Help solving this problem - PK

[shahhar]

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A patient is receiving vancomycin 1,250 mg IV Q12H. The following drug levels are available and orders to hold vancomycin are received after the first level comes back.

1/8: 41.45 mcg/mL at 1800
1/8: 35.6 mcg/mL at 2230
1/9: 22.55 mcg/mL at 1200
1/9: 17.8 mcg/mL at 1900
1/9: 16.36 mcg/mL at 2130
What is the patient's vancomycin half-life in hours?

 

[blawndesrntdum]

No math needed! The vancomycin level halved from the second (35.6 mcg/mL) to the fourth (17.8 mcg/mL) levels, taken 20.5 hours apart. The half-life is 20.5 hours.

 

[shahhar]

Thanks