Related Concept Videos

Bioavailability: Overview01:13

Bioavailability: Overview

Bioavailability refers to the proportion of an unaltered drug that, after administration, enters the systemic circulation and can be distributed to the desired action site. Factors such as gastrointestinal (GI) absorption and liver biotransformation influence the bioavailability of a drug when it is administered orally. When a drug is administered intravenously, it enters the systemic circulation directly; by definition, its bioavailability is assumed to be 100%. The bioavailability of an...
Factors Influencing Bioavailability: First-Pass Elimination01:23

Factors Influencing Bioavailability: First-Pass Elimination

When a drug is taken orally, it undergoes a journey starting from the gastrointestinal (GI) tract, passing through the portal vein, reaching the liver, and finally entering the systemic circulation. This process involves the absorption of the drug across the GI tract. The liver is the primary site for metabolizing the drug, with some metabolism also occurring in the gut wall. This journey significantly reduces the quantity of the drug that reaches the systemic circulation, a phenomenon known as...
Drugs Affecting GI Tract Motility: Antimicrobials as Antidiarrheal Agents01:18

Drugs Affecting GI Tract Motility: Antimicrobials as Antidiarrheal Agents

Acute diarrhea, a common gastrointestinal disturbance, is characterized by the rapid evacuation of fluid stools, leading to an excessive weight in fluid. This condition typically arises from disorders affecting intestinal water and electrolyte transport. It can be triggered by an increased osmotic load within the intestine, excessive secretion of electrolytes and water, mucosal exudation of protein and fluid, or altered intestinal motility. The primary risks of acute diarrhea are dehydration...
Bioavailability: Overview01:17

Bioavailability: Overview

Bioavailability refers to the proportion of an administered drug that reaches the systemic circulation in its active, unaltered form. It is a crucial pharmacokinetic parameter that determines the effectiveness of a drug in achieving its intended therapeutic outcomes. The route of administration significantly influences bioavailability, with intravenous administration achieving 100% bioavailability as the drug directly enters the bloodstream. In contrast, oral administration often results in...
Pharmaceutical Alternatives: Stability-Related Therapeutic Nonequivalence01:22

Pharmaceutical Alternatives: Stability-Related Therapeutic Nonequivalence

Generic intravenous (IV) drugs are considered bioequivalent to their branded counterparts due to their 100% bioavailability upon administration. However, variations in stability among different drug products can significantly influence their therapeutic performance, even if they are pharmaceutically equivalent.Cefuroxime, a prophylactic antimicrobial, is often used as a single-dose IV injection for patients undergoing coronary artery bypass grafting surgery. A 3 g dose typically provides...
Inhibitors of Bacterial DNA Synthesis01:28

Inhibitors of Bacterial DNA Synthesis

Bacterial pathogens depend on precise and efficient DNA replication to sustain infection. Two type II topoisomerases—DNA gyrase and topoisomerase IV—are critical to this process, as they resolve DNA supercoiling and unlink chromosomes during replication. Fluoroquinolones, synthetic derivatives of quinolones, exploit this mechanism by stabilizing the transient DNA–enzyme cleavage complex, preventing strand religation, and causing lethal double-strand breaks. These antibiotics are selectively...