Year: 2026

Introduction Definition and Overview Prazosin is a selective antagonist of the alpha‑1 (α1) adrenergic receptors, predominantly acting on the peripheral vasculature. By competitively inhibiting receptor binding, it induces vasodilation, thereby reducing systemic vascular resistance and blood pressure. The drug is available in immediate‑release and extended‑release formulations, with dosing typically ranging from 1 to 8 mg per…

Introduction Definition and Overview Scopolamine is a naturally occurring tropane alkaloid derived from members of the Solanaceae family, particularly Hyoscyamus niger and Datura stramonium. It functions primarily as a non-selective antagonist of muscarinic acetylcholine receptors (mAChRs), thereby inhibiting parasympathetic neurotransmission in both central and peripheral tissues. The drug is commercially available in oral tablets, transdermal…

Introduction Atropine is a naturally occurring tropane alkaloid that has been employed therapeutically for over a century. It functions primarily as a competitive antagonist of muscarinic acetylcholine receptors, thereby modulating the parasympathetic nervous system. Historically, atropine was first isolated from the leaves of Atropa belladonna in the 18th century, and its clinical utility has expanded…

Introduction Organophosphates (OPs) constitute a class of organometallic compounds characterized by a phosphorus atom bonded to at least one oxygen, nitrogen, or carbon atom. These molecules encompass a wide range of chemicals, including pesticides, chemical warfare agents, and certain therapeutic agents. Their notoriety is largely tied to their potent inhibition of acetylcholinesterase (AChE), leading to…

Introduction Neostigmine is a well‑established anticholinesterase agent used predominantly to reverse neuromuscular blockade and to manage myasthenic crises. It functions by competitively inhibiting acetylcholinesterase (AChE), thereby increasing the concentration of acetylcholine (ACh) at synaptic junctions. The clinical significance of neostigmine has been recognized since the mid‑twentieth century, when the discovery of organophosphates highlighted the therapeutic…

Introduction Pilocarpine is a synthetic derivative of the natural alkaloid muscarine, classified as a non‑selective muscarinic acetylcholine receptor agonist. It has been employed for more than a century in both ophthalmic and systemic therapeutic contexts, primarily to stimulate parasympathetic activity. The drug’s ability to induce ciliary muscle contraction, reduce intra‑ocular pressure, and increase salivary secretion…

Introduction Acetylcholine (ACh) represents the most extensively studied endogenous neurotransmitter within the autonomic and central nervous systems. As a small quaternary amine, it mediates rapid excitatory and modulatory signaling through its interaction with two principal classes of receptors: nicotinic acetylcholine receptors (nAChRs) and muscarinic acetylcholine receptors (mAChRs). Initial discovery of ACh as a neurotransmitter dates…

Introduction Dopamine is a catecholamine neurotransmitter and hormone that plays a pivotal role in numerous physiological processes, including motor control, reward pathways, cardiovascular regulation, and endocrine function. Its discovery in the early 20th century and subsequent elucidation as a key neurotransmitter in the basal ganglia marked a turning point in neuropharmacology. The present monograph aims…

Introduction Definition and Overview Noradrenaline, also referred to as norepinephrine, is a catecholamine neurotransmitter and hormone that plays a pivotal role in the sympathetic nervous system. It exerts its effects through binding to adrenergic receptors, thereby modulating cardiovascular, neurological, and endocrine functions. The molecule is synthesized from the amino acid tyrosine via a well-characterized enzymatic…

Introduction Adrenaline, also known as epinephrine, is a pivotal endogenous catecholamine and exogenous drug that exerts profound effects on the cardiovascular, respiratory, and metabolic systems. Historically isolated from the adrenal medulla in the 19th century, it has become indispensable in acute medical interventions such as anaphylaxis, cardiac arrest, and severe asthma exacerbations. The present chapter…