. Bioavailability is over 90% following oral administration.
Volume of distributionNot Available
Protein binding80 to 90%
Metabolism

Lofexidine undergoes extensive metabolism in the liver and excretion is mainly by the kidney.

Route of eliminationNot Available
Half life11 hours
ClearanceNot Available
ToxicityLofexidine was tolerated at high dosage in singe dose toxicity studies in animals, the LD50 being >77 mg/kg. With repeat dosing in mice, rats and dogs symptoms related to the pharmacology of the drug (ataxia, sedation, tremor, unkempt appearance and exhaustion) appeared. Overdosage may cause hypotension, bradycardia and sedation.
Affected organisms
  • Humans and other mammals
PathwaysNot Available
SNP Mediated EffectsNot Available
SNP Mediated Adverse Drug ReactionsNot Available
ADMET
Predicted ADMET features
PropertyValueProbability
Human Intestinal Absorption+0.9969
Blood Brain Barrier+0.9582
Caco-2 permeable+0.539
P-glycoprotein substrateSubstrate0.7119
P-glycoprotein inhibitor INon-inhibitor0.9326
P-glycoprotein inhibitor IINon-inhibitor0.8089
Renal organic cation transporterInhibitor0.6897
CYP450 2C9 substrateNon-substrate0.744
CYP450 2D6 substrateNon-substrate0.6421
CYP450 3A4 substrateNon-substrate0.5055
CYP450 1A2 substrateInhibitor0.8023
CYP450 2C9 inhibitorNon-inhibitor0.739
CYP450 2D6 inhibitorInhibitor0.6616
CYP450 2C19 inhibitorNon-inhibitor0.6593
CYP450 3A4 inhibitorNon-inhibitor0.9304
CYP450 inhibitory promiscuityHigh CYP Inhibitory Promiscuity0.5075
Ames testNon AMES toxic0.7322
CarcinogenicityNon-carcinogens0.913
BiodegradationNot ready biodegradable0.996
Rat acute toxicity2.9567 LD50, mol/kg Not applicable
hERG inhibition (predictor I)Weak inhibitor0.6244
hERG inhibition (predictor II)Non-inhibitor0.7293
ADMET data is predicted using admetSAR, a free tool for evaluating chemical ADMET properties. (23092397 )
Pharmacoeconomics
ManufacturersNot Available
PackagersNot Available
Dosage formsNot Available
PricesNot Available
PatentsNot Available
Properties
StateSolid
Experimental Properties
PropertyValueSource
melting point221-223U.S. Patent 3,966,757.
Predicted Properties
PropertyValueSource
Water Solubility0.147 mg/mLALOGPS
logP3.31ALOGPS
logP2.66ChemAxon
logS-3.2ALOGPS
pKa (Strongest Basic)7.67ChemAxon
Physiological Charge1ChemAxon
Hydrogen Acceptor Count3ChemAxon
Hydrogen Donor Count1ChemAxon
Polar Surface Area33.62 Å2ChemAxon
Rotatable Bond Count3ChemAxon
Refractivity64.41 m3·mol-1ChemAxon
Polarizability25.11 Å3ChemAxon
Number of Rings2ChemAxon
Bioavailability1ChemAxon
Rule of FiveYesChemAxon
Ghose FilterYesChemAxon
Veber's RuleYesChemAxon
MDDR-like RuleYesChemAxon
Spectra
Mass Spec (NIST)Not Available
SpectraNot Available
References
Synthesis Reference

U.S. Patent 3,966,757.

General References
  1. Walsh SL, Strain EC, Bigelow GE: Evaluation of the effects of lofexidine and clonidine on naloxone-precipitated withdrawal in opioid-dependent humans. Addiction. 2003 Apr;98(4):427-39. [PubMed:12653813 ]
External Links
ATC CodesN07BC04
AHFS CodesNot Available
PDB EntriesNot Available
FDA labelNot Available
MSDSNot Available
Interactions
Drug InteractionsNot Available
Food InteractionsNot Available

Targets

Kind
Protein
Organism
Human
Pharmacological action
yes
Actions
agonist
General Function:
Thioesterase binding
Specific Function:
Alpha-2 adrenergic receptors mediate the catecholamine-induced inhibition of adenylate cyclase through the action of G proteins. The rank order of potency for agonists of this receptor is oxymetazoline > clonidine > epinephrine > norepinephrine > phenylephrine > dopamine > p-synephrine > p-tyramine > serotonin = p-octopamine. For antagonists, the rank order is yohimbine > phentolamine = mianser...
Gene Name:
ADRA2A
Uniprot ID:
P08913
Molecular Weight:
48956.275 Da
References
  1. Jin Y, Verstappen A, Elko E, Cammarata P, Yorio T: Effects of lofexidine, an alpha 2-adrenoreceptor agonist, on ocular blood flow and ion transport of rabbit iris-ciliary body. J Ocul Pharmacol. 1992 Spring;8(1):23-33. [PubMed:1357064 ]
  2. Strang J, Bearn J, Gossop M: Lofexidine for opiate detoxification: review of recent randomised and open controlled trials. Am J Addict. 1999 Fall;8(4):337-48. [PubMed:10598217 ]
  3. Erb S, Hitchcott PK, Rajabi H, Mueller D, Shaham Y, Stewart J: Alpha-2 adrenergic receptor agonists block stress-induced reinstatement of cocaine seeking. Neuropsychopharmacology. 2000 Aug;23(2):138-50. [PubMed:10882840 ]
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Drug created on October 21, 2007 16:23 / Updated on May 20, 2014 12:14