A patient is receiving intravenous vancomycin. The physician wants to know the medication's effectiveness, so a trough drug level is ordered. The nurse should obtain the patient's blood sample:

Immediately before the next drug administration.

Explanation

•Vancomycin levels are monitored to ensure the dose ordered is correct to maintain a therapeutic dose.

•A trough is measured during the drug's lowest level, immediately before the next administered dose.

Incorrect options:

•Obtaining a blood sample too early will not represent a trough, because it will not be as low as it would be just before the next dose.

•Obtaining a blood sample after administering the medication would measure a higher level, not a trough.

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