Pharmacokinetics Practice Questions

80 multiple-choice questions on Pharmacokinetics for paramedic and EMT students, from Chapter 13 (Principles of Pharmacology). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

80 practice questions

1. Pharmacokinetics describes:

   1. A. How drugs bind to their receptors
   2. B. What the drug does to the body
   3. C. What the body does to the drug
   4. D. How drugs interact with each other
   Show answer

   Answer: C. What the body does to the drug

   Pharmacodynamics is the reverse relationship. It covers absorption, distribution, metabolism, and excretion.

2. Absorption refers to:

   1. A. Removal of the drug from the body by the kidneys
   2. B. Breakdown of the drug by liver enzymes
   3. C. Binding of the drug to target receptors
   4. D. Movement of the drug into the bloodstream
   Show answer

   Answer: D. Movement of the drug into the bloodstream

   The route chosen largely determines absorption speed. Absorption is movement from the site of administration into the blood.

3. Which route bypasses absorption entirely?

   1. A. Intramuscular
   2. B. Oral
   3. C. Intravenous
   4. D. Subcutaneous
   Show answer

   Answer: C. Intravenous

   IV delivers the drug directly into the circulation, giving 100 percent bioavailability.

4. Bioavailability refers to:

   1. A. Fraction of a dose reaching circulation
   2. B. The time needed to clear half of the drug
   3. C. The total dose administered by any route
   4. D. The strength of the drug's receptor binding
   Show answer

   Answer: A. Fraction of a dose reaching circulation

   Oral drugs have lower bioavailability because of first-pass metabolism. Bioavailability is the proportion reaching systemic circulation in active form.

5. First-pass metabolism refers to:

   1. A. Kidney breakdown of drugs before they are excreted
   2. B. Binding of drugs to plasma proteins after absorption
   3. C. Excretion of the drug into bile after one pass
   4. D. Liver breakdown of oral drugs before circulation
   Show answer

   Answer: D. Liver breakdown of oral drugs before circulation

   Sublingual and rectal routes partly avoid it. Drugs absorbed from the GI tract pass through the liver before reaching systemic circulation.

6. Most drug metabolism occurs in the:

   1. A. Kidneys
   2. B. Lungs
   3. C. Spleen
   4. D. Liver
   Show answer

   Answer: D. Liver

   Hepatic impairment prolongs the effect of many drugs.

7. Most drug excretion occurs through the:

   1. A. Lungs
   2. B. Kidneys
   3. C. Liver
   4. D. Sweat glands
   Show answer

   Answer: B. Kidneys

   Renal impairment leads to accumulation and toxicity.

8. A drug's half-life is:

   1. A. The time from dose to first effect
   2. B. The total time the clinical effect lasts
   3. C. The time to eliminate half of the drug
   4. D. The time needed to reach peak effect
   Show answer

   Answer: C. The time to eliminate half of the drug

   It takes roughly five half-lives to clear a drug.

9. Drugs bound to plasma proteins are:

   1. A. More potent at their target receptors
   2. B. Excreted more quickly by the kidneys
   3. C. More active than the unbound drug fraction
   4. D. Inactive while bound to the protein
   Show answer

   Answer: D. Inactive while bound to the protein

   Drugs competing for binding sites can raise each other's free levels. Only the free fraction produces an effect.

10. Distribution of a drug is affected by:

    1. A. Half-life, clearance rate, and the dosing interval
    2. B. Blood flow, protein binding, and lipid solubility
    3. C. Gastric emptying, food, and gut pH
    4. D. The dose alone, regardless of other factors
    Show answer

    Answer: B. Blood flow, protein binding, and lipid solubility

    Poor perfusion in shock impairs distribution of IM and SC drugs. Lipid solubility and tissue barriers such as the blood-brain barrier also matter. Half-life and clearance describe elimination, and gastric emptying and gut pH govern oral absorption rather than distribution.

11. Lipid-soluble drugs cross the blood-brain barrier more easily because:

    1. A. They are smaller than other drugs
    2. B. They are mostly ionized in plasma
    3. C. They bind tightly to plasma proteins
    4. D. Cell membranes are made of lipids
    Show answer

    Answer: D. Cell membranes are made of lipids

    This is why fentanyl acts on the brain so quickly.

12. In shock, the preferred route for emergency medications is:

    1. A. Intravenous or intraosseous
    2. B. Intramuscular into the deltoid
    3. C. Subcutaneous injection
    4. D. Sublingual or buccal
    Show answer

    Answer: A. Intravenous or intraosseous

    Poor peripheral perfusion makes IM and SC absorption unreliable.

13. Enteral routes include:

    1. A. Intravenous, intramuscular, and IO
    2. B. Oral, sublingual, buccal, and rectal
    3. C. Inhaled, intranasal, and nebulized
    4. D. Transdermal, topical, and intradermal
    Show answer

    Answer: B. Oral, sublingual, buccal, and rectal

    Enteral means through the GI tract.

14. Parenteral routes include:

    1. A. Sublingual and buccal only
    2. B. Rectal, nasogastric, and buccal routes
    3. C. Oral, rectal, and sublingual
    4. D. IV, IO, IM, SC, and intradermal
    Show answer

    Answer: D. IV, IO, IM, SC, and intradermal

    Parenteral means outside the GI tract.

15. Which is the usual order of routes from fastest to slowest onset?

    1. A. IV, IO, inhalation, IM, SC, oral
    2. B. Oral, SC, IM, inhalation, IO, IV
    3. C. IM, IV, SC, IO, inhalation, oral
    4. D. SC, IM, IV, IO, oral, inhalation
    Show answer

    Answer: A. IV, IO, inhalation, IM, SC, oral

    Inhaled medications act quickly on the lungs themselves.

16. A drug given to a patient with liver failure may:

    1. A. Be cleared faster than in a healthy patient
    2. B. Require a higher dose to reach effect
    3. C. Produce no effect at standard doses
    4. D. Accumulate and cause prolonged effects
    Show answer

    Answer: D. Accumulate and cause prolonged effects

    Dose reductions are often required. Effects may be prolonged or exaggerated.

17. A drug has 40% oral bioavailability. If 4 mg IV produces the desired effect, about what oral dose gives the same systemic exposure?

    1. A. 1.6 mg
    2. B. 10 mg
    3. C. 4 mg
    4. D. 16 mg
    Show answer

    Answer: B. 10 mg

    Only 40% of an oral dose reaches the circulation, so the oral dose must be 4 mg / 0.4 = 10 mg. Giving 4 mg orally would deliver only 1.6 mg systemically; 1.6 mg orally would deliver far less; and 16 mg would deliver 6.4 mg, well above the IV-equivalent exposure.

18. Activated charcoal reduces the toxicity of some swallowed drugs mainly by:

    1. A. Speeding the drug's liver metabolism
    2. B. Neutralizing acid in the stomach
    3. C. Adsorbing the drug in the gut
    4. D. Inducing vomiting of the tablets
    Show answer

    Answer: C. Adsorbing the drug in the gut

    Charcoal's huge surface area adsorbs (binds) many drugs in the gut so less is absorbed into the blood. It does not speed the drug's liver metabolism, it does not work by neutralizing acid in the stomach, and it does not induce vomiting of the tablets. It works best within about an hour of ingestion and is avoided when the airway is unprotected.

19. An older patient with a very dry mouth is given a sublingual nitroglycerin tablet, and it stays undissolved. The best option is to:

    1. A. Have him chew and swallow the tablet
    2. B. Place a second tablet beside the first
    3. C. Give the tablet rectally instead
    4. D. Switch to the nitroglycerin spray
    Show answer

    Answer: D. Switch to the nitroglycerin spray

    Sublingual tablets need saliva to dissolve; the spray delivers drug already in solution to the mucosa. If he chews and swallows the tablet, it passes through first-pass liver metabolism and loses most of its effect; a second tablet beside the first will not dissolve either; and giving the tablet rectally is not a field route for nitroglycerin.

20. A patient with severe bronchospasm is moving very little air. Why may his metered-dose albuterol inhaler help less than expected?

    1. A. Hypoxia inactivates albuterol
    2. B. Inhaled albuterol must pass the liver first
    3. C. The drug is absorbed too quickly to act
    4. D. Little drug reaches the small airways
    Show answer

    Answer: D. Little drug reaches the small airways

    Inhaled drugs act only where the aerosol is deposited. With poor air movement, little drug reaches the small airways, so continuous nebulization or IM epinephrine may be needed. Hypoxia does not inactivate albuterol, inhalation avoids rather than must pass the liver first, and rapid absorption at the airway is the goal, not a sign the drug is absorbed too quickly to act.

21. Compared with repeated IV push doses, a continuous infusion of the same drug produces:

    1. A. Higher peak levels after each dose
    2. B. A faster onset of the first effect than a bolus
    3. C. Steadier levels with smaller peaks and troughs
    4. D. A shorter elimination half-life
    Show answer

    Answer: C. Steadier levels with smaller peaks and troughs

    An infusion delivers drug at a constant rate, so levels rise smoothly toward steady state without the peaks and troughs of intermittent pushes. Pushes, not infusions, produce higher peak levels after each dose; a bolus, not an infusion alone, gives the faster onset of the first effect (which is why a loading dose often comes first); and the delivery method does not change the elimination half-life.

22. Which route avoids the first-pass effect?

    1. A. Enteric-coated oral capsule
    2. B. Oral liquid via nasogastric tube
    3. C. Swallowed oral tablet
    4. D. Sublingual, and partly rectal
    Show answer

    Answer: D. Sublingual, and partly rectal

    Sublingual and (to a degree) rectal routes drain into systemic venous circulation, bypassing the portal vein.

23. After an IV push, a drug reaches the brain, heart, and kidneys before muscle and fat mainly because these organs:

    1. A. Contain the most plasma protein
    2. B. Lack a lipid cell membrane
    3. C. Receive the highest blood flow
    4. D. Store drugs in their fat cells
    Show answer

    Answer: C. Receive the highest blood flow

    Distribution follows blood flow: the vessel-rich organs (brain, heart, kidneys, liver) receive most of the cardiac output and see the drug first. Plasma protein is in the blood, not concentrated in these organs; every cell has a lipid cell membrane; and these organs do not store drugs in their fat cells; fat is poorly perfused, so drug reaches it later.

24. IV lipid emulsion is used for severe bupivacaine (local anesthetic) toxicity mainly because it:

    1. A. Competitively blocks the sodium channel receptor
    2. B. Speeds renal excretion of bupivacaine
    3. C. Draws the fat-soluble drug out of tissues
    4. D. Neutralizes the drug's acidity in blood
    Show answer

    Answer: C. Draws the fat-soluble drug out of tissues

    Lipid emulsion creates a 'lipid sink' in the plasma that draws fat-soluble drug out of tissues such as the heart and brain. It does not competitively block the sodium channel receptor, it does not speed renal excretion of bupivacaine, and it does not work by neutralizing acidity in the blood. Lipid emulsion is part of the ASRA checklist for local anesthetic systemic toxicity.

25. The blood-brain barrier limits distribution of drugs that are:

    1. A. Small and highly lipophilic
    2. B. Gases such as volatile anesthetics
    3. C. Lipid-soluble and nonionized
    4. D. Water-soluble, ionized, and large
    Show answer

    Answer: D. Water-soluble, ionized, and large

    Lipid-soluble, non-ionized, small molecules cross readily.

26. Lidocaine injected into an abscess often numbs poorly. The best explanation is that the acidic tissue:

    1. A. Speeds lidocaine's metabolism in the liver
    2. B. Binds lidocaine to plasma albumin
    3. C. Keeps more lidocaine in ionized form
    4. D. Converts lidocaine into a toxic metabolite
    Show answer

    Answer: C. Keeps more lidocaine in ionized form

    Local anesthetics are weak bases. In acidic, inflamed tissue more molecules are ionized, and the ionized form crosses the nerve membrane poorly, so less drug reaches its site of action. Metabolism in the liver, binding to plasma albumin, and conversion to a toxic metabolite do not explain a local failure to numb.

27. N-acetylcysteine protects the liver after an acetaminophen overdose by:

    1. A. Blocking acetaminophen absorption in the gut
    2. B. Speeding renal excretion of acetaminophen
    3. C. Restoring the liver's glutathione
    4. D. Blocking acetaminophen at its receptor
    Show answer

    Answer: C. Restoring the liver's glutathione

    In overdose, more acetaminophen is converted to the toxic metabolite NAPQI, which glutathione detoxifies until stores run out; N-acetylcysteine works by restoring the liver's glutathione. It does not block absorption in the gut (that is activated charcoal), it does not speed renal excretion, and there is no acetaminophen receptor to block.

28. The cytochrome P450 system is important because:

    1. A. It absorbs drugs from the gut
    2. B. It metabolizes many drugs
    3. C. It excretes drugs into urine
    4. D. It binds drugs at receptors
    Show answer

    Answer: B. It metabolizes many drugs

    CYP450 induction or inhibition changes drug levels. It is also the site of many drug interactions.

29. A 'prodrug' is:

    1. A. An inert placebo given for comparison
    2. B. An inactive compound activated by metabolism
    3. C. A drug given beforehand to prevent later symptoms
    4. D. An active drug that metabolism inactivates
    Show answer

    Answer: B. An inactive compound activated by metabolism

    Example: codeine is metabolized to morphine. A drug given beforehand to prevent symptoms is prophylaxis, and an active drug inactivated by metabolism is the usual pattern, the reverse of a prodrug.

30. Hemodialysis removes a drug from the blood most effectively when the drug is:

    1. A. Highly lipid-soluble and stored in fat
    2. B. Tightly bound to plasma albumin
    3. C. Spread widely into body tissues
    4. D. Small, water-soluble, and unbound
    Show answer

    Answer: D. Small, water-soluble, and unbound

    Dialysis filters what is free in the plasma, so it works best for small, water-soluble, unbound drugs with a small volume of distribution, such as lithium, salicylate, and toxic alcohols. Drugs that are lipid-soluble and stored in fat, tightly bound to plasma albumin, or spread widely into body tissues (such as tricyclics) leave little drug in the plasma for the filter.

31. Inhaled anesthetics are primarily excreted via the:

    1. A. Liver
    2. B. Lungs
    3. C. Bile
    4. D. Kidneys
    Show answer

    Answer: B. Lungs

    Volatile agents are exhaled.

32. For a drug with first-order elimination, doubling a single dose changes its half-life by:

    1. A. Doubling the half-life
    2. B. Cutting the half-life in half
    3. C. Switching it to zero-order elimination
    4. D. Nothing; the half-life stays the same
    Show answer

    Answer: D. Nothing; the half-life stays the same

    In first-order elimination a constant fraction is removed per unit time, so the half-life does not depend on the dose. Doubling the dose only adds about one half-life to the time the level stays above a threshold. It does not double the half-life or cut it in half, and switching to zero-order elimination happens only when the eliminating enzymes saturate, as with ethanol.

33. A drug with a half-life of 4 hours will be about 94% eliminated after:

    1. A. 24 hours
    2. B. 16 hours
    3. C. 4 hours
    4. D. 8 hours
    Show answer

    Answer: B. 16 hours

    Four half-lives eliminate ~94% (50, 75, 87.5, 93.75%).

34. Steady state is generally reached after approximately:

    1. A. 4–5 half-lives
    2. B. 10 half-lives
    3. C. Immediately with IV
    4. D. One dose
    Show answer

    Answer: A. 4–5 half-lives

    Accumulation plateaus after 4–5 half-lives of regular dosing.

35. A loading dose is used to:

    1. A. Rapidly reach a therapeutic level
    2. B. Reduce side effects of later doses
    3. C. Prolong the half-life of the drug
    4. D. Slow the drug's renal excretion
    Show answer

    Answer: A. Rapidly reach a therapeutic level

    Loading doses fill the volume of distribution quickly (e.g., amiodarone bolus).

36. Renal failure affects pharmacokinetics by:

    1. A. Having no effect on drug elimination
    2. B. Speeding excretion of water-soluble drugs
    3. C. Prolonging half-life of renally cleared drugs
    4. D. Improving oral absorption of most drugs
    Show answer

    Answer: C. Prolonging half-life of renally cleared drugs

    Reduced clearance raises drug levels. This risks accumulation.

37. Hepatic disease most directly impairs:

    1. A. Metabolism
    2. B. Distribution to bone
    3. C. Absorption
    4. D. Renal filtration
    Show answer

    Answer: A. Metabolism

    Liver dysfunction reduces biotransformation capacity.

38. Onset of action is:

    1. A. Length of the drug's effect
    2. B. Time to first observable effect
    3. C. Time for the level to halve
    4. D. Time to the peak blood concentration
    Show answer

    Answer: B. Time to first observable effect

    Onset depends on route and absorption.

39. Duration of action is:

    1. A. Time for the level to drop by half
    2. B. Time from dose to first effect
    3. C. Length of time the effect lasts
    4. D. Time until excretion is complete
    Show answer

    Answer: C. Length of time the effect lasts

    Duration guides redosing intervals.

40. Which factor slows absorption of an IM injection?

    1. A. Good perfusion of the muscle
    2. B. Warm skin over the injection site
    3. C. Exercise of the injected limb
    4. D. Poor peripheral perfusion
    Show answer

    Answer: D. Poor peripheral perfusion

    Reduced blood flow to the site delays uptake — important in shock. Causes include shock and hypothermia.

41. Passive diffusion moves drugs:

    1. A. Against a gradient using cellular energy
    2. B. Down a gradient without using energy
    3. C. Only through water-filled membrane pores
    4. D. Only with the help of carrier proteins
    Show answer

    Answer: B. Down a gradient without using energy

    Most drug absorption is passive diffusion.

42. Active transport differs from passive diffusion in that it:

    1. A. Requires no energy and no carrier
    2. B. Uses energy and carriers to move against a gradient
    3. C. Occurs only in the kidney's renal tubules
    4. D. Is always slower than passive diffusion
    Show answer

    Answer: B. Uses energy and carriers to move against a gradient

    Active transport uses ATP and carrier proteins. It requires carrier proteins.

43. Ion trapping refers to:

    1. A. An ionized drug unable to cross back
    2. B. Retention of electrolytes by the kidney
    3. C. Loss of ions during rapid IV infusion
    4. D. Binding of a drug to ions at its receptor
    Show answer

    Answer: A. An ionized drug unable to cross back

    Weak acids/bases ionize depending on pH; this is used in some overdose treatments (urinary alkalinization). The drug ionizes on one side of a membrane and cannot cross back.

44. Volume of distribution (Vd) describes:

    1. A. The volume of plasma cleared per hour
    2. B. The total dose divided by the half-life
    3. C. The apparent space the drug occupies
    4. D. The patient's circulating blood volume
    Show answer

    Answer: C. The apparent space the drug occupies

    A large Vd indicates extensive tissue distribution. The volume of plasma cleared per unit time is clearance, a different measure.

45. Which patient would be expected to have altered drug distribution?

    1. A. A healthy adult of normal weight
    2. B. A well-conditioned endurance athlete
    3. C. A malnourished patient with low albumin
    4. D. A child with normal weight and normal hydration
    Show answer

    Answer: C. A malnourished patient with low albumin

    Low albumin increases the free fraction of protein-bound drugs. Liver disease also lowers albumin.

46. Enterohepatic recirculation can:

    1. A. Shorten a drug's duration of action
    2. B. Occur only with intravenous drugs
    3. C. Prevent the drug's absorption from the intestine
    4. D. Prolong drug action by reabsorbing drug from bile
    Show answer

    Answer: D. Prolong drug action by reabsorbing drug from bile

    Some drugs cycle between liver, bile, and intestine.

47. Transdermal absorption is affected by:

    1. A. Gastric emptying and food intake
    2. B. Skin thickness, heat, and perfusion
    3. C. The size of the patch and nothing else
    4. D. First-pass metabolism in the liver
    Show answer

    Answer: B. Skin thickness, heat, and perfusion

    Heat and perfusion increase absorption — a concern with fentanyl patches. Gastric emptying affects oral drugs, and transdermal drugs enter the systemic circulation directly, so first-pass metabolism does not limit them.

48. Rectal drug administration is useful in EMS because:

    1. A. It has the fastest onset of any route
    2. B. It can be used in seizing or vomiting patients
    3. C. It gives precise, predictable absorption
    4. D. It is painless and preferred by patients
    Show answer

    Answer: B. It can be used in seizing or vomiting patients

    Rectal diazepam is an example for pediatric seizures. It also partially bypasses first-pass metabolism.

49. Which factor most affects oral absorption?

    1. A. The drug's degree of binding to plasma proteins
    2. B. Gastric emptying and food in the stomach
    3. C. The patient's renal function
    4. D. The time of day the dose is taken
    Show answer

    Answer: B. Gastric emptying and food in the stomach

    GI physiology determines oral drug uptake rate. Gut motility also matters. Protein binding affects distribution after absorption, and renal function affects excretion rather than uptake from the gut.

50. A patient receives 100 mg of a drug with a half-life of 2 hours. About how much remains after 6 hours?

    1. A. 50 mg
    2. B. 12.5 mg
    3. C. 25 mg
    4. D. 6.25 mg
    Show answer

    Answer: B. 12.5 mg

    Six hours is three half-lives: 100 to 50 to 25 to 12.5 mg.

51. IV morphine reaches its peak effect about 10 to 20 minutes after each dose. A paramedic who gives 4 mg every 3 minutes for severe pain risks:

    1. A. Rapid tolerance to morphine's effects
    2. B. Stacking doses before each one peaks
    3. C. Needing a lower total dose overall
    4. D. Faster renal excretion of the drug
    Show answer

    Answer: B. Stacking doses before each one peaks

    Redosing before the previous dose has peaked stacks the effects, so sedation and respiratory depression appear after the patient seemed to need more; wait to see each dose's peak before repeating. Rapid tolerance does not develop over minutes, stacking raises rather than lowers the total dose overall, and frequent dosing does not cause faster renal excretion.

52. A drug has a half-life of 30 minutes. Roughly how long until it is considered essentially eliminated?

    1. A. 30 minutes
    2. B. 5 hours
    3. C. 2.5 hours
    4. D. 1 hour
    Show answer

    Answer: C. 2.5 hours

    About 5 half-lives (5 x 30 minutes) are needed to eliminate roughly 97% of a drug.

53. Adenosine has a half-life of less than 10 seconds. This is why it must be:

    1. A. Mixed into a large bag of fluid
    2. B. Infused slowly over 10 minutes by pump
    3. C. Given by rapid IV push with a flush
    4. D. Given IM for a sustained effect
    Show answer

    Answer: C. Given by rapid IV push with a flush

    Adenosine is metabolized so rapidly by red cells and endothelium that it must reach the heart as a fast bolus. Use a site close to the heart and flush immediately.

54. After naloxone reverses a methadone overdose, the patient becomes apneic again 45 minutes later. The best explanation is:

    1. A. Naloxone increases methadone absorption
    2. B. Naloxone caused a delayed allergic reaction
    3. C. Methadone is not a true opioid agonist
    4. D. Naloxone wears off before methadone does
    Show answer

    Answer: D. Naloxone wears off before methadone does

    Long-acting opioids can outlast naloxone, so renarcotization requires monitoring and possible redosing.

55. A patient swallows a nitroglycerin tablet instead of letting it dissolve under the tongue. The weaker effect is mainly due to:

    1. A. First-pass metabolism in the liver
    2. B. Down-regulation of nitrate receptors
    3. C. Increased protein binding in the stomach
    4. D. Faster renal excretion of nitroglycerin
    Show answer

    Answer: A. First-pass metabolism in the liver

    Sublingual absorption enters the systemic circulation directly; swallowed nitroglycerin is largely inactivated by the liver first.

56. The intraosseous (IO) route has pharmacokinetics most similar to the:

    1. A. Transdermal route
    2. B. Subcutaneous route
    3. C. Intravenous route
    4. D. Oral route
    Show answer

    Answer: C. Intravenous route

    The marrow's noncollapsible venous sinusoids drain into the central circulation, so IO onset and dosing match IV.

57. Endotracheal drug administration is no longer preferred mainly because:

    1. A. It causes immediate first-pass metabolism
    2. B. It requires a central line to be in place
    3. C. It works only with water-soluble drugs
    4. D. Absorption is erratic and levels are lower
    Show answer

    Answer: D. Absorption is erratic and levels are lower

    Current resuscitation guidelines favor IV or IO because endotracheal drug levels are erratic.

58. Intranasal medications are absorbed best when:

    1. A. Atomized at about 1 mL per nostril
    2. B. Given as drops with the head tilted back
    3. C. Sprayed as about 3 mL per nostril
    4. D. A large volume is squirted into one nostril
    Show answer

    Answer: A. Atomized at about 1 mL per nostril

    Small, atomized volumes spread over the vascular mucosa; excess volume runs off or is swallowed. Drops with the head back tend to run into the throat and be swallowed, and volumes well above 1 mL per nostril overflow the mucosa.

59. IM epinephrine for anaphylaxis is given into the anterolateral thigh rather than subcutaneously or into the deltoid because:

    1. A. The thigh route avoids first-pass metabolism
    2. B. Subcutaneous fat absorbs it more quickly
    3. C. The deltoid inactivates catecholamines
    4. D. The thigh muscle absorbs it faster
    Show answer

    Answer: D. The thigh muscle absorbs it faster

    Peak epinephrine levels are reached faster after IM injection into the vastus lateralis than after subcutaneous or deltoid injection. Every injected route avoids first-pass metabolism, so that is not the difference; subcutaneous fat absorbs it more slowly, not more quickly; and the deltoid does not inactivate catecholamines.

60. Compared with intramuscular injection, subcutaneous injection generally produces:

    1. A. Faster absorption because fat is lipid-rich
    2. B. Identical absorption rates in all patients
    3. C. Slower absorption due to lower blood flow
    4. D. Absorption only after first-pass metabolism
    Show answer

    Answer: C. Slower absorption due to lower blood flow

    Muscle is more vascular than subcutaneous tissue, so IM absorption is usually faster.

61. Oral liquid medications usually act faster than tablets because:

    1. A. They are always more concentrated than tablets
    2. B. They do not need to dissolve first
    3. C. They are absorbed directly in the mouth
    4. D. They avoid hepatic first-pass metabolism
    Show answer

    Answer: B. They do not need to dissolve first

    Dissolution is often the rate-limiting step for solid dosage forms. Tablets must disintegrate and dissolve before absorption.

62. Enteric-coated tablets are designed to:

    1. A. Release drug in the mouth for fast onset
    2. B. Dissolve rapidly under the tongue
    3. C. Bypass hepatic metabolism entirely
    4. D. Resist stomach acid and dissolve in the intestine
    Show answer

    Answer: D. Resist stomach acid and dissolve in the intestine

    Enteric coating protects the stomach from the drug or the drug from stomach acid. They then dissolve in the small intestine.

63. A weak acid such as aspirin is mostly in its nonionized (absorbable) form in:

    1. A. An alkaline environment such as the intestine
    2. B. The acidic environment of the stomach
    3. C. The bloodstream, regardless of pH
    4. D. Any pH environment to the same degree
    Show answer

    Answer: B. The acidic environment of the stomach

    Weak acids stay nonionized in acid, which favors diffusion across lipid membranes.

64. Alkalinizing the urine with sodium bicarbonate in salicylate poisoning increases elimination because:

    1. A. It increases protein binding of salicylate
    2. B. Bicarbonate binds salicylate in the stomach
    3. C. It increases salicylate metabolism in the liver
    4. D. Ionized salicylate is trapped in the urine
    Show answer

    Answer: D. Ionized salicylate is trapped in the urine

    This applies ion trapping: a weak acid ionizes in alkaline urine and is excreted rather than reabsorbed.

65. Glycopyrrolate causes fewer CNS effects than atropine because it:

    1. A. Is more lipid-soluble than atropine
    2. B. Has a much shorter half-life than atropine
    3. C. Acts only at nicotinic receptor sites
    4. D. Is charged and stays out of the brain
    Show answer

    Answer: D. Is charged and stays out of the brain

    Charged quaternary amines stay out of the CNS, so central anticholinergic effects are minimal. Glycopyrrolate is a highly ionized quaternary compound that does not readily cross the blood-brain barrier.

66. A single IV dose of a highly lipid-soluble induction agent wears off within minutes mainly because of:

    1. A. Redistribution from brain to muscle and fat
    2. B. Binding to albumin within brain tissue
    3. C. Immediate hepatic metabolism of the drug
    4. D. Rapid excretion of unchanged drug by the kidneys
    Show answer

    Answer: A. Redistribution from brain to muscle and fat

    Lipid-soluble drugs reach the brain quickly, then redistribute to other tissues, ending the clinical effect before metabolism is complete.

67. When two highly protein-bound drugs compete for albumin binding sites, the usual result is:

    1. A. No change in the effect of either drug
    2. B. Complete inactivation of both drugs by binding
    3. C. More free drug of the displaced agent
    4. D. Less free drug of both agents in plasma
    Show answer

    Answer: C. More free drug of the displaced agent

    Only unbound drug is active, so displacement from albumin can push free levels into the toxic range. The result is a stronger effect of the displaced drug.

68. A malnourished patient with low albumin takes phenytoin. Compared with a healthy patient at the same total level, this patient has:

    1. A. Faster absorption but no toxicity risk
    2. B. A higher free fraction and greater toxicity risk
    3. C. No meaningful difference in drug effect
    4. D. Lower free drug and a weaker effect
    Show answer

    Answer: B. A higher free fraction and greater toxicity risk

    Phenytoin is highly albumin-bound; low albumin raises the active free fraction.

69. At typical intoxicating levels, ethanol is eliminated by zero-order kinetics, meaning:

    1. A. Elimination stops at very high concentrations
    2. B. A constant amount is eliminated per hour
    3. C. A constant fraction is eliminated per hour
    4. D. Half-life stays fixed at all concentrations
    Show answer

    Answer: B. A constant amount is eliminated per hour

    Alcohol dehydrogenase is saturated, so the body clears a fixed amount per hour. The amount cleared does not depend on concentration.

70. Most drugs follow first-order elimination, which means:

    1. A. Elimination rate depends only on the dose size
    2. B. The drug is never completely eliminated from the body
    3. C. A constant fraction is eliminated per unit time
    4. D. A constant amount is eliminated per unit time
    Show answer

    Answer: C. A constant fraction is eliminated per unit time

    With first-order kinetics, the half-life stays constant and the amount removed falls as concentration falls.

71. Clearance is best defined as:

    1. A. Volume of plasma cleared of drug per unit time
    2. B. The time to reach peak concentration
    3. C. The fraction of drug bound to protein
    4. D. The dose needed for a therapeutic effect
    Show answer

    Answer: A. Volume of plasma cleared of drug per unit time

    Clearance, usually expressed in mL/min, together with volume of distribution determines half-life.

72. Glomerular filtration removes:

    1. A. All drug regardless of binding
    2. B. Only the unbound (free) drug
    3. C. Only lipid-soluble drug molecules
    4. D. Only the drug bound to albumin
    Show answer

    Answer: B. Only the unbound (free) drug

    Albumin-bound drug is too large to pass the glomerulus, so only free drug is filtered.

73. Phase II (conjugation) reactions such as glucuronidation generally make a drug:

    1. A. Better able to cross the blood-brain barrier
    2. B. More water-soluble and easier to excrete
    3. C. More tightly bound to plasma proteins
    4. D. More lipid-soluble and longer-acting
    Show answer

    Answer: B. More water-soluble and easier to excrete

    Conjugation adds polar groups that let the kidneys excrete the drug.

74. Chronic use of an enzyme inducer such as carbamazepine or rifampin will usually:

    1. A. Increase protein binding of most other drugs
    2. B. Slow the metabolism of other drugs
    3. C. Block renal excretion of other drugs
    4. D. Speed metabolism and lower drug levels
    Show answer

    Answer: D. Speed metabolism and lower drug levels

    Inducers increase cytochrome P450 activity, which can make co-administered drugs less effective.

75. The therapeutic range of a drug lies between:

    1. A. The minimum effective and toxic levels
    2. B. Zero and the minimum effective level
    3. C. The ED50 and the drug's onset time
    4. D. The peak and trough concentrations after each dose
    Show answer

    Answer: A. The minimum effective and toxic levels

    Below the MEC there is no effect; above the toxic concentration adverse effects predominate.

76. Amiodarone has an elimination half-life measured in weeks. A practical consequence is that:

    1. A. It is eliminated before it can take effect
    2. B. It must be redosed every few minutes
    3. C. It never reaches a steady-state concentration
    4. D. Its effects persist long after stopping
    Show answer

    Answer: D. Its effects persist long after stopping

    Extensive tissue storage gives amiodarone a very long half-life, so interactions outlast discontinuation. Drug interactions also persist.

77. A febrile patient with a fentanyl patch develops sedation and slow respirations. The most likely reason is:

    1. A. Heat inactivated the fentanyl in the patch
    2. B. Fever increased hepatic metabolism of fentanyl
    3. C. Heat increased skin blood flow and patch absorption
    4. D. Fever lowered fentanyl protein binding to zero
    Show answer

    Answer: C. Heat increased skin blood flow and patch absorption

    Fever, heating pads, and hot tubs speed transdermal absorption and can cause opioid toxicity.

78. In a patient with heart failure, lidocaine may accumulate to toxic levels because:

    1. A. Lidocaine is excreted unchanged by the lungs
    2. B. Heart failure raises protein binding to 100%
    3. C. Heart failure increases gut absorption of lidocaine
    4. D. Low liver blood flow reduces its clearance
    Show answer

    Answer: D. Low liver blood flow reduces its clearance

    Lidocaine clearance depends on liver blood flow, which falls with low cardiac output. Lidocaine is a highly liver-extracted drug.

79. A main pharmacokinetic advantage of nebulized albuterol is that it:

    1. A. Delivers drug directly to the airways
    2. B. Forms a long-acting depot in muscle
    3. C. Requires first-pass metabolism to activate
    4. D. Bypasses the airways and acts systemically
    Show answer

    Answer: A. Delivers drug directly to the airways

    Inhalation delivers the drug directly to its site of action in the airways, so lower doses work, onset is rapid, and systemic exposure and side effects are limited. A muscle depot describes IM depot drugs, albuterol is active as given rather than a prodrug needing first-pass activation, and the point of nebulizing is to act in the airways rather than bypass them.

80. During cardiac arrest, a drug given through a peripheral IV should be followed by a fluid flush and elevation of the extremity to:

    1. A. Speed drug delivery to the heart
    2. B. Allow first-pass metabolism to occur
    3. C. Increase protein binding of the drug
    4. D. Slow absorption and prevent toxicity
    Show answer

    Answer: A. Speed drug delivery to the heart

    Low flow during CPR delays peripheral drug delivery; a 20-mL flush and limb elevation help. The goal is faster delivery to the central circulation.