- Phentolamine
-
Phentolamine 
Systematic (IUPAC) name 3-[(4,5-dihydro-1H-imidazol-2-ylmethyl)(4-methylphenyl)amino]phenol Clinical data Trade names Regitine AHFS/Drugs.com Micromedex Detailed Consumer Information Pregnancy cat. C (U.S.) Legal status ? Routes Usually IV or IM Pharmacokinetic data Metabolism Hepatic Half-life 19 minutes Identifiers CAS number 50-60-2 ATC code C04AB01 V03AB36 PubChem CID 5775 IUPHAR ligand 502 DrugBank APRD00615 ChemSpider 5571 
UNII Z468598HBV KEGG D08362 ChEMBL CHEMBL597 Chemical data Formula C17H19N3O Mol. mass 281.352 g/mol SMILES eMolecules & PubChem - InChI=1S/C17H19N3O/c1-13-5-7-14(8-6-13)20(12-17-18-9-10-19-17)15-3-2-4-16(21)11-15/h2-8,11,21H,9-10,12H2,1H3,(H,18,19)
Key:MRBDMNSDAVCSSF-UHFFFAOYSA-N
(what is this?) (verify)Phentolamine (Regitine) is a reversible[1] nonselective alpha-adrenergic antagonist. [2]
Contents
Mechanism
Its primary action is vasodilation due to α1 blockade.[3]
It also can lead to reflex tachycardia because of hypotension and α2 inhibition, which increases sympathetic tone.[4]
Uses
The primary application for phentolamine is for the control of hypertensive emergencies, most notably due to pheochromocytoma.[5]
It also has usefulness in the treatment of cocaine induced hypertension, where one would generally avoid beta blockers and where calcium channel blockers are not effective. Beta-blockers (i.e. metoprolol) or combined alpha and beta adrenergic blocking agents (i.e. labetalol) should be avoided in patients with a history of cocaine abuse. They can cause an unopposed alpha-adrenergic mediated coronary vasoconstriction, causing the worsening of myocardial ischemia and hypertension.
[6][7] In this context it is probably most safely given by infusion since bolus doses have a propensity towards causing precipitous falls in blood pressure.
When given by injection it causes blood vessels to expand, thereby increasing blood flow. When injected into the penis (intracavernosal), it increases blood flow to the penis, which results in an erection.[8]
It may be stored in crash carts to counteract severe peripheral vasoconstriction secondary to extravasation of peripherally placed vasopressor infusions, typically of norepinephrine. Epinephrine infusions are less vasoconstrictive than norepinephrine as they primarily stimulate beta receptor more than alpha receptors, but the effect remains dose dependent.
Phentolamine also has diagnostic and therapeutic roles in complex regional pain syndrome (reflex sympathetic dystrophy).[9]
Phentolamine has recently been introduced in the dental field as a local anesthetic reversal agent. Distributed by Septodont, OraVerse is a Phentolamine Mesylate injection designed to reverse the local vasoconstrictor properties used in many local anesthetics to prolong anesthesia.[10] OraVerse has been shown to accelerate the reversal of the lingering soft-tissue numbness associated with the widely used anesthetic-vasoconstrictor combinations.[11]
Chemistry
Phentolamine, 2-[[N-(3′-hydroxyphenyl)-para-toluidion]methyl]-2-imidazoline, is synthesized by alkylation of 3-(4-methylanilino)phenol using 2-chloromethylimidazoline.
- K. Miescher, A. Marxer, E. Urech, U.S. Patent 2,503,059 (1950).
- E. Urech, A. Marxer, K. Miescher, Helv. Chim. Acta, 33, 1386 (1950).
References
- ^ Jewell, John R.; Longworth, David L.; Stoller, James K.; Casey, David (2003). The Cleveland Clinic internal medicine case reviews. Hagerstown, MD: Lippincott Williams & Wilkins. p. 32. ISBN 0-7817-4266-8.
- ^ MeSH Phentolamine
- ^ Brock G. Oral phentolamine (Vasomax). Drugs Today (Barcelona). 2000 Feb-Mar;36(2-3):121-4.
- ^ Shen, Howard (2008). Illustrated Pharmacology Memory Cards: PharMnemonics. Minireview. p. 14. ISBN 1-59541-101-1.
- ^ Tuncel M, Ram VC. Hypertensive emergencies. Etiology and management. American Journal of Cardiovascular Drugs. 2003;3(1):21-31.
- ^ Hollander JE, Henry TD. Evaluation and management of the patient who has cocaine-associated chest pain. Cardiology Clinics. 2006 Feb;24(1):103-14.
- ^ Chan GM, Sharma R, Price D, Hoffman RS, Nelson LS. Phentolamine Therapy for Cocaine-Association Acute Coronary Syndrome (CAACS). Journal of Medical Toxicology. 2006 Sep;2(3):108-11.
- ^ Bella AJ, Brock GB. Intracavernous pharmacotherapy for erectile dysfunction. Endocrine. 2004 Mar-Apr;23(2-3):149-55.
- ^ Rowbotham MC. Pharmacologic management of complex regional pain syndrome. Clinical Journal of Pain. 2006 Jun;22(5):425-9.
- ^ http://www.novalar.com/oraverse-dental-specialty-pharmaceutical
- ^ Malamed S. What's new in local anaesthesia? Society For The Advancement Of Anaesthesia In Dentistry Digest. 2009 Jan;25:4-14.
Sympatholytic (and closely related) antihypertensives (C02) Sympatholytics
(antagonize α-adrenergic
vasoconstriction)CentralAdrenergic release inhibitorsBethanidine • Bretylium • Debrisoquine • Guanadrel • Guanazodine • Guanethidine • Guanoclor • Guanoxan • Guanazodine • Guanoxabenz • GuanoxanImidazoline receptor agonistMecamylamine • Pentolinium • TrimethaphanPeripheralIndirectTyrosine hydroxylase inhibitorDirectNon-selective α blockerPhentolamineOther antagonists Endothelin antagonist (for PH)Peripheral vasodilators (C04) 2-amino-1-phenylethanol derivatives Isoxsuprine • Buphenine • BamethanImidazoline derivatives/
Alpha blockersPhentolamine • Tolazoline • PhenoxybenzamineNiacin and derivatives Purine derivatives Pentifylline • Xantinol nicotinate • Pentoxifylline • Etofylline nicotinateErgot alkaloids Other peripheral vasodilators Cyclandelate • Phenoxybenzamine • Vincamine • Moxisylyte • Bencyclane • Vinburnine • Sulcotidil • Buflomedil • Naftidrofuryl • Butalamine • Visnadine • Cetiedil • Cinepazide • Ifenprodil • Azapetine • FasudilFor erectile dysfunction Prostaglandins (E)Moxisylyte • Phentolamine • YohimbineDopamine D4 receptor agonistsABT-670 • ABT-724OthersFor premature ejaculation Oxytocin receptor antagonistsEpelsibanAdrenergics Receptor ligands Agonists: 5-FNE • 6-FNE • Amidephrine • Anisodamine • Anisodine • Cirazoline • Dipivefrine • Dopamine • Ephedrine • Epinephrine (Adrenaline) • Etilefrine • Ethylnorepinephrine • Indanidine • Levonordefrin • Metaraminol • Methoxamine • Methyldopa • Midodrine • Naphazoline • Norepinephrine (Noradrenaline) • Octopamine • Oxymetazoline • Phenylephrine • Phenylpropanolamine • Pseudoephedrine • Synephrine • Tetrahydrozoline
Antagonists: Abanoquil • Adimolol • Ajmalicine • Alfuzosin • Amosulalol • Arotinolol • Atiprosin • Benoxathian • Buflomedil • Bunazosin • Carvedilol • CI-926 • Corynanthine • Dapiprazole • DL-017 • Domesticine • Doxazosin • Eugenodilol • Fenspiride • GYKI-12,743 • GYKI-16,084 • Indoramin • Ketanserin • L-765,314 • Labetalol • Mephendioxan • Metazosin • Monatepil • Moxisylyte (Thymoxamine) • Naftopidil • Nantenine • Neldazosin • Nicergoline • Niguldipine • Pelanserin • Phendioxan • Phenoxybenzamine • Phentolamine • Piperoxan • Prazosin • Quinazosin • Ritanserin • RS-97,078 • SGB-1,534 • Silodosin • SL-89.0591 • Spiperone • Talipexole • Tamsulosin • Terazosin • Tibalosin • Tiodazosin • Tipentosin • Tolazoline • Trimazosin • Upidosin • Urapidil • Zolertine
* Note that many TCAs, TeCAs, antipsychotics, ergolines, and some piperazines like buspirone, trazodone, nefazodone, etoperidone, and mepiprazole all antagonize α1-adrenergic receptors as well, which contributes to their side effects such as orthostatic hypotension.Agonists: (R)-3-Nitrobiphenyline • 4-NEMD • 6-FNE • Amitraz • Apraclonidine • Brimonidine • Cannabivarin • Clonidine • Detomidine • Dexmedetomidine • Dihydroergotamine • Dipivefrine • Dopamine • Ephedrine • Ergotamine • Epinephrine (Adrenaline) • Esproquin • Etilefrine • Ethylnorepinephrine • Guanabenz • Guanfacine • Guanoxabenz • Levonordefrin • Lofexidine • Medetomidine • Methyldopa • Mivazerol • Naphazoline • Norepinephrine (Noradrenaline) • Phenylpropanolamine • Piperoxan • Pseudoephedrine • Rilmenidine • Romifidine • Talipexole • Tetrahydrozoline • Tizanidine • Tolonidine • Urapidil • Xylazine • Xylometazoline
Antagonists: 1-PP • Adimolol • Aptazapine • Atipamezole • BRL-44408 • Buflomedil • Cirazoline • Efaroxan • Esmirtazapine • Fenmetozole • Fluparoxan • GYKI-12,743 • GYKI-16,084 • Idazoxan • Mianserin • Mirtazapine • MK-912 • NAN-190 • Olanzapine • Phentolamine • Phenoxybenzamine • Piperoxan • Piribedil • Rauwolscine • Rotigotine • SB-269,970 • Setiptiline • Spiroxatrine • Sunepitron • Tolazoline • Yohimbine
* Note that many atypical antipsychotics and azapirones like buspirone and gepirone (via metabolite 1-PP) antagonize α2-adrenergic receptors as well.βAgonists: 2-FNE • 5-FNE • Amibegron • Arbutamine • Arformoterol • Arotinolol • BAAM • Bambuterol • Befunolol • Bitolterol • Broxaterol • Buphenine • Carbuterol • Cimaterol • Clenbuterol • Denopamine • Deterenol • Dipivefrine • Dobutamine • Dopamine • Dopexamine • Ephedrine • Epinephrine (Adrenaline) • Etafedrine • Etilefrine • Ethylnorepinephrine • Fenoterol • Formoterol • Hexoprenaline • Higenamine • Indacaterol • Isoetarine • Isoprenaline (Isoproterenol) • Isoxsuprine • Labetalol • Levonordefrin • Levosalbutamol • Mabuterol • Methoxyphenamine • Methyldopa • Norepinephrine (Noradrenaline) • Orciprenaline • Oxyfedrine • Phenylpropanolamine • Pirbuterol • Prenalterol • Ractopamine • Procaterol • Pseudoephedrine • Reproterol • Rimiterol • Ritodrine • Salbutamol (Albuterol) • Salmeterol • Solabegron • Terbutaline • Tretoquinol • Tulobuterol • Xamoterol • Zilpaterol • Zinterol
Antagonists: Acebutolol • Adaprolol • Adimolol • Afurolol • Alprenolol • Alprenoxime • Amosulalol • Ancarolol • Arnolol • Arotinolol • Atenolol • Befunolol • Betaxolol • Bevantolol • Bisoprolol • Bopindolol • Bormetolol • Bornaprolol • Brefonalol • Bucindolol • Bucumolol • Bufetolol • Buftiralol • Bufuralol • Bunitrolol • Bunolol • Bupranolol • Burocrolol • Butaxamine • Butidrine • Butofilolol • Capsinolol • Carazolol • Carpindolol • Carteolol • Carvedilol • Celiprolol • Cetamolol • Cicloprolol • Cinamolol • Cloranolol • Cyanopindolol • Dalbraminol • Dexpropranolol • Diacetolol • Dichloroisoprenaline • Dihydroalprenolol • Dilevalol • Diprafenone • Draquinolol • Dropranolol • Ecastolol • Epanolol • Ericolol • Ersentilide • Esatenolol • Esmolol • Esprolol • Eugenodilol • Exaprolol • Falintolol • Flestolol • Flusoxolol • Hydroxycarteolol • Hydroxytertatolol • ICI-118,551 • Idropranolol • Indenolol • Indopanolol • Iodocyanopindolol • Iprocrolol • Isoxaprolol • Isamoltane • Labetalol • Landiolol • Levobetaxolol • Levobunolol • Levocicloprolol • Levomoprolol • Medroxalol • Mepindolol • Metalol • Metipranolol • Metoprolol • Moprolol • Nadolol • Nadoxolol • Nafetolol • Nebivolol • Neraminol • Nifenalol • Nipradilol • Oberadilol • Oxprenolol • Pacrinolol • Pafenolol • Pamatolol • Pargolol • Parodilol • Penbutolol • Penirolol • PhQA-33 • Pindolol • Pirepolol • Practolol • Primidolol • Procinolol • Pronethalol • Propafenone • Propranolol • Ridazolol • Ronactolol • Soquinolol • Sotalol • Spirendolol • SR 59230A • Sulfinalol • TA-2005 • Talinolol • Tazolol • Teoprolol • Tertatolol • Terthianolol • Tienoxolol • Tilisolol • Timolol • Tiprenolol • Tolamolol • Toliprolol • Tribendilol • Trigevolol • Xibenolol • XipranololReuptake inhibitors Selective norepinephrine reuptake inhibitors: Amedalin • Atomoxetine (Tomoxetine) • Ciclazindol • Daledalin • Esreboxetine • Lortalamine • Mazindol • Nisoxetine • Reboxetine • Talopram • Talsupram • Tandamine • Viloxazine; Norepinephrine-dopamine reuptake inhibitors: Amineptine • Bupropion (Amfebutamone) • Fencamine • Fencamfamine • Lefetamine • Levophacetoperane • LR-5182 • Manifaxine • Methylphenidate • Nomifensine • O-2172 • Radafaxine; Serotonin-norepinephrine reuptake inhibitors: Bicifadine • Desvenlafaxine • Duloxetine • Eclanamine • Levomilnacipran • Milnacipran • Sibutramine • Venlafaxine; Serotonin-norepinephrine-dopamine reuptake inhibitors: Brasofensine • Diclofensine • DOV-102,677 • DOV-21,947 • DOV-216,303 • JNJ-7925476 • JZ-IV-10 • Methylnaphthidate • Naphyrone • NS-2359 • PRC200-SS • SEP-225,289 • SEP-227,162 • Tesofensine; Tricyclic antidepressants: Amitriptyline • Butriptyline • Cianopramine • Clomipramine • Desipramine • Dosulepin • Doxepin • Imipramine • Lofepramine • melitracen • Nortriptyline • Protriptyline • Trimipramine; Tetracyclic antidepressants: Amoxapine • Maprotiline • Mianserin • Oxaprotiline • Setiptiline; Others: Cocaine • CP-39,332 • EXP-561 • Fezolamine • Ginkgo biloba • Indeloxazine • Nefazodone • Nefopam • Pridefrine • Tapentadol • Tedatioxetine • Teniloxazine • Tramadol • ZiprasidoneEnzyme inhibitors 3,4-DihydroxystyreneDBHCGS-19281A • SKF-64139 • SKF-7698Nonselective: Benmoxin • Caroxazone • Echinopsidine • Furazolidone • Hydralazine • Indantadol • Iproclozide • Iproniazid • Isocarboxazid • Isoniazid • Linezolid • Mebanazine • Metfendrazine • Nialamide • Octamoxin • Paraxazone • Phenelzine • Pheniprazine • Phenoxypropazine • Pivalylbenzhydrazine • Procarbazine • Safrazine • Tranylcypromine; MAO-A selective: Amiflamine • Bazinaprine • Befloxatone • Befol • Brofaromine • Cimoxatone • Clorgiline • Esuprone • Harmala alkaloids (Harmine, Harmaline, Tetrahydroharmine, Harman, Norharman, etc) • Methylene Blue • Metralindole • Minaprine • Moclobemide • Pirlindole • Sercloremine • Tetrindole • Toloxatone • Tyrima; MAO-B selective: D-Deprenyl • Selegiline (L-Deprenyl) • Ladostigil • Lazabemide • Milacemide • Mofegiline • Pargyline • Rasagiline • Safinamide
* Note that MAO-B inhibitors also influence norepinephrine/epinephrine levels since they inhibit the breakdown of their precursor dopamine.COMTOthers Ferrous Iron (Fe2+) • S-Adenosyl-L-Methionine • Vitamin B3 (Niacin, Nicotinamide → NADPH) • Vitamin B6 (Pyridoxine, Pyridoxamine, Pyridoxal → Pyridoxal Phosphate) • Vitamin B9 (Folic acid → Tetrahydrofolic acid) • Vitamin C (Ascorbic acid) • Zinc (Zn2+)OthersActivity enhancers: BPAP • PPAP; Release blockers: Bethanidine • Bretylium • Guanadrel • Guanazodine • Guanclofine • Guanethidine • Guanoxan; Toxins: Oxidopamine (6-Hydroxydopamine)List of adrenergic drugsCategories:- Antihypertensive agents
- Vasodilators
- Imidazolines
- Alpha blockers
- Phenols
- Anilines
- InChI=1S/C17H19N3O/c1-13-5-7-14(8-6-13)20(12-17-18-9-10-19-17)15-3-2-4-16(21)11-15/h2-8,11,21H,9-10,12H2,1H3,(H,18,19)
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