通过可逆衰变来直接交换制药中的碳同位素

Enterohepatic cycling involves the active secretion of drugs and their metabolites into the bile via transporters in the canalicular membrane of hepatocytes. This secretion is an integral part of the digestive process, releasing these substances into the gastrointestinal (GI) tract.
Post-release drugs and metabolites can be reabsorbed into the body from the intestine. For conjugated metabolites like glucuronides, reabsorption requires enzymatic hydrolysis by intestinal microflora. This...

Oxidative reactions are pivotal in metabolizing numerous compounds, including pharmaceutical drugs. These reactions often occur in carbon-heteroatom systems, such as carbon-nitrogen, carbon-sulfur, and carbon-oxygen.
In carbon-nitrogen systems, aliphatic and aromatic amines can undergo oxidative reactions. Secondary and tertiary amines, like those found in tricyclic antidepressants, can undergo N-dealkylation, a process that involves the oxidation of the alkyl group. In addition, oxidative...

Phase I biotransformation reductive reactions are chemical processes that modify drugs by introducing or revealing polar functional groups via reduction. Enzymes called reductases catalyze these reactions, playing a pivotal role in drug metabolism by transforming lipophilic drugs into more polar, water-soluble metabolites for easy excretion. An essential type of reductive reaction is the carbonyl group reduction, where aldehydes and ketones are reduced to alcohols. An example is the...

Conjugation, a key component of phase II biotransformation reactions, is a vital process in drug detoxification. It involves transferring endogenous substances like glucuronic acid, sulfate, and glycine to drugs or their metabolites formed in phase I reactions. These conjugation reactions, often catalyzed by specific enzymes, transform potentially harmful metabolites into inactive, water-soluble forms easily excreted in urine or bile. By enhancing polarity and eliminating pharmacological...

Pharmaceutical substances known as xenobiotics are predominantly lipophilic and nonionized. This enables them to permeate lipid bilayers, such as cell membranes, and interact with intracellular target receptors. Lipophilic drugs have an advantage in crossing biological barriers and reaching their intended sites of action. However, lipophilic drugs often have a restricted capacity for renal expulsion or elimination from the body. When these drugs enter the kidneys and undergo glomerular...

Biotransformation, also known as drug metabolism, is a vital physiological process that chemically alters drugs, facilitating their elimination from the body and terminating their action. This process involves two main phases: phase I and phase II reactions. Phase I reactions, including oxidation, reduction, and hydrolysis, introduce or unmask polar functional groups on the drug molecule, thereby increasing its water solubility. By enhancing water solubility, the drug becomes more hydrophilic...