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When reviewing the mechanism of action of a specific drug, the nurse reads that the drug works by selective enzyme interaction. Which of these processes describes selective enzyme interaction?
- A. The drug alters cell membrane permeability.
- B. The drug's effectiveness within the cell walls of the target tissue is enhanced.
- C. The drug is attracted to a receptor on the cell wall, preventing an enzyme from binding to that receptor.
- D. The drug binds to an enzyme molecule and inhibits or enhances the enzyme's action with the normal target cell.
Correct Answer: D
Rationale: With selective enzyme interaction, the drug attracts the enzymes to bind with the drug instead of allowing the enzymes to bind with their normal target cells. As a result, the target cells are protected from the action of the enzymes. This results in a drug effect. The actions described in the other options do not occur with selective enzyme interactions.
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Which drugs would be affected by the first-pass effect when administered?
- A. Morphine given by IV push injection
- B. Sublingual nitroglycerin tablet
- C. Diphenhydramine elixir
- D. Levotthroxine (Synthroid) tablet
- E. Transdermal nicotine patches
- F. Esomeparzole capsule
- G. Penicillin given by IV piggyback infusion
Correct Answer: C,D,F
Rationale: Orally administered drugs (elixirs, tablets, and capsules) undergo the first-pass effect, because they are metabolized in the liver after being absorbed into the portal circulation from the small intestine. IV medications (IV push and IV piggyback) enter the bloodstream directly and do not go directly to the liver. Sublingual tablets and transdermal patches also enter the bloodstream without going directly to the liver, thus avoiding the first-pass effect.
When administering drugs, the nurse remembers that the duration of action of a drug is defined as which of these?
- A. The time it takes for a drug to elicit a therapeutic response
- B. The amount of time needed to remove a drug from circulation
- C. The time it takes for a drug to achieve its maximum therapeutic response
- D. The time period at which a drug's concentration is sufficient to cause a therapeutic response
Correct Answer: D
Rationale: Duration of action is the time during which drug's concentration is sufficient to elicit a therapeutic response. The other options do not define duration of action. A drug's onset of action is the time it takes for the drug to elicit a therapeutic response. A drug's peak effect is the time it takes for the drug to reach its maximum therapeutic response. Elimination is the length of time it takes to remove a drug from circulation.
When administering a new medication to a patient, the nurse reads that it is highly protein bound. Assuming that the patient's albumin levels are normal, the nurse would expect which result, as compared to a medication, that is not highly protein bound?
- A. Renal excretion will be faster.
- B. The drug will be metabolized quickly.
- C. The duration of action of the medication will be shorter.
- D. The duration of action of the medication will be longer.
Correct Answer: D
Rationale: Drugs that are bound to plasma proteins are characterized by longer duration of action. Protein binding does not make renal excretion faster, does not speed up drug metabolism, and does not cause the duration of action to be shorter.
A patient who has advanced cancer is receiving opioid medications around the clock to keep him comfortable as he nears the end of his life. Which term best describes this type of therapy?
- A. Pallative therapy
- B. Maintenance therapy
- C. Empirric therapy
- D. Supplmental therapy
Correct Answer: A
Rationale: The goal of palliative therapy is to make the patient as comfortable as possible. It is typically used in the end stages of illnesses when all attempts at curative therapy have failed. Maintenance therapy is used for the treatment of chronic illnesses such as hypertension. Empirric therapy is based on clinical probabilities and involves drug administration when a certain pathologic condition has an uncertain but high likelihood of occurrence based on the patient's initial presenting symptoms. Supplemental therapy (or replacement therapy) supplies the body with a substance needed to maintain normal function.
The nurse will be injecting a drug into the superficial skin layers immediately underneath the epidermal layer of skin. Which route does this describe?
- A. Intradermal
- B. Subcutaneous
- C. Intramuscular
- D. Transdermal
Correct Answer: A
Rationale: Injections under the more superficial skin layers immediately underneath the epidermal layer of skin and into the dermal layer are known as intradermal injections. Injections into the fatty subcutaneous tissue under the dermal layer of skin are referred to as subcutaneous injections. Injections into the muscle beneath the subcutaneous fatty tissue are referred to as intramuscular injections. Transdermal drugs are applied to the skin via an adhesive patch.