The purpose of metabolism in the body is usually to change the chemical structure of the substance, to increase the ease with which it can be excreted from the body. Drugs are metabolized through various reactions including: Oxidation.
How does metabolism affect drugs?
Most drugs must pass through the liver, which is the primary site for drug metabolism. Once in the liver, enzymes convert prodrugs to active metabolites or convert active drugs to inactive forms.
Why is drug biotransformation necessary?
Biotransformation also serves as an important defense mechanism since toxic xenobiotics and body wastes are converted into less harmful substances and substances that can be excreted from the body. … Hydrophilic chemicals are easier for the body to eliminate than lipophilic substances .
Why is it important to understand the intended processes of drug metabolism as a therapist?
Understanding these processes is extremely important for prescribers because they form the basis on which the optimal dose regimen is chosen and explain the majority of the inter-individual variation in the response to drug therapy.
What is drug metabolism in medicinal chemistry?
Drug metabolism is the chemical alteration of a drug via a biological system to aid its elimination by increasing its hydrophilicity. … Since drug metabolism is mediated by enzymes, there is potential for natural variability and for co-administered drugs to interact, either by enzyme inhibition or induction.
What causes slow drug metabolism?
Underlying health conditions can also influence your drug metabolic rate. Some concerning ones are chronic liver disorders, kidney dysfunction, or advanced heart failure. Drug and Food Interactions. CYP450 enzymes can be impacted by the foods you eat and other drugs you take.
What are the phases of drug metabolism?
Drug metabolism reactions comprise of two phases: Phase I (functionalization) reactions such as oxidation, hydrolysis; and Phase II (conjugation) reactions such as glucuronidation, sulphate conjugation. Oxidation reactions are the most common and vital.
What is first pass metabolism of drug?
The drug is absorbed from the GI tract and passes via the portal vein into the liver where some drugs are metabolised. Sometimes the result of first pass metabolism means that only a proportion of the drug reaches the circulation. First pass metabolism can occur in the gut and the liver.
What is the difference between Phase 1 and Phase 2 metabolism?
Phase I reactions of drug metabolism involve oxidation, reduction, or hydrolysis of the parent drug, resulting in its conversion to a more polar molecule. Phase II reactions involve conjugation by coupling the drug or its metabolites to another molecule, such as glucuronidation, acylation, sulfate, or glicine.
What is metabolism in toxicology?
Metabolism or biotransformation of toxicants by the body is an “attempt to detoxify.” In some instances, metabolized xenobiotic agents are more toxic than the original compound. These reactions, catalyzed by hepatic enzymes, generally convert foreign compounds to derivatives for Phase II reactions. …
What are the 3 phases of drug action?
Drug action usually occurs in three phases: Pharmaceutical phase. Pharmacokinetic phase. Pharmacodynamic phase.
What are the four stages of drug metabolization?
The method by which a drug is administered, along with other factors, determines the speed of onset of effects. Drugs undergo four stages within the body: absorption, distribution, metabolism, and excretion.
What is oxidation in drug metabolism?
In most cases, an oxygen atom is retained in the metabolite, although some reactions, such as dealkylation, result in loss of the oxygen atom in a small fragment of the original molecule. Oxidation reactions are catalysed by a diverse group of enzymes, of which the cytochrome P450 system is the most important.
What are the sites of drug metabolism?
Most drugs must pass through the liver, which is the primary site for drug metabolism. Once in the liver, enzymes convert prodrugs to active metabolites or convert active drugs to inactive forms. The liver’s primary mechanism for metabolizing drugs is via a specific group of cytochrome P-450 enzymes.
What are the factors affecting metabolism?
Your metabolic rate is influenced by many factors – including age, gender, muscle-to-fat ratio, amount of physical activity and hormone function.
How are drugs excreted from the body?
Most drugs (or metabolites) are excreted by the kidneys. Three process can occur in renal excretion: glomerular filtration, tubular secretion and passive reabsorption. Some drugs are eliminated by the liver in the bile and excreted in feces.