Pharmacokinetics in Patient Care Quiz

The study of how the body affects a drug, including absorption, distribution, metabolism, and elimination.

The effect of a drug on the body, including both desired clinical effects and potential side effects.

The process by which a drug enters the bloodstream.

The percentage of a drug that reaches the bloodstream after administration.

Movement of molecules from an area of high concentration to low concentration.

This method of drug transport requires energy to move molecules across cell membranes.

The reduction in drug efficacy due to metabolism by the liver before it reaches systemic circulation.

Dosage forms that allow for slow and sustained release of a drug.

The tendency of a drug to exist in its ionized form, which affects its absorption, distribution, and elimination.

The pH at which 50% of a drug exists in its ionized form and 50% in its unionized form.

An acidic environment (lower pH) favors the ionized form of basic drugs, while a basic environment (higher pH) favors the ionized form of acidic drugs.

The process of drug absorption is enhanced by the presence of a higher concentration of the unionized form of the drug.

The phenomenon where a drug's ionized form accumulates in a compartment with a different pH than its site of administration.

Ion trapping can occur when a basic drug is administered in an acidic environment, such as fetal circulation, leading to a higher concentration of the drug in the acidic compartment.

Ion trapping can contribute to drug toxicity by increasing the concentration of the drug in a specific tissue or organ.

The ionized form of a drug is hydrophilic, water-soluble, and less likely to cross membranes.

The unionized form of a drug is lipophilic, fat-soluble, and more readily crosses membranes.

The process of a drug moving from its site of administration to its target site.

The process by which the body eliminates a drug, including metabolism and excretion.

The ability of a drug to reach its site of action and produce a therapeutic effect.

The concentration of a drug at its target site is influenced by its pKa and the pH of the surrounding environment.

Understanding drug ionization and pKa helps to optimize drug formulations for better absorption, distribution, and efficacy.

Ionization is the process of adding or removing a charge from a drug molecule. It happens when a drug gains or loses a hydrogen ion (H+).

Acids are proton donors, meaning they have an H+ attached and can give it away. Bases are proton acceptors, they take in the H+.

The pH of a solution determines whether a drug will be ionized or not. For example, an acidic drug will be less ionized in an acidic solution.

The pKa of a drug tells us how strongly it holds onto its hydrogen ion (H+). A lower pKa means the drug is more acidic, and will be ionized at a lower pH.

When the pH of the solution is equal to the pKa of the drug, the drug will be 50% ionized and 50% non-ionized.

The non-ionized form of a drug is more likely to pass through cell membranes because it is lipid-soluble and can easily move through the fatty layer of the cell.

Active transport requires energy to move drugs against a concentration gradient. It is crucial when a drug needs to be transported from an area of low concentration to an area of high concentration.

The non-ionized form of a drug is generally the pharmacologically active form, meaning it can interact with its target in the body to exert its effects.

The Henderson-Hasselbalch equation is used to calculate the ratio of ionized and non-ionized drug molecules in a solution at a given pH.

Most drugs are weak acids or bases, meaning they partially dissociate in solution. This means they exist in both ionized and non-ionized forms.

A weak acid will give up a proton (H+) more easily in an environment with a higher pH, because there is more base available to accept it.

Cookie Monster analogy: Think of Cookie Monster as an acid. When he gets a cookie (H+), he's non-ionized. When he loses a cookie (H+), he's ionized.

A drug's pKa is a constant that tells us how much of it will be ionized at a given pH. The lower the drug's pKa, the more acidic it is.

The pKa of a drug helps us understand how it will be absorbed, distributed, and eliminated by the body.

Drugs can have different properties depending on their ionization state. Understanding pKa helps us predict how drugs will behave in different parts of the body.

The process by which a drug moves from its administration site into the bloodstream.

The process of a drug being broken down by the liver before it reaches systemic circulation.

The process of drugs moving across cell membranes from areas of high concentration to low concentration, without energy expenditure.

The binding of a drug to proteins in the bloodstream, primarily albumin.

The competition between drugs for binding to proteins in the bloodstream, potentially affecting drug efficacy.

The dosage range of a drug that produces the desired therapeutic effect without causing toxicity.

The dosage range of a drug that causes harmful side effects.

The total amount of water in the body, divided into intracellular and extracellular compartments, which further subdivide into interstitial and plasma.

The tendency of a drug to accumulate in specific tissues or organs.

Drugs that increase the activity of enzymes involved in drug metabolism, leading to faster breakdown of the drug and potentially requiring a higher dose.

Drugs or conditions that decrease the activity of enzymes involved in drug metabolism, leading to slower breakdown and potentially higher blood levels of the drug.

The fraction of drug removed from the plasma during a single pass through an organ.

A type of drug metabolism where a fixed amount of drug is eliminated per unit of time, regardless of the drug concentration.

Elimination of drugs through the kidneys, influenced by factors like drug polarity, pH, and whether the drug is hydrophilic or lipophilic.

A type of drug metabolism where a constant fraction of drug is eliminated per unit of time, resulting in a gradual decrease in concentration.

The process by which substances in the blood are filtered into the urine filtrate.

The process of eliminating a drug from the body, usually via the kidneys, liver, intestines, or lungs.

The volume of plasma cleared of drug per unit of time, measuring the efficiency of drug removal.

The pH of the urine impacts drug excretion. Acidic urine promotes excretion of basic drugs, while basic urine promotes excretion of acidic drugs.

The fraction of drug removed from the blood as it passes through a specific organ, usually the liver.

Drugs with a high hepatic extraction ratio are mainly cleared by the liver, their clearance is dependent on blood flow.

The time it takes for the concentration of a drug in the body to reduce by half after an IV injection.

The volume of distribution is related to how much drug is distributed to the body tissues. A larger volume of distribution means that the drug is going to be distributed to more areas of the body.

Drugs with a low hepatic extraction ratio are cleared by the liver and other organs, their clearance is dependent on liver enzyme activity.

The ability of the body to clear a drug from the blood.

The concentration of a drug in the plasma (blood) changes over time due to distribution, metabolism, and excretion.

A type of drug metabolism occurring in the bloodstream, primarily by hydrolysis.

A spontaneous chemical reaction that breaks down certain drugs, dependent on pH and temperature.

A simplified model of drug distribution assuming the drug is evenly distributed throughout the body.

A more complex model of drug distribution where the drug is distributed to multiple compartments in the body.

Membrane-bound enzymes found in the liver and other organs, involved in Phase 1 metabolism.

A method of drug elimination that involves a spontaneous chemical reaction, dependent on pH and temperature.

The redistribution of a drug from the plasma to other compartments in the body over time.

A model of drug distribution that considers two compartments, usually the plasma and the tissues.

A theoretical volume that reflects the total body space that a drug would occupy if it were uniformly distributed throughout the body.

The central compartment receives a higher blood flow compared to the peripheral compartment. Examples of central compartments include the lungs and endocrine glands. The peripheral compartment encompasses skin, fat, and muscles.

Drugs tend to accumulate in the peripheral compartment, making it challenging for them to distribute back to the central compartment due to reduced blood flow.

The amount of drug given divided by the desired plasma concentration.

A larger volume of distribution indicates that a higher loading dose is required to achieve the desired plasma concentration.

Plasma concentration in the central compartment, particularly in the central nervous system, reaches its peak effect faster due to the drug's affinity for the central nervous system.

Lipophilic drugs, like propofol, have a large volume of distribution because they move freely and distribute extensively.

The volume of distribution is influenced by a number of factors, including the drug's properties, patient characteristics, and disease states.

A drug's movement across membranes is affected by several factors, including ionization, lipid solubility, molecular weight, and protein binding.

Albumin is the primary protein involved in drug binding. The degree of protein binding is influenced by albumin levels in the plasma.

The first pass effect describes the metabolism of orally administered drugs in the liver before they reach systemic circulation. This can significantly reduce the drug's bioavailability.

Phase 1 metabolism modifies the drug molecule, primarily to increase its water solubility. Phase 2 metabolism further enhances water solubility through conjugation with substrates.

Factors that affect drug diffusion across membranes include: ionization, lipid solubility, molecular weight, protein binding, concentration gradient, and membrane thickness.

The volume of distribution influences elimination. A larger volume leads to a more difficult excretion process.

Ionization is a crucial factor in drug diffusion. An ionized form is hydrophilic and less likely to cross membranes, while a non-ionized form is lipophilic and more readily crosses membranes.

A model used to describe drug distribution where the drug moves between different compartments (e.g., blood, tissues) at different rates.

The point where the rate of drug entering the body equals the rate of drug leaving the body, resulting in a stable plasma concentration.

The amount of drug needed to quickly achieve a therapeutic concentration, often given initially.

The time it takes for the plasma concentration of a drug to decrease by 50% following an IV infusion at steady state.