Why does a hydrophilic drug, like gentamicin, typically exhibit a smaller volume of distribution compared to a lipophilic drug, such as diazepam?

💡 Explanation

Gentamicin, being hydrophilic, primarily distributes into the blood and interstitial fluid, which are aqueous compartments. This limits its distribution compared to lipophilic drugs. Because the volume of distribution is smaller for gentamicin, its concentration in those compartments will be higher, therefore it does not distribute into adipose tissue like diazepam, rather than undergoing significant first-pass metabolism.

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