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 can affect drug metabolism?
Individual drug metabolism rates are influenced by genetic factors, coexisting disorders (particularly chronic liver disorders and advanced heart failure), and drug interactions (especially those involving induction or inhibition of metabolism). For many drugs, metabolism occurs in 2 phases.
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 does altering drug metabolism mean?
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).
Which factors alter drug metabolism in older adults?
Aging results in a number of significant changes in the human liver including reductions in liver blood flow, size, drug-metabolizing enzyme content, and pseudocapillarization. Drug metabolism is also influenced by comorbid disease, frailty, concomitant medicines, and (epi)genetics.
How does liver disease affect drug metabolism?
Cirrhosis causes changes in the architecture of the liver leading to changes in blood flow, protein binding, and drug metabolizing enzymes. Drug metabolizing enzymes are primarily decreased due to loss of liver tissue. However, not all enzyme activities are reduced and some are only altered in specific cases.
How does gender affect drug metabolism?
Sex differences in metabolism (phase I and II) are believed to be the major cause of differential pharmacokinetics between men and women. Many CYP450 enzymes (phase I metabolism) show a sex-dependent difference in activity. Most of the phase II enzymes have a higher activity in men than in women.
How does cyp2c19 affect metabolism?
Most often, changes in the CYP2C19 gene lead to impaired metabolism of these drugs, which reduces their effectiveness. One change in the CYP2C19 gene (known as CYP2C19*17) increases the enzyme’s ability to metabolize drugs.
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 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 the 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.
Does exercise increase drug metabolism?
Exercise reduces the blood flow in the liver and deactivation of drugs with flow-limited (high clearance) hepatic metabolism such as nitrates and lidocaine. Metabolism of capacity-limited (low clearance) drugs, e.g. antipyrine, diazepam and amobarbital, is not influenced by exercise.
What four routes are drugs excreted?
These organs or structures use specific routes to expel a drug from the body, these are termed elimination pathways:
How does weight affect drug effectiveness?
Changes in body weight can influence the amount of medicine you need to take and how long it stays in your body. The circulatory system may slow down, which can affect how fast drugs get to the liver and kidneys.
How does age affect drug response?
In general, as we age, total body water and muscle mass decrease while percentage of body fat increases. These changes can lead to drugs having a longer duration of action and increased effect. Drugs that were effective may become compounded and overexceed their therapeutic threshhold causing increased side effects.