Product Information
Registration Status: ActiveMETHYLDOPA TABLET 125mg is approved to be sold in Singapore with effective from 1990-04-16. It is marketed by DRUG HOUSES OF AUSTRALIA PTE LTD, with the registration number of SIN04107P.
This product contains Methyldopa 125mg in the form of TABLET, FILM-COATED. It is approved for ORAL use.
This product is manufactured by DRUG HOUSES OF AUSTRALIA PTE LTD in SINGAPORE.
It is a Prescription Only Medicine that can only be obtained from a doctor or a dentist, or a pharmacist with a prescription from a Singapore-registered doctor or dentist.
Description
An alpha-2 adrenergic agonist that has both central and peripheral nervous system effects. Its primary clinical use is as an antihypertensive agent. [PubChem]
Indication
For use in the treatment of hypertension.
Mechanism of Action
Although the mechanism of action has yet to be conclusively demonstrated, the resultant hypotensive effect is most likely due to the drug's action on the CNS. Methyldopa is converted into the metabolite, alpha-methylnorepinephrine, in the CNS, where it stimulates the central inhibitory alpha-adrenergic receptors, leading to a reduction in sympathetic tone, total peripheral resistance, and blood pressure. Reduction in plasma renin activity, as well as the inhibition of both central and peripheral norepinephrine and serotonine production may also contribute to the drug's antihypertensive effect, although this is not a major mechanism of action. This is done through the inhibition of the decarboxylation of dihydroxyphenylalanine (dopa)—the precursor of norepinephrine—and of 5-hydroxytryptophan (5-HTP)—the precursor of serotonin—in the CNS and in most peripheral tissues.
Pharmacokinetics
- Absorption
- Absorption from the gastrointestinal tract is variable but averages approximately 50%.
- Distribution
- Metabolism
- Hepatic, extensively metabolized. The known urinary metabolites are: a-methyldopa mono-0-sulfate; 3-0-methyl-a-methyldopa; 3,4-dihydroxyphenylacetone; a-methyldopamine; 3-0-methyl-a-methyldopamine and their conjugates.
- Elimination
Clearance
* Renal cl=130 mL/min [healthy]
Toxicity
The oral LD50 of methyldopa is greater than 1.5 g/kg in both the mouse and the rat. Symptoms of overdose include bloating, constipation, diarrhea, dizziness, extreme drowsiness, gas, light-headedness, nausea, severely low blood pressure, slow heartbeat, vomiting, and weakness.
Active Ingredient/Synonyms
(S)-(-)-alpha-Methyldopa | 3-Hydroxy-alpha-methyl-L-tyrosine | Alpha medopa | alpha-Methyl dopa | alpha-methyl-L-dopa | Alphamethyldopa | AMD | Anhydrous methyldopa | L-alpha-Methyldopa | L-Methyl Dopa | Methyl dopa | Methyldopa anhydrous | α-Methyl dopa | α-methyl-L-dopa | Methyldopa |
Source of information: Drugbank (External Link). Last updated on: 3rd July 18. *Trade Name used in the content below may not be the same as the HSA-registered product.