Medicinal Chemistry I is a core subject that explores the design, synthesis, and biological activity of drugs. It bridges organic chemistry and pharmacology to enhance understanding of therapeutic agents.
Clonidine is a medication primarily used to treat high blood pressure (hypertension). It belongs to a class of drugs known as centrally acting alpha-2 adrenergic agonists. Clonidine works by stimulating alpha-2 receptors in the brain, which reduces sympathetic outflow from the central nervous system. Chemical Structure & Formula Chemical Formula: C₉H₉Cl₂N₃ Structure: Mechanism of Action … Read more
Methyldopa is an antihypertensive medication primarily used to treat high blood pressure (hypertension), especially during pregnancy. It is a centrally acting alpha-2 adrenergic agonist that works by stimulating receptors in the brain to reduce sympathetic nerve signals, leading to a decrease in blood vessel constriction and heart rate, thereby lowering blood pressure. Chemical Structure & … Read more
Dopamine is a chemical messenger, or neurotransmitter, produced in the brain that plays a key role in regulating mood, motivation, reward, attention, and movement. It helps transmit signals between nerve cells and is involved in both physical and emotional responses. Chemical Structure & Formula Chemical Formula: C₈H₁₁NO₂ Structure: Mechanism of Action (Detailed) Dopamine acts on … Read more
Phenylephrine is a selective α<sub>1</sub>-adrenergic receptor agonist commonly used as a decongestant, vasopressor, and mydriatic agent. It works by stimulating α<sub>1</sub>-receptors, leading to vasoconstriction, which reduces nasal congestion and increases blood pressure. Chemical Structure & Formula Chemical Formula: C₉H₁₃NO₂ Structure: Mechanism of Action (Detailed) Selective α1 agonist → Causes vasoconstriction. Increases blood pressure without affecting … Read more
Structure-Activity Relationship mimic catecholamines (epinephrine, norepinephrine, dopamine) by stimulating adrenergic receptors (α and β). Their activity depends on structural modifications affecting receptor selectivity, metabolism, and CNS penetration. Key Structure-Activity Relationship Features Catechol Ring Substitutions 3,4-Dihydroxy (Catechol): High α/β activity, rapid metabolism (e.g., Epinephrine, Norepinephrine). Single Hydroxyl (-OH) Group: Reduces metabolism, increases α1 selectivity (e.g., Phenylephrine). No … Read more
Sympathomimetic Agents the actions of endogenous catecholamines. They are broadly classified into three groups based on their mechanism of action: Classification of Sympathomimetic Agents Sympathomimetic agents are drugs that mimic the actions of the sympathetic (adrenergic) nervous system. They are classified based on their mechanism of action in activating adrenergic receptors. 1. Direct-Acting Sympathomimetics Mechanism: These … Read more
Adrenergic receptors are G-protein-coupled receptors (GPCRs) that mediate the effects of norepinephrine and epinephrine. Adrenergic receptors are classified into Alpha (α) and Beta (β) receptors, with further subtypes. Alpha-Adrenergic Receptors (α-Receptors) These receptors mainly mediate vasoconstriction and smooth muscle contraction. α1-Receptors (Gq-coupled) Mechanism: Activate phospholipase C (PLC) → Increase IP3 & DAG → Increase intracellular … Read more
Catecholamines are degraded primarily by Monoamine Oxidase (MAO) and Catechol-O-Methyltransferase (COMT) into inactive metabolites, which are excreted in urine. Steps of Catecholamines Catabolism MAO Pathway: MAO (located in neuronal mitochondria) oxidizes catecholamines into dihydroxyphenylglycol aldehyde. This is further converted into vanillylmandelic acid (VMA) for excretion. COMT Pathway: COMT methylates catecholamines to form metanephrine and normetanephrine. … Read more
Catecholamines Biosynthesis (dopamine, norepinephrine, and epinephrine) are synthesized from tyrosine in adrenergic neurons and the adrenal medulla. Steps of Catecholamines Biosynthesis Tyrosine Transport & Hydroxylation: Tyrosine, derived from diet or synthesized from phenylalanine, is transported into neurons. Tyrosine hydroxylase (TH) converts tyrosine into L-DOPA (Rate-limiting step). Decarboxylation to Dopamine: DOPA decarboxylase converts L-DOPA into dopamine. … Read more
Sympathetic Nervous System (SNS) Definition The Sympathetic Nervous System (SNS) is a division of the autonomic nervous system responsible for the “fight or flight” response. Drugs acting on the SNS either stimulate (sympathomimetics) or inhibit (sympatholytic) its activity by targeting adrenergic receptors (α and β), affecting heart rate, blood pressure, bronchodilation, and metabolic processes. Adrenergic … Read more
