Kinetics of drug elimination explains how drugs are removed from the body, following zero or first-order processes. Drug elimination kinetics describe how the concentration of a drug decreases over time. Clearance and Half-Life Clearance (CL): The volume of plasma completely cleared of drug per unit time (mL/min or L/hr). Total body clearance is the sum … Read more
Idiosyncrasy in pharmacology refers to an unusual and unpredictable drug reaction that is not dose-dependent and often genetically determined. Such drug responses vary among individuals, where most patients tolerate the medicine, but certain susceptible people may experience harmful effects. For example, Primaquine can cause hemolysis in individuals with G6PD deficiency, highlighting how genetic factors influence … Read more
Definition of Tolerance: It is a condition where increasing doses of a drug are required to produce the same effect previously achieved with a lower dose. Types: Pharmacokinetic: Due to increased drug metabolism (e.g., enzyme induction). Example: Barbiturates increase liver enzymes that metabolize drugs. Pharmacodynamic: Due to cellular changes at the receptor level (e.g., receptor … Read more
This article explains about the Addiction is a chronic disorder marked by compulsive drug use despite harmful consequences. Definition: Addiction is a chronic, relapsing disorder characterized by: Compulsive drug-seeking behavior Loss of control over drug use Continued use despite harm It is mainly psychological and involves reward pathways in the brain (dopamine system). Drugs Commonly … Read more
Tachyphylaxis is a rapid decrease in drug response after repeated doses in a short period, leading to reduced effectiveness. Definition of Tachyphylaxis: Tachyphylaxis is a rapid decrease in drug response after repeated administration in a short time. Key Features: Occurs quickly (within minutes to hours). Further dosing does not restore the effect. Mechanism: Possible depletion … Read more
Dependence is a condition in which the body adapts to continuous drug use, making the substance necessary to maintain normal physiological or psychological function. When the drug is reduced or stopped, withdrawal symptoms such as anxiety, irritability, sweating, tremors, or more severe reactions may occur. It can be physical, where the body relies on the … Read more
Spare receptors enhance drug response, allowing maximum effect even when not all receptors are occupied. Definition of Spare Receptors: Spare receptors are receptors that are not required to be occupied by a drug to produce the maximum response. Significance: A full response can be achieved even when only a small fraction of total receptors are … Read more
Antagonists are drugs that block receptor activity, preventing the action of agonists or natural ligands. Definition: An antagonist is a drug that binds to a receptor without activating it. It blocks the action of agonists (both drugs and endogenous substances). Types of Antagonists: Competitive Antagonist: Binds reversibly to the same site as the agonist on … Read more
Agonists are drugs that bind to receptors and activate them to produce a biological response. Definition: An agonist is a drug (or any chemical) that binds to a receptor and activates it, producing a biological response. Agonists mimic the action of endogenous (natural) ligands like hormones or neurotransmitters. Types of Agonists: Full Agonist: Produces maximum … Read more
Routes of drug administration determine how medicines enter the body, including oral, intravenous, inhalation, and topical methods. The route of administration affects the onset, intensity, and duration of drug action. Enteral Routes Oral (PO): Most common, safest, and convenient route. Subject to first-pass metabolism in the liver and variable absorption. Sublingual/Buccal: Absorbed through the oral … Read more
