Pharmacokinetics
Everything on Pharmacokinetics
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Question 1
What is the primary definition of pharmacokinetics?
Explanation
Pharmacokinetics primarily focuses on understanding how drugs move through the body in terms of absorption, distribution, metabolism, and excretion.
Question 2
Which factor does NOT significantly affect drug absorption?
Explanation
The color of the drug does not influence its absorption in the body, whereas solubility, pH, and route of administration do.
Question 3
What is the primary difference between drug efficacy and drug potency?
Explanation
Efficacy is defined as the maximum effect a drug can produce, while potency refers to the amount of drug required to elicit a given effect.
Question 4
Which of the following factors does NOT influence drug distribution?
Explanation
Time of day the drug is administered does not inherently affect drug distribution, unlike blood flow, protein binding, and lipophilicity.
Question 5
What is the main organ responsible for drug metabolism?
Explanation
The liver is the primary site for drug metabolism due to its rich enzyme activity and ability to process various substances.
Question 6
Which enzyme is crucial for the oxidation of drugs in the liver?
Explanation
Cytochrome P450 enzymes play a significant role in the oxidation, reduction, and hydrolysis of drugs within the liver.
Question 7
Which term describes the fraction of administered drug that reaches systemic circulation in the unchanged form?
Explanation
Bioavailability refers to the portion of a drug that enters the circulation unchanged after administration, primarily determining its therapeutic effects.
Question 8
What is the primary route of drug elimination from the body?
Explanation
Excretion is the primary means by which drugs are eliminated from the body, often through urine or bile after metabolism.
Question 9
Which of the following definitions describes 'clearance'?
Explanation
Clearance is defined as the volume of plasma from which a drug is completely removed per unit time.
Question 10
What factor does NOT typically affect the volume of distribution (Vd)?
Explanation
While body composition and plasma protein levels affect volume of distribution, the height of a patient does not directly influence it.
Question 11
Which barrier can impede drug distribution to the central nervous system?
Explanation
The blood-brain barrier is a selective barrier that restricts the passage of certain substances, including many drugs, from the bloodstream into the brain.
Question 12
What term describes the measure of drug effects produced at different doses?
Explanation
The dose-response relationship explains how the effects of a drug correlate with the amount administered.
Question 13
Which of the following factors can enhance drug metabolism in the liver?
Explanation
Smoking can induce certain cytochrome P450 enzymes in the liver, enhancing drug metabolism.
Question 14
Which process allows for the passive movement of drugs across cell membranes?
Explanation
Passive diffusion is the natural movement of drugs across cell membranes without the need for energy or assistance.
Question 15
Which physiological condition does NOT affect drug clearance?
Explanation
Eye color is not a physiological condition that affects how drugs are cleared from the body. It has no bearing on drug metabolism or excretion.
Question 16
Which form of administration has the highest bioavailability?
Explanation
The intravenous route provides 100% bioavailability since the drug directly enters systemic circulation.
Question 17
What effect does increasing drug lipophilicity have on drug distribution?
Explanation
Increased lipophilicity enhances a drug's ability to distribute into fat tissues due to better solubility in lipid environments.
Question 18
Which of the following is a primary pathway for drug elimination?
Explanation
Renal excretion is a key pathway for drug elimination as the kidneys filter out substances from the blood to form urine.
Question 19
What can lead to a decrease in a drug's clearance?
Explanation
Liver disease can impair metabolic processes, leading to decreased clearance of drugs from the system.
Question 20
Which of the following factors can significantly affect the bioavailability of a drug when considering its first-pass metabolism?
Explanation
The bioavailability of a drug is significantly influenced by the route of administration as it determines the extent and rate at which the active ingredient or active moiety is absorbed into the systemic circulation, bypassing the first-pass metabolism when administered parenterally, for example.