Intestinal absorption After ingestion of a drug, the active ingredient must first be released. This process is called release (liberation), and it is a prerequisite for subsequent absorption. Absorption (formerly: resorption) is the passage of an active pharmaceutical ingredient from the digestive pulp into the bloodstream in the stomach and intestines. Absorption occurs primarily in … Absorption
Definition Pharmaceutical agents are excreted primarily in the urine and, via the liver, in the bile in the stool. When excreted via the bile, they re-enter the small intestine, where they may be reabsorbed. They are transported back to the liver via the portal vein. This repetitive process is called the enterohepatic circulation. It prolongs … Enterohepatic Circulation
Pharmacodynamics and pharmacokinetics. When we take a tablet, we are usually interested in its immediate effects. The drug is supposed to relieve a headache or reduce symptoms of a cold. At the same time, we may think about the possible side effects it may trigger. The desired and undesired effects that a drug exerts on … ADME
Introduction Elimination is a pharmacokinetic process that describes the irreversible removal of active pharmaceutical ingredients from the body. It is composed of biotransformation (metabolism) and excretion (elimination). The most important organs for excretion are the kidney and the liver. However, drugs can also be excreted through the respiratory tract, hair, saliva, milk, tears, and sweat. … Elimination
The effect of the first liver passage For a perorally administered pharmaceutical agent to exert its effects at the site of action, it usually must enter the systemic circulation. To do so, it must pass through the intestinal wall, the liver, and part of the circulatory system. Despite complete absorption in the intestine, the bioavailability … First-Pass Metabolism
CYP450 Cytochromes P450s are a family of enzymes that are of paramount importance in drug biotransformation. The most important isoenzymes for drug metabolism are: CYP1A1, CYP1A2 CYP2B6 CYP2C9, CYP2C19 CYP2D6 CYP2E1 CYP3A4, CYP3A5 and CYP3A7 The number after the abbreviation CYP stands for the family, the following letter for the subfamily and the last number … Cytochrome P450 (CYP)
Introduction Biotransformation is an endogenous pharmacokinetic process that leads to a change in the chemical structure of active pharmaceutical ingredients. The organism’s general goal in doing so is to make the foreign substances more hydrophilic and to direct them to excretion via the urine or stool. Otherwise, they could be deposited in the body and … Metabolism (Biotransformation)
Elimination at the kidney The kidneys, along with the liver, play a central role in the elimination of pharmaceutical agents. They can be filtered at the glomerulus of the nephron, actively secreted at the proximal tubule, and reabsorbed at various tubular segments. In renal insufficiency, these processes are impaired. This may result in a renally … Dose Adjustment in Renal Insufficiency
Definition and properties When active pharmaceutical ingredients enter the bloodstream, they often bind to proteins, especially albumin, to a greater or lesser extent. This phenomenon is called protein binding, and it is reversible: drug + protein ⇌ drug-protein complex Protein binding is important, first, because only the free portion distributes to tissues and induces a … Protein Binding
Definition Distribution (distribution) is a pharmacokinetic process that begins immediately after absorption of the drug from the intestine. During this process, the drug enters the bloodstream and travels to organs, body fluids, and tissues. Distribution is necessary for the drug to reach its drug target at a sufficient concentration. For example, an antidepressant must be … Distribution
Definition and properties The administration or application of a drug refers to its use on the body. The dosage forms (drug forms) used for this purpose consist of the active ingredients and excipients. These include, for example, tablets, capsules, solutions, syrups, injectables, creams, ointments, eye drops, ear drops, and suppositories. Drugs can be liquid, semi-solid, … Administration
Definition Glucuronidation refers to an intracellular metabolic reaction in which an endogenous or exogenous substrate is conjugated to glucuronic acid. The organism thereby makes the substrates more water soluble so that they can be rapidly excreted in the urine. Glucuronidation belongs to phase II metabolism (conjugations). UDP: uridine diphosphate UGT: UDP-glucuronosyltransferase Enzymes involved Glucuronidation is … Glucuronidation
