A nurse is administering a medication with a half-life of 6 hours. If the initial dose is 800 mg, how much of the medication will remain in the patient's system after 18 hours?
300 mg
400 mg
200 mg
100 mg
The Correct Answer is D
A. 300mg is incorrect.
B. 400mg is incorrect
C. 200mg is incorrect
D. The half-life of a drug is the time it takes for the plasma concentration of a drug to decrease by 50%. If the half-life is 6 hours, the amount of drug in the body will halve every 6 hours.
- Initial dose: 800 mg
- After 6 hours (1st half-life): 800 mg ÷ 2 = 400 mg
- After 12 hours (2nd half-life): 400 mg ÷ 2 = 200 mg
- After 18 hours (3rd half-life): 200 mg ÷ 2 = 100 mg
After 18 hours (three half-lives), 100 mg of the medication will remain in the patient's system.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is ["15.16"]
Explanation
Given time = 3:16 pm
For times between 1:00 pm and 11:59 pm, add 12 to the hour to convert to military time.
Hour in traditional time = 3
Military time hour = 3 + 12 = 15
The minutes remain the same.
Minutes = 16
Military time = 15:16
Correct Answer is A
Explanation
A. Cushing's syndrome: Prolonged use of corticosteroids can lead to iatrogenic Cushing's syndrome. Common features include weight gain (especially central), mood changes such as anxiety or irritability, insomnia, and physical changes like hirsutism (increased facial hair), moon face, and truncal obesity due to chronic hypercortisolism.
B. Adrenal insufficiency: This condition typically results from abrupt withdrawal of corticosteroids, leading to fatigue, hypotension, and electrolyte imbalances. It does not cause the excess cortisol-related symptoms described in this patient’s presentation.
C. Diabetes mellitus: While corticosteroids can raise blood glucose levels and increase the risk for diabetes, the described symptoms—particularly the weight distribution and hirsutism—are more indicative of Cushing’s syndrome than diabetes.
D. Dystonia: Dystonia involves involuntary muscle contractions causing repetitive movements or abnormal postures. It is not associated with the metabolic and hormonal effects caused by long-term corticosteroid use.
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