Drug metabolism is the chemical alteration of a drug by the body. (See also Introduction to Administration and Kinetics of Drugs.) Some drugs are chemically altered by the body (metabolized).
What can alter drug metabolism?
Physiological factors that can influence drug metabolism include age, individual variation (e.g., pharmacogenetics), enterohepatic circulation, nutrition, intestinal flora, or sex differences. In general, drugs are metabolized more slowly in fetal, neonatal and elderly humans and animals than in adults.
What does metabolism mean in medication?
Drug metabolism is the term used to describe the biotransformation of pharmaceutical substances in the body so that they can be eliminated more easily. The majority of metabolic processes that involve drugs occur in the liver, as the enzymes that facilitate the reactions are concentrated there.
What are the four stages of drug metabolization?
The four stages are absorption, distribution, metabolism, and excretion.
What are the two categories 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 organ is responsible for 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.
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 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 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.
What are the consequences of drug metabolism?
In general, the metabolism of a drug decreases its therapeutic effect. The majority of drugs are metabolized to increase their water solubility to allow elimination in urine or bile. However some drugs are metabolized into active compounds first before subsequent metabolism to inactive compounds and be excreted.
What are the 5 ways drugs can enter your body?
For example, there are five methods of drug abuse which allow drugs to enter the body: swallowing, smoking, snorting, through suppositories and injecting.
What drug does to the body is called?
Pharmacodynamics, described as what a drug does to the body, involves receptor binding, postreceptor effects, and chemical interactions. Drug pharmacokinetics determines the onset, duration, and intensity of a drug’s effect.
How do drugs exit the body?
While drugs and their metabolites are mostly excreted by the kidneys into urine, drugs can also leave the body in other methods, such as breath and sweat, hence the noticeable smell of alcohol on someone who has been drinking very heavily.
What is first pass metabolism of drug?
The first-pass metabolism or the first-pass effect or presystemic metabolism is the phenomenon which occurs whenever the drug is administered orally, enters the liver, and suffers extensive biotransformation to such an extent that the bioavailability is drastically reduced, thus showing subtherapeutic action (Chordiya …
What is the main purpose of drug metabolism?
Drugs can be metabolized by oxidation, reduction, hydrolysis, hydration, conjugation, condensation, or isomerization; whatever the process, the goal is to make the drug easier to excrete. The enzymes involved in metabolism are present in many tissues but generally are more concentrated in the liver.
Why does first pass metabolism occur?
The drug is absorbed from the GI tract and passes via the portal vein into the liver where some drugs are metabolised. … For example, first pass metabolism occurs in the gut for benzylpenicillin and insulin and in the liver for propranolol, lignocane, chloromethiasole and GTN.