Citizendia

Methyldopa
Systematic (IUPAC) name
2-amino-3-(3,4-dihydroxyphenyl)-2-methyl-propanoic acid
Identifiers
CAS number555-30-6
ATC codeC02AB01
PubChem4138
DrugBankAPRD01106
Chemical data
FormulaC10H13NO4 
Mol. mass211. IUPAC Nomenclature is a system of naming Chemical compounds and of describing the science of Chemistry in general CAS registry numbers are unique numerical identifiers for Chemical compounds Polymers biological sequences mixtures and Alloys They are also referred to The Anatomical Therapeutic Chemical Classification System is used for the classification of drugs It is controlled by the WHO Collaborating Centre for Drug A section of the Anatomical Therapeutic Chemical Classification System. PubChem is a Database of chemical Molecules The system is maintained by the National Center for Biotechnology Information (NCBI a component The DrugBank database available at the University of Alberta is a unique Bioinformatics and Cheminformatics resource that combines detailed drug (i A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the The molecular mass (abbreviated m of a substance, more commonly referred to as molecular weight and abbreviated as MW, is the Mass of one 215 g/mol
Pharmacokinetic data
Bioavailabilityapproximately 50%
MetabolismHepatic
Half life105 minutes
ExcretionRenal for metabolites
Therapeutic considerations
Pregnancy cat.

a drug of choice in PIH

Legal status

℞ Prescription only

RoutesOral, IV

Methyldopa or alpha-methyldopa (brand names Aldomet, Apo-Methyldopa, Dopamet, Novomedopa) is a centrally-acting adrenergic antihypertensive medication. In Pharmacology, bioavailability is used to describe the fraction of an administered Dose of unchanged drug that reaches the Systemic circulation, one of Drug metabolism is the Metabolism of drugs, their Biochemical modification or degradation usually through specialized enzymatic systems The liver is a vital organ in the human body and is present in Vertebrates and some other animals The biological half-life of a substance is the time it takes for a substance (drug radioactive nuclide or other to lose half of its pharmacologic physiologic or radiologic activity Excretion is the process of eliminating waste products of Metabolism and other non-useful materials The kidneys are complicated organs that have numerous biological roles The pregnancy category of a pharmaceutical agent is an assessment of the risk of fetal injury due to the pharmaceutical if it is used as directed by the mother during The regulation of therapeutic goods, that is drugs and therapeutic devices, varies by jurisdiction In Pharmacology and Toxicology, a route Intravenous therapy or IV therapy is the giving of Liquid substances directly into a Vein. Antihypertensives are a class of drugs that are used in Medicine and Pharmacology to treat Hypertension (high blood pressure Its use is now deprecated following introduction of alternative safer classes of agents. However it continues to have a role in otherwise difficult to treat hypertension and pregnancy-induced hypertension.

Contents

Pharmacokinetics

Methyldopa has variable absorption from the gut of approximately 50%. It is metabolized in the intestines and liver; its metabolite alpha-methylnorepineprine acts in the brain to stimulate alpha-adrenergic receptors decreasing total peripheral resistance. In Anatomy, the intestine is the segment of the alimentary canal extending from the Stomach to the Anus and in humans and other mammals consists The liver is a vital organ in the human body and is present in Vertebrates and some other animals The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain The adrenergic receptors (or adrenoceptors) are a class of G protein-coupled receptors that are targets of the Catecholamines Adrenergic receptors Total peripheral resistance (TPR is the sum of the resistance of all peripheral vasculature in the systemic circulation It is excreted in urine. Excretion is the process of eliminating waste products of Metabolism and other non-useful materials Urine is a liquid waste product of the body secreted by the Kidneys by a process of filtration from Blood and Excreted through the Urethra.

Mechanism of action

Methyldopa, in its active metabolite form, is a central alpha-2 receptor agonist. Using methyldopa leads to alpha-2 receptor-negative feedback to sympathetic nervous system (SNS) (centrally and peripherally), allowing peripheral sympathetic nervous system (PSNS) tone to decrease. The α2 receptor is a type of Adrenergic receptor. Effect The α2 receptor has several general functions in common with other α-receptors but also The Sympathetic Nervous System ( SNS) is a branch of the Autonomic nervous system along with the Enteric nervous system and Parasympathetic nervous Such activity leads to a decrease in total peripheral resistance (TPR) and cardiac output. Total peripheral resistance (TPR is the sum of the resistance of all peripheral vasculature in the systemic circulation Cardiac output (Q is the volume of blood being pumped by the Heart, in particular by a ventricle in a minute

Rebound effect

Rebound hypertension has been reported in some cases when methyldopa has been abruptly withdrawn after extended use[1]. Rebound effect is the tendency of a Medication to when discontinued to cause a return of the Symptoms being treated more severe than before This results because the long term use of methyldopa lowers the sensitivity of presynaptic alpha 2 receptors: the release of norepinephrine (NE) from sympathetic nerve endings is modulated by NE itself acting on the presynaptic alpha 2 autoreceptors thus inhibiting its own release. Chemical synapses are specialized junctions through which Neurons signal to each other and to non-neuronal cells such as those in Muscles or Glands Norepinephrine ( INN) (abbreviated norepi or NE) or noradrenaline ( BAN) (abbreviated NA or NAd) is a The discontinuation of methyldopa removes the inhibition on NE release leading to excessive NE release from the SNS and the rebound hypertension.

History

When introduced it was a mainstay of antihypertensive therapy, but its use has declined, with increased use of other safer classes of agents. One of its important present-day uses is in the management of pregnancy-induced hypertension, as it is relatively safe in pregnancy compared to other antihypertensive drugs.

Side effects

There are many possible reported side-effects with some, whilst rare, being serious. Side effects are usually fewer if the dose is less than 1 g per day:[2]

YISSS

Footnotes

  1. ^ http://www.inchem.org/documents/pims/pharm/methyldo.htm
  2. ^ British National Formulary 45 March 2003
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