Introduction and Overview Histamine H2 receptor antagonists, commonly referred to as H2 blockers, represent a cornerstone of pharmacologic therapy for acid‑related gastrointestinal disorders. These agents competitively inhibit histamine binding at H2 receptors located on gastric parietal cells, thereby attenuating the secretion of hydrochloric acid. The therapeutic significance of H2 antagonists is underscored by their broad…
Introduction / Overview Angiotensin receptor blockers (ARBs) represent a pivotal class of antihypertensive agents that selectively inhibit the angiotensin II type 1 (AT1) receptor. These medications are widely employed in the management of hypertension, heart failure, diabetic nephropathy, and other cardiovascular conditions. Their therapeutic relevance stems from their capacity to attenuate vasoconstriction, aldosterone secretion, and…
Introduction / Overview Cholinergic transmission constitutes a fundamental component of the autonomic nervous system (ANS), mediating a wide array of physiological processes ranging from heart rate modulation to gastrointestinal motility. The neurotransmitter acetylcholine (ACh) is released from pre‑ganglionic sympathetic, post‑ganglionic sympathetic, and parasympathetic neurons, acting on both nicotinic (nAChR) and muscarinic (mAChR) receptor families. A…
Introduction Pharmacodynamics refers to the study of the biochemical and physiological effects of drugs on the body and the mechanisms through which these effects are produced. Central to this discipline is the concept of signal transduction, the cascade of molecular events initiated by drug–receptor interactions that ultimately lead to a cellular response. Historically, the elucidation…
Introduction Definition and Overview Pharmacodynamics (PD) encompasses the study of the biochemical and physiological effects of drugs, as well as the mechanisms by which drugs exert their actions on biological systems. The field integrates concepts from molecular biology, physiology, and chemistry to explain how a compound interacts with its target, influencing cellular function and ultimately…
Introduction The Renin-Angiotensin-Aldosterone System (RAAS) is a complex and intricate hormonal system that plays a pivotal role in regulating blood pressure, fluid balance, and electrolyte homeostasis within the body. This system involves the coordinated actions of several organs, including the kidneys, liver, lungs, and adrenal glands, and is mediated by a series of hormones and…