Which of the following statements about drug metabolism in pharmacokinetics is correct?
Drugs with strong first-pass metabolism are best administered via an enteral route
Metabolism alters medications so that they can be excreted from the body
The first-pass effect increases the bioavailability of orally administered drugs
Metabolism primarily occurs in the kidneys
The Correct Answer is B
A. Drugs with strong first-pass metabolism are best administered via an enteral route: Drugs that undergo extensive first-pass metabolism are often less effective when given enterally, as much of the drug is inactivated by the liver before reaching systemic circulation. Non-enteral routes (e.g., sublingual, IV) are preferred to bypass the liver initially.
B. Metabolism alters medications so that they can be excreted from the body: The liver uses enzymatic processes to convert drugs into more water-soluble forms, facilitating their elimination through the kidneys or bile. This process can either activate, inactivate, or detoxify substances depending on the drug.
C. The first-pass effect increases the bioavailability of orally administered drugs: The first-pass effect reduces, not increases, the bioavailability of orally administered drugs. It refers to the initial metabolism in the liver that significantly reduces the active concentration of a drug before it reaches systemic circulation.
D. Metabolism primarily occurs in the kidneys: While the kidneys are essential for drug excretion, metabolism primarily occurs in the liver. Hepatic enzymes, especially those of the cytochrome P-450 system, play the central role in drug biotransformation.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A. "This will make it easier to cough up mucus.": Guaifenesin is an expectorant that works by thinning respiratory tract secretions, making it easier to mobilize and expel mucus through coughing. It does not suppress the cough reflex but facilitates a more productive cough.
B. "I should take this medication with other cough suppressants for best results.": Combining an expectorant like guaifenesin with a cough suppressant can be counterproductive. Suppressing the cough may prevent the effective clearing of loosened mucus, potentially worsening congestion.
C. "This medication will eliminate my cough within 24 hours.": Guaifenesin does not provide immediate relief and does not "eliminate" coughs. Its effectiveness depends on consistent use, and improvement may take a few days depending on the underlying cause of the cough.
D. "I should avoid drinking fluids while taking this medication.": Adequate fluid intake is essential while taking guaifenesin, as it enhances the medication's mucolytic effects. Dehydration can reduce its effectiveness and make secretions thicker and harder to clear.
Correct Answer is B
Explanation
A. Second-generation antihistamines have shorter half-lives and require more frequent dosing compared to first-generation antihistamines: Second-generation antihistamines typically have longer half-lives, allowing once-daily dosing. They are designed for sustained action with improved compliance and fewer side effects.
B. First-generation antihistamines block both histamine and muscarinic receptors, while second-generation antihistamines primarily block histamine receptors: First-generation agents, such as diphenhydramine, cross the blood-brain barrier and exert anticholinergic effects by blocking muscarinic receptors. Second-generation antihistamines are more selective for peripheral H1 receptors, resulting in fewer CNS and anticholinergic side effects.
C. First-generation antihistamines are less likely to cause sedation compared to second-generation antihistamines: First-generation antihistamines are more likely to cause sedation because they easily penetrate the blood-brain barrier and affect central H1 receptors, unlike second-generation agents.
D. Second-generation antihistamines cross the blood-brain barrier, causing significant central nervous system effects: These medications are designed not to cross the blood-brain barrier significantly, which is why they are much less sedating and have minimal CNS effects compared to first-generation antihistamines.
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