Pharmacokinetics and Drug Metabolism Quiz

Module One: Pharmacokinetics

• Pharmacokinetics is the study of how the body handles drugs.
• This includes absorption, distribution, metabolism, and excretion (ADME).
• A drug is a chemical agent that produces a biological response in the body.
• This response can be therapeutic (desirable) or adverse (undesirable).
• Medications are drugs used to prevent, cure, or treat diseases.

Pharmacology

• Pharmacology is the study of drugs.
• It encompasses how drugs are administered, where they travel in the body, and the responses they produce.
• Drugs can have both desirable (therapeutic) and undesirable (adverse) effects.

Prototype Drugs

• Prototype drugs serve as models for drug classes.
• They are well understood and have known actions and adverse effects.
• They are used to compare other drugs in the same pharmacologic class.
• Examples include Lasix (diuretics) and Penicillin (antibiotics).

Pharmacologic Classification of Drugs

• Pharmacologic classification is based on how a drug produces its effect at the molecular, tissue, or body-system level.
• It is more specific than therapeutic classification and requires understanding of biochemistry and physiology.
• Examples include calcium channel blockers, ACE inhibitors, and proton-pump inhibitors.

Drug Names

• Drugs have three names: chemical, generic, and trade.
• Chemical names describe the drug's chemical composition and structure.
• Generic names (nonproprietary) are given by the United States Adopted Name Council.
• Trade names (proprietary) are trademarks and used by manufacturers.
• Generic names should be written in lowercase and trade names in uppercase.

Application of Pharmacokinetics to Clinical Practice

• Pharmacokinetics helps understand how the body handles medications.
• It helps understand drug actions and side effects.
• It aids in understanding the obstacles faced by drugs to reach target cells.
• Drugs must travel through the bloodstream, interstitial fluid, to tissues, then through the cell membrane and intracellular organelles to exert their effect.

Pharmacokinetics (ADME)

• Pharmacokinetics is the study of what happens to a drug from administration until removal from the body.
• It involves: absorption, distribution, metabolism and excretion (ADME).
• Absorption: Rate and extent of a drug leaving its administration site.
• Distribution: Movement of a drug throughout the body. Factors include blood flow to the tissues, ability of the drug to leave the blood vessels, and ability of the drug to enter cells.
• Metabolism: Biotransformation of a drug by the liver into inactive metabolites. Metabolism can lead to the inactivation, the conversion to a more soluble form that allows excretion or creation of more active metabolites.
• Excretion: Removal of the drug and its metabolites from the body. This mainly occurs via kidneys, bile, and feces.

Absorption

• Absorption is the rate at which a drug leaves its site of administration and the extent to which absorption occurs.
• Bioavailability refers to the amount of drug absorbed into the systemic circulation.
• Bioequivalence refers to whether two drugs have similar bioavailability.
• Factors affecting absorption include route of administration, dosage formulation, food and fluids, and status of the GI absorptive surface, blood flow, stomach acidity, and GI motility.
• Different oral preparations have different absorption rates (e.g., liquids are faster, and enteric-coated tablets are slower).

Distribution

• Distribution is the transport of the drug through the body.
• Factors include blood flow to tissues, ability of the drug to leave blood vessels, ability of the drug to enter cells, and protein binding.
• Drugs bind to plasma proteins. Free (unbound) drugs can be distributed in the body and will have a pharmacologic effect.
• Distribution is faster in areas with high blood flow (like the brain, heart, liver, etc.).

Metabolism (Biotransformation)

• Metabolism is the biotransformation of a drug into an inactive metabolite, a more soluble compound, or a more potent metabolite.
• The liver is the major organ for drug metabolism.
• Metabolism changes a drug in one of three ways: inactivation, conversion to a more water soluble form for excretion, creating more active metabolites. Most important metabolic pathways are through the cytochrome P450 system (phase I) and conjugation reactions (phase II).
• The metabolism of a drug via the liver immediately after it is absorbed is called the first-pass effect.
• Drug metabolism can be affected by other drugs (inducing/inhibiting).

Elimination

• Elimination is the removal of drugs and their metabolites from the body.
• Kidneys, liver, and bowel are major organs in drug elimination.
• Biliary excretion and enterohepatic circulation are other pathways contributing to elimination.

Drug Levels

• Half-life: Time it takes for half of the drug to be removed from the body (a measure of drug removal rate).
• Loading Dose: Higher initial dose to quickly reach a therapeutic level.
• Maintenance Dose: Dose given repeatedly in order to maintain the therapeutic drug level.
• Drug concentration over time can be depicted in a drug response curve. This shows onset, peak, and duration, as well as minimum effective concentrations (MEC) and toxic concentrations.

Disease and Drugs

• Disease states can impact drug pharmacokinetics.
• Factors like impaired liver function, impaired kidney function, and reduced blood flow will impact drug absorption, distribution, metabolism, or excretion.
• Appropriate drug doses or frequencies may need adjustments.

Test your knowledge on pharmacokinetics, drug metabolism, and biotransformation processes. This quiz covers key concepts such as the effects of protein binding, liver function, and the importance of drug classifications. Prepare to explore various aspects of drug interactions and pharmacological definitions.