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.
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
Parasympathetic Nervous System (PNS) Definition The Parasympathetic Nervous System (PNS) are drugs that mimic or enhance the effects. They promote “rest and digest” functions by stimulating muscarinic and nicotinic receptors, leading to effects such as reduced heart rate, increased glandular secretions, and enhanced digestive activity. Cholinergic Agonists (Parasympathomimetics) Mimic acetylcholine, stimulating the PNS. Effects: ↓ … Read more
Neurons and Synapses Definition neurons and synapses, representing the fundamental unit of neural communication where electrical or chemical signals are transmitted from one neuron to another. It emphasizes the inseparable relationship between the nerve cell (neuron) and its connection point (synapse) in processing and transmitting information within the nervous system. Neurons Neurons are the fundamental … Read more
The nervous system is a complex network of nerves and cells, known as neurons, that transmit signals between different parts of the body. It essentially functions as the body’s electrical wiring. It is divided into two main components: Central (CNS) Peripheral (PNS) This system is fundamental to everything the body does, from sensing heat and … Read more
Factors Affecting Drug Metabolism: It is influenced by biological, chemical, and stereochemical factors, affecting drug efficacy, clearance, and potential toxicity. Biological and Chemical Factors Affecting Drug Metabolism Genetic Polymorphisms Enzyme Variability: Differences in genes encoding drug-metabolizing enzymes (e.g., CYP450) lead to variations in metabolic rates. Metabolizer Phenotypes: Individuals can be poor, intermediate, extensive, or ultra-rapid … Read more
Drug Metabolism Principles Definition Drug Metabolism Principles: Drug metabolism is the biochemical modification of pharmaceutical substances in the body, primarily carried out by liver enzymes. It occurs in two main phases: Phase I Metabolism Overview: Phase I reactions modify drug molecules via oxidation, reduction, or hydrolysis, often introducing or exposing functional groups (-OH, -NH₂, -SH). Common … Read more
