methyldopa brands

Molecular formula: C10H13NO4

The exact mechanism of methyldopa is not fully elucidated; however, the main mechanisms of methyldopa involve its actions on alpha-adrenergic receptor and the aromatic L-amino acid decarboxylase enzyme, to a lesser extent. The sympathetic outflow is regulated by alpha (α)-2 adrenergic receptors and imidazoline receptors expressed on adrenergic neurons within the rostral ventrolateral medulla. Methyldopa is metabolized to α‐methylnorepinephrine via dopamine beta-hydroxylase activity and, consequently, alpha-methylepinephrine via phenylethanolamine-N-methyltransferase activity. Mediating the therapeutic effects of methyldopa, α‐methylnorepinephrine and α-methylepinephrine active metabolites are agonists at presynaptic alpha-2 adrenergic receptors in the brainstem. Stimulating alpha-2 adrenergic receptors results in the inhibition of adrenergic neuronal outflow and attenuation of norepinephrine release in the brainstem. Consequently, the output of vasoconstrictor adrenergic signals to the peripheral sympathetic nervous system is reduced, leading to a reduction in blood pressure. The L-isomer of alpha-methyldopa also reduces blood pressure by inhibiting aromatic L-amino acid decarboxylase, also known as DOPA decarboxylase, which is an enzyme responsible for the syntheses of dopamine and serotonin. Inhibiting this enzyme leads to depletion of biogenic amines such as norepinephrine. However, inhibition of aromatic L-amino acid decarboxylase plays a minimal role in the blood-pressure‐lowering effect of methyldopa. METHYLDOPA...HAS HYPOTENSIVE ACTION INDEPENDENT OF ITS ANTIADRENERGIC ACTIONS; THIS IS PROBABLY PARTLY CENTRAL DEPRESSANT ACTION @ VASOMOTOR CENTER & PARTLY PERIPHERAL ACTION OF UNKNOWN MECHANISM. ... Alpha-methylnorepinephrine acts in the brain to inhibit adrenergic neuronal outflow from the brainstem, and this central effect is principally responsible for its antihypertensive action. IN CONSCIOUS RENAL HYPERTENSIVE RATS ALPHA-METHYLDOPA PRODUCED A LONG-LASTING FALL IN BLOOD PRESSURE WHICH WAS PARTIALLY ATTENUATED BY PRETREATMENT WITH NALTREXONE (5 MG/KG SC). PRETREATMENT WITH ANTISERUM TO BETA-ENDORPHIN APPLIED LOCALLY, ALSO BLOCKED THE DEPRESSOR RESPONSE. THESE RESULTS SUGGEST THAT THE FALL IN BLOOD PRESSURE OBSERVED AFTER ALPHA-METHYLDOPA AND ITS ACTIVE METABOLITE ALPHA-METHYLNORADRENALINE INVOLVES A BETA-ENDORPHIN LIKE PEPTIDE; A POSSIBLE SITE OF ACTION IS THE NUCLEUS TRACTUS SOLITARII. A REVIEW ON THE MECHANISM OF ACTION.

Source: PubChem (NCBI) · compound 38853