MEDizzy - Azithromycin, an antibiotic, has an apparent volume of

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General pharmacology

Azithromycin, an antibiotic, has an apparent volume of distribution (Vd) of approximately 30 L/kg. The best interpretation of this information is that azithromycin is which of the following?

ExplanationFor a 70-kg individual, total body water is about 40 L (0.6 L/kg); interstitial plus plasma water occupies about 12 L (0.17 L/kg). Azithromycin, with a Vd of 30 L/kg, would be distributed in an apparent volume of about 2100 L in a typical 70-kg person. Use simple logic to answer this question, but look at the answer to Question 17, if you wish. Even if you don’t remember what total body water is (about 40 L or 0.6 L/kg) or the approximate value for interstitial plus plasma water (about 12 L or 0.17 L/kg), do the quick math. If you take the stated 30 L/kg and compute the total (and very hypothetical) apparent volume for a 70-kg individual, you would arrive at 2100 L. That number not only reflects distribution into a hypothetical volume far in excess of vascular and interstitial volumes but is also far beyond what could be physically real. After all, 2100 L of water equals 2100 kg; you won’t find human beings weighing that much! Without more information, you cannot make definitive conclusions about the other properties listed as answer choices.