6. The initial dosage of a drug is 5 mg/kg of body weight. If a patient weighs 185 lb, what is the total initial dose, in mg?
Answer: C
The total initial dose for a patient weighing 185 lb is 420 mg.
To calculate the total initial dose, we first convert the patient's weight from pounds to kilograms. Since 1 pound is approximately 0.453592 kilograms, a patient weighing 185 lb is approximately 83.91 kg. Multiplying this weight by the dosage of 5 mg/kg results in a total dose of about 420 mg.
A) 81.4
This option is incorrect. A dose of 81.4 mg would not be sufficient for a patient weighing 185 lb, as the calculation based on the weight indicates a higher required dosage.
B) 185
This option is also incorrect. A total dose of 185 mg does not align with the calculated requirement based on the patient's weight and the prescribed dosage of 5 mg/kg.
C) 420
This option is correct. The calculation shows that a patient weighing 185 lb, which converts to approximately 83.91 kg, requires a total initial dose of 420 mg when applying the dosage of 5 mg/kg.
D) 925
This option is incorrect. A total dose of 925 mg exceeds the calculated requirement for a patient of this weight, making it an inappropriate choice based on the given dosage guidelines.
Conclusion
The correct answer is 420 mg, as derived from converting the patient's weight from pounds to kilograms and applying the dosage of 5 mg/kg. All other options fail to meet the necessary dosage requirement based on the patient's actual weight, confirming that 420 mg is the only valid choice.