Methyldopa

Methyldopa
Clinical data

Trade names	Aldomet, Aldoril, Dopamet, others
AHFS/Drugs.com	Monograph
MedlinePlus	a682242
Pregnancy category	AU: A US: B (No risk in non-human studies)
Routes of administration	Oral, IV
ATC code	C02AB01 (WHO) C02AB02 (WHO) (racemic)
Legal status
Legal status	AU: S4 (Prescription only) CA: ℞-only UK: POM (Prescription only) US: ℞-only
Pharmacokinetic data
Bioavailability	approximately 50%
Metabolism	Hepatic
Biological half-life	105 minutes
Excretion	Renal for metabolites
Identifiers
IUPAC name (S)-2-amino-3-(3,4-dihydroxyphenyl)-2-methyl-propanoic acid
Synonyms	L-α-Methyl-3,4-dihydroxyphenylalanine
CAS Number	555-30-6^Y
PubChem (CID)	38853 CID 40175
IUPHAR/BPS	5217
DrugBank	DB00968^Y
ChemSpider	35562^N
UNII	56LH93261Y^Y
ChEMBL	CHEMBL459^N
ECHA InfoCard	100.008.264
Chemical and physical data
Formula	C₁₀H₁₃NO₄
Molar mass	211.215 g/mol
3D model (Jmol)	Interactive image
SMILES C[C@](CC1=CC(=C(C=C1)O)O)(C(=O)O)N
InChI InChI=1S/C10H13NO4/c1-10(11,9(14)15)5-6-2-3-7(12)8(13)4-6/h2-4,12-13H,5,11H2,1H3,(H,14,15)/t10-/m0/s1^N Key:CJCSPKMFHVPWAR-JTQLQIEISA-N^N
^NY (what is this?) (verify)

Wikimedia Commons has media related to Methyldopa.

Methyldopa, sold under the brand name Aldomet among others, is a centrally acting antihypertensive agent. Its is no longer frequently used following the introduction of alternative safer classes of agents. However, it continues to have a role in otherwise difficult to treat hypertension and gestational hypertension.

It is metabolized to alpha-methylnorepinephrine in the brain, and this compound is thought to activate central alpha-2 adrenergic receptors (Gerber, 1990). Being a selective agonist for α₂ adrenergic receptors, psychoactive drug is used as a sympatholytic or antihypertensive.

Methydopa was discovered in 1960.^[1] It is on the World Health Organization's List of Essential Medicines, the most important medication needed in a basic health system.^[2]

Medical uses

Methyldopa is used in the clinical treatment of the following disorders:

Hypertension (or high blood pressure)
Gestational hypertension (or pregnancy-induced hypertension) and pre-eclampsia

Side effects

Methyldopa is capable of inducing a number of adverse side effects, which range from mild to severe. Nevertheless, they are generally mild when the dose is less than 1 gram per day.^[3] Side effects may include:

Psychological
- Depression and/or even suicidal ideation, as well as nightmares
- Apathy and/or anhedonia, as well as dysphoria
- Anxiety, especially of the social anxiety variant
- Decreased alertness, awareness, and wakefulness
- Impaired attention, focus, and concentration
- Decreased desire, drive, and motivation
- Fatigue or lethargy and/or malaise or lassitude
- Sedation or drowsiness and/or somnolence or sleepiness
- Agitation or restlessness
- Cognitive and memory impairment
- Derealization and/or depersonalization, as well as mild psychosis
- Sexual dysfunction including impaired libido, desire, and drive
Physiological
- Dizziness, lightheadedness, or vertigo
- Miosis or pupil constriction
- Xerostomia or dry mouth
- Gastrointestinal disturbances such as diarrhea and/or constipation
- Headache or migraine
- Myalgia or muscle aches, arthralgia or joint pain, and/or paresthesia ("pins and needles")
- Restless legs syndrome (RLS)
- Parkinsonian symptoms such as muscle tremors, rigidity, hypokinesia, and/or balance or postural instability
- Akathisia, ataxia, dyskinesia as well as even tardive dyskinesia, and/or dystonia
- Bell's palsy or facial paralysis
- Sexual dysfunction consisting of impaired erectile dysfunction and/or anorgasmia
- Hyperprolactinemia or excess prolactin, gynecomastia/breast enlargement in males, and/or amenorrhoea or absence of menstrual cycles in females
- Bradycardia or decreased heart rate
- Hypotension or decreased blood pressure (though this may also be considered a therapeutic benefit)
- Orthostatic hypotension (also known as postural hypotension)
- Hepatitis, hepatotoxicity, or liver dysfunction or damage
- Pancreatitis or inflammation of the pancreas
- Haemolytic anaemia or deficiency in red blood cells (RBCs)
- Myelotoxicity or bone marrow suppression, potentially leading to thrombocytopenia or blood platelet deficiency and/or leukopenia or white blood cell (WBC) deficiency
- Hypersensitivity such as lupus erythematosus, myocarditis, and/or pericarditis
- Lichenoid reactions such as skin lesions and/or rashes
- Pallor

Rebound/withdrawal

Rebound hypertension via withdrawal on account of tolerance upon the abrupt discontinuation of methyldopa has been reported.^[4]

Mechanism of Action

Methyldopa has a dual mechanism of action:

It is a competitive inhibitor of the enzyme DOPA decarboxylase, also known as aromatic L-amino acid decarboxylase, which converts L-DOPA into dopamine. Dopamine is a precursor for norepinephrine (noradrenaline) and subsequently epinephrine (adrenaline). This inhibition results in reduced dopaminergic and adrenergic neurotransmission in the peripheral nervous system. This effect may lower blood pressure and cause central nervous system effects such as depression, anxiety, apathy, anhedonia, and parkinsonism. In addition, decreased dopamine may reduce its inhibitory effect on prolactin leading to signs and symptoms of hyperprolactinemia.
It is converted to α-methylnorepinephrine by dopamine beta-hydroxylase (DBH). α-methylnorepinephrine is an agonist of presynaptic central nervous system α₂ adrenergic receptors. Activation of these receptors in the brainstem appears to inhibit sympathetic nervous system output and lower blood pressure. This is also the mechanism of action of clonidine.

Pharmacokinetics

Methyldopa exhibits variable absorption from the gastrointestinal tract. It is metabolized in the liver and intestines and is excreted in urine.

History

When methyldopa was first introduced, it was the mainstay of antihypertensive treatment, but its use has declined on account of relatively severe adverse side effects, with increased use of other safer and more tolerable agents such as alpha blockers, beta blockers, and calcium channel blockers. Additionally, it has yet to be associated with reducing adverse cardiovascular events including myocardial infarction and stroke, or overall all-cause mortality reduction in clinical trials.^[5] Nonetheless, one of methyldopa's still current indications is in the management of pregnancy-induced hypertension (PIH), as it is relatively safe in pregnancy compared to many other antihypertensives which may affect the fetus.

References

↑ Walker, S. R. (2012). Trends and Changes in Drug Research and Development. Springer Science & Business Media. p. 109. ISBN 9789400926592.
↑ "WHO Model List of EssentialMedicines" (PDF). World Health Organization. October 2013. Retrieved 22 April 2014.
↑ British National Formulary 56. September 2008. pp. 95–96. ISBN 978-0-85369-778-7.
↑ Methyldopa (PIM 342)
↑ Mah GT, Tejani AM, Musini VM. Methyldopa for primary hypertension. Cochrane Database of Systematic Reviews 2009, Issue 4. Art. No.: CD003893. DOI: 10.1002/14651858.CD003893.pub3.

Sympatholytic (and closely related) antihypertensives (C02)

Sympatholytics
(antagonize α-adrenergic
vasoconstriction)

Central

α₂ agonist	Clonidine Guanabenz Guanfacine Methyldopa^# Tiamenidine^‡

Adrenergic release inhibitors	Bethanidine Bretylium Debrisoquine Guanadrel Guanazodine Guanethidine Guanoclor Guanazodine Guanoxabenz Guanoxan

Imidazoline receptor agonist	Moxonidine Rilmenidine Tolonidine

Ganglion-blocking/nicotinic antagonist	Hexamethonium^‡ Mecamylamine Pentolinium Trimethaphan

Peripheral

Indirect

MAOI	Pargyline^‡

Adrenergic uptake inhibitor	Bietaserpine Deserpidine Methoserpidine Rescinnamine Reserpine

Tyrosine hydroxylase inhibitor	Metirosine

Direct

α₁ blockers	Prazosin Indoramin Trimazosin Doxazosin Urapidil

Non-selective α blocker	Phentolamine

Other antagonists

Serotonin antagonist	Ketanserin Lidanserin

Endothelin antagonist (for PH)	dual (Bosentan, Macitentan) selective (Ambrisentan, Sitaxentan)

^#WHO-EM
^‡Withdrawn from market
Clinical trials:
- ^†Phase III
- ^§Never to phase III

Antiparkinson agents (N04)

Dopaminergics

DA precursors/prodrugs	Levodopa^# Melevodopa

DA receptor agonists	Apomorphine Bromocriptine Cabergoline Dihydroergocryptine Lisuride Pergolide Piribedil Pramipexole Ropinirole Rotigotine

MAO-B inhibitors	Rasagiline Selegiline

COMT inhibitors	Entacapone Tolcapone

AAAD inhibitors	Benserazide Carbidopa^#

Anticholinergics

Others

^#WHO-EM
^‡Withdrawn from market
Clinical trials:
- ^†Phase III
- ^§Never to phase III

Adrenergic receptor modulators

α₁

Agonists 6-FNE Amidephrine Anisodine Buspirone Cirazoline Corbadrine Dexisometheptene Dipivefrine Dopamine Droxidopa (L-DOPS) Ephedrine Epinephrine Etilefrine Etilevodopa Ethylnorepinephrine Indanidine Isometheptene L-DOPA (levodopa) L-Phenylalanine L-Tyrosine Melevodopa Metaraminol Methoxamine Methyldopa Midodrine Naphazoline Norepinephrine Octopamine (drug) Oxymetazoline Phenylephrine Phenylpropanolamine Pseudoephedrine Synephrine Tetryzoline Tiamenidine XP21279 Xylometazoline

Antagonists Abanoquil Adimolol Ajmalicine Alfuzosin Amosulalol Anisodamine Arotinolol Atiprosin Atypical antipsychotics (e.g., clozapine, olanzapine, quetiapine, risperidone) Benoxathian Buflomedil Bunazosin Carvedilol Corynanthine Dapiprazole Domesticine Doxazosin Ergolines (e.g., ergotamine, dihydroergotamine, lisuride, terguride) Etoperidone Eugenodilol Fenspiride Hydroxyzine Indoramin Ketanserin L-765,314 Labetalol mCPP Mepiprazole Metazosin Monatepil Moxisylyte Naftopidil Nantenine Nefazodone Neldazosin Niaprazine Nicergoline Niguldipine Pardoprunox Pelanserin Phendioxan Phenoxybenzamine Phentolamine Piperoxan Prazosin Quinazosin Ritanserin Silodosin Spiperone Talipexole Tamsulosin Terazosin Tiodazosin Tolazoline Trazodone Tetracyclic antidepressants (e.g., amoxapine, maprotiline, mianserin) Tricyclic antidepressants (e.g., amitriptyline, clomipramine, doxepin, imipramine, trimipramine) Trimazosin Typical antipsychotics (e.g., chlorpromazine, fluphenazine, loxapine, thioridazine) Urapidil WB-4101 Zolertine

α₂

Agonists (R)-3-Nitrobiphenyline 4-NEMD 6-FNE Amitraz Apraclonidine Brimonidine Cannabivarin Clonidine Corbadrine Detomidine Dexmedetomidine Dihydroergotamine Dipivefrine Dopamine Droxidopa (L-DOPS) Etilevodopa Ephedrine Ergotamine Epinephrine Etilefrine Ethylnorepinephrine Guanabenz Guanfacine Guanoxabenz L-DOPA (levodopa) L-Phenylalanine L-Tyrosine Lofexidine Medetomidine Melevodopa Methyldopa Mivazerol Naphazoline Norepinephrine Oxymetazoline Phenylpropanolamine Piperoxan Pseudoephedrine Rilmenidine Romifidine Talipexole Tetrahydrozoline Tiamenidine Tizanidine Tolonidine Urapidil XP21279 Xylazine Xylometazoline

Antagonists 1-PP Adimolol Aptazapine Atipamezole Atypical antipsychotics (e.g., asenapine, clozapine, lurasidone, paliperidone, quetiapine, risperidone, zotepine) Azapirones (e.g., buspirone, tandospirone) BRL-44408 Buflomedil Cirazoline Efaroxan Esmirtazapine Fenmetozole Fluparoxan Idazoxan mCPP Mianserin Mirtazapine NAN-190 Olanzapine Pardoprunox Phentolamine Phenoxybenzamine Piperoxan Piribedil Rauwolscine Rotigotine SB-269970 Setiptiline Spiroxatrine Sunepitron Tolazoline Typical antipsychotics (e.g., chlorpromazine, fluphenazine, loxapine, thioridazine) Yohimbine

Agonists Abediterol Alifedrine Amibegron Arbutamine Arformoterol Arotinolol BAAM Bambuterol Befunolol Bitolterol Broxaterol Buphenine Carbuterol Carmoterol Cimaterol Clenbuterol Corbadrine Denopamine Dipivefrine Dobutamine Dopamine Dopexamine Droxidopa (L-DOPS) Ephedrine Epinephrine Etafedrine Etilefrine Etilevodopa Ethylnorepinephrine Fenoterol Formoterol Hexoprenaline Higenamine Indacaterol Isoetarine Isoprenaline Isoxsuprine L-DOPA (levodopa) L-Phenylalanine L-Tyrosine Levosalbutamol Mabuterol Melevodopa Methoxyphenamine Methyldopa Mirabegron Norepinephrine Orciprenaline Oxyfedrine PF-610355 Phenylpropanolamine Pirbuterol Prenalterol Ractopamine Procaterol Pseudoephedrine Reproterol Rimiterol Ritodrine Salbutamol Salmeterol Solabegron Terbutaline Tretoquinol Tulobuterol Vilanterol Xamoterol XP21279 Zilpaterol Zinterol

Antagonists Acebutolol Adaprolol Adimolol Afurolol Alprenolol Alprenoxime Amosulalol Ancarolol Arnolol Arotinolol Atenolol Befunolol Betaxolol Bevantolol Bisoprolol Bopindolol Bornaprolol Brefonalol Bucindolol Bucumolol Bufetolol Bufuralol Bunitrolol Bunolol Bupranolol Butaxamine Butidrine Butofilolol Capsinolol Carazolol Carpindolol Carteolol Carvedilol Celiprolol Cetamolol Cicloprolol Cinamolol Cloranolol Cyanopindolol Dalbraminol Dexpropranolol Diacetolol Dichloroisoprenaline Dihydroalprenolol Dilevalol Diprafenone Draquinolol Ecastolol Epanolol Ericolol Ersentilide Esatenolol Esprolol Eugenodilol Exaprolol Falintolol Flestolol Flusoxolol Hydroxycarteolol Hydroxytertatolol ICI-118,551 Idropranolol Indenolol Indopanolol Iodocyanopindolol Iprocrolol Isoxaprolol Isamoltane Labetalol Landiolol Levobetaxolol Levobunolol Levomoprolol Medroxalol Mepindolol Metipranolol Metoprolol Moprolol Nadolol Nadoxolol Nebivolol Nifenalol Nipradilol Oxprenolol Pacrinolol Pafenolol Pamatolol Pargolol Penbutolol Pindolol Practolol Primidolol Procinolol Pronethalol Propafenone Propranolol Ridazolol Ronactolol Soquinolol Sotalol Spirendolol SR 59230A Sulfinalol Talinolol Tazolol Tertatolol Tienoxolol Tilisolol Timolol Tiprenolol Tolamolol Toliprolol Xibenolol Xipranolol

See also: Dopaminergics

Melatonergics

Serotonergics

Monoamine reuptake and release modulators

Monoamine metabolism modulators

Monoamine neurotoxins

Monoamine metabolism modulators

Common
(non-specific)

AAAD

MAO

Inhibitors: Non-selective: Benmoxin Caroxazone Echinopsidine Furazolidone Guineesine Hydralazine Indantadol Iproclozide Iproniazid Isocarboxazid Isoniazid Linezolid Mebanazine Metfendrazine Nialamide Octamoxin Paraxazone Phenelzine Pheniprazine Phenoxypropazine Pivhydrazine Procarbazine Safrazine Tranylcypromine

Inhibitors: MAO-A-selective: Amiflamine Bazinaprine Befloxatone Brofaromine Cimoxatone Clorgiline CX157 (Tyrima) Eprobemide Esuprone Harmala alkaloids (e.g., harmine, harmaline, harman, norharman, tetrahydroharmine) Methylene blue Metralindole Minaprine Moclobemide Pirlindole Sercloremine Tetrindole Toloxatone

Inhibitors: MAO-B selective: Almoxatone D-Deprenyl Ethanol Ladostigil Lazabemide Milacemide Mofegiline Nicotine Pargyline^‡ Rasagiline Safinamide Selegiline (L-Deprenyl)

Phenethylamines
(dopamine, epinephrine,
norepinephrine)

PAH	Inhibitors: 3,4-Dihydroxystyrene

TH	Inhibitors: 2-Hydroxyestradiol 2-Hydroxyestrone 3-Iodotyrosine Aquayamycin Bulbocapnine Metirosine Oudenone

DBH	Inhibitors: Bupicomide Disulfiram Dopastin Fusaric acid Nepicastat Phenopicolinic acid Tropolone

PNMT	Inhibitors: CGS-19281A SKF-64139 SKF-7698

COMT	Inhibitors: 2-Hydroxyestradiol 2-Hydroxyestrone Entacapone Nitecapone Tolcapone

Tryptamines
(serotonin, melatonin)

TPH	Inhibitors: AGN-2979 Fenclonine (PCPA) Telotristat

See also: Adrenergics • Dopaminergics • Melatonergics • Serotonergics • Monoamine reuptake and release modulators • Monoamine neurotoxins

Phenethylamines

Phenethylamines	Psychedelics: 25B-NBOMe 25C-NBOMe 25D-NBOMe 25I-NBOMe 25N-NBOMe 2C-B 2C-B-AN 2C-B-FLY βk-2C-B 2C-C 2C-D 2C-E 2C-EF 2C-F 2C-G 2C-I 2C-N 2C-P 2C-SE 2C-T 2C-T-2 2C-T-4 2C-T-7 2C-T-8 2C-T-9 2C-T-13 2C-T-15 2C-T-16 2C-T-17 2C-T-21 2C-TFM 2C-YN Allylescaline DESOXY Escaline Isoproscaline Jimscaline Macromerine MEPEA Mescaline Metaescaline Methallylescaline Proscaline Psi-2C-T-4 TCB-2 Stimulants: Phenylethanolamine Hordenine Phenethylamine α-Methylphenethylamine (amphetamine) β-Methylphenethylamine m-Methylphenethylamine N-Methylphenethylamine o-Methylphenethylamine p-Methylphenethylamine Entactogens: Lophophine MDPEA MDMPEA Others: BOH DMPEA

Amphetamines	Psychedelics: 3C-BZ 3C-E 3C-P Aleph Beatrice Bromo-DragonFLY D-Deprenyl DMA DMCPA DMMDA DOB DOC DOEF DOET DOI DOM DON DOPR DOTFM Ganesha MMDA MMDA-2 Psi-DOM TMA TeMA Stimulants: 2-FA 2-FMA 3-FA 3-FMA Acridorex Alfetamine Amfecloral Amfepentorex Amphetamine (Dextroamphetamine, Levoamphetamine) Amphetaminil Benfluorex Benzphetamine Cathine Clobenzorex Dimethylamphetamine Ephedrine Etilamfetamine Fencamfamine Fencamine Fenethylline Fenfluramine (Dexfenfluramine, Levofenfluramine) Fenproporex Flucetorex Fludorex Formetorex Furfenorex Gepefrine 4-Hydroxyamphetamine Iofetamine Isopropylamphetamine Lefetamine Lisdexamfetamine Mefenorex Metaraminol Methamphetamine (Dextromethamphetamine, Levomethamphetamine) Methoxyphenamine MMA Morforex Norfenfluramine L -Norpseudoephedrine N,alpha-Diethylphenylethylamine Oxifentorex Oxilofrine Ortetamine PBA PCA Phenpromethamine PFA PFMA PIA PMA PMEA PMMA Phenylpropanolamine Pholedrine Prenylamine Propylamphetamine Pseudoephedrine Sibutramine Tiflorex Tranylcypromine Xylopropamine Zylofuramine Entactogens: 4-FA 4-FMA 4-MA 4-MMA 4-MTA 5-APB 5-APDB 5-EAPB 5-IT 5-MAPB 5-MAPDB 6-APB 6-APDB 6-Chloro-MDMA 6-EAPB 6-IT 6-MAPB 6-MAPDB EDA IAP 2,3-MDA 3,4-MDA MDEA MDHMA MDMA MDOH Methamnetamine MMDMA Naphthylaminopropane TAP Others: 3,4-DCA Amiflamine DFMDA Selegiline (also D -Deprenyl)

Phentermines	Stimulants: Chlorphentermine Cloforex Clortermine Etolorex Mephentermine Pentorex Phentermine Entactogens: MDPH MDMPH Others: Cericlamine

Cathinones	Stimulants: 3-FMC 4-MC 4-BMC 4-CMC 4-EMC 4-FMC 4-MEC 4-MeMABP 4-MPD Amfepramone Benzedrone Brephedrone Buphedrone Bupropion Cathinone Dimethylcathinone Ethcathinone Eutylone Hydroxybupropion Methcathinone Methedrone NEB Pentedrone Pentylone Radafaxine Entactogens: 3,4-DMMC 3-MMC Butylone Ethylone Methylone Methylenedioxycathinone Mephedrone

Phenylisobutylamines	Entactogens: 4-CAB 4-MAB Ariadne BDB Butylone EBDB Eutylone MBDB Stimulants: Phenylisobutylamine

Phenylalkylpyrrolidines	Stimulants: α-PBP α-PHP α-PPP α-PVP MDPBP MDPPP MDPV 4-MePBP 4-MePHP 4-MePPP MOPPP MOPVP MPBP MPHP MPPP Naphyrone PEP Prolintane Pyrovalerone

Catecholamines (and close relatives)	6-FNE 6-OHDA a-Me-DA a-Me-TRA Adrenochrome Ciladopa D -DOPA (Dextrodopa) Dimetofrine Dopamine Epinephrine Epinine Etilefrine Ethylnorepinephrine Fenclonine Ibopamine Isoprenaline Isoetarine L -DOPA (Levodopa) L -DOPS (Droxidopa) L -Phenylalanine L -Tyrosine m-Tyramine Metanephrine Metaraminol Metaterol Metirosine Methyldopa N,N-Dimethyldopamine Nordefrin (Levonordefrin) Norepinephrine Norfenefrine (m-Octopamine) Normetanephrine Orciprenaline p-Octopamine p-Tyramine Phenylephrine Synephrine

Miscellaneous	AL-LAD Amidephrine Arbutamine Cafedrine Denopamine Desvenlafaxine Diphenidine Dizocilpine Dobutamine Dopexamine Ephenidine Etafedrine ETH-LAD Famprofazone Fluorolintane Hexapradol IP-LAD Lysergic acid amide Lysergic acid 2-butyl amide Lysergic acid 2,4-dimethylazetidide Lysergic acid diethylamide Methoxamine Methoxphenidine MT-45 PARGY-LAD Phenibut PRO-LAD Pronethalol Salbutamol (Levosalbutamol) Theodrenaline Thiamphenicol UWA-101

This article is issued from Wikipedia - version of the 9/2/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.