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 routes 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
Definition of Essential Drugs Concept Essential drugs (or essential medicines) are those that: Satisfy the priority health care needs of the population. Should be available at all times, in adequate amounts, appropriate dosage forms, with assured quality and affordable cost. WHO Model List of Essential Medicines (EML) First published in 1977 with 208 drugs. Updated … Read more
Membrane Transport of Drugs involves processes like passive diffusion, facilitated diffusion, active transport, and endocytosis for drug movement across cell membranes. Membrane Transport of Drugs Understanding how drugs cross biological membranes is crucial to all processes of pharmacokinetics (ADME). Biological membranes are primarily lipid bilayers interspersed with proteins. Several mechanisms allow drugs to traverse these … Read more
Source of Drugs includes natural, synthetic, and biotechnological origins such as plants, animals, minerals, and microorganisms. Drugs can be obtained from various natural, semi-synthetic, synthetic, and biotechnological sources. Natural Source of Drugs These are substances directly obtained from nature – plants, animals, microorganisms, or minerals. Plant Sources Many traditional and modern medicines originate from plants. … Read more
Nature of Drugs refers to the physical, chemical, and biological properties of drugs that determine their action, effectiveness, and therapeutic use. Definition of a Drug: A drug is any substance (natural or synthetic) that, when administered to a living organism, produces a biological effect. Drugs are used for diagnosis, prevention, treatment, or cure of diseases. … Read more
