Why does lidocaine, administered orally, have limited use as a systemic analgesic, despite its demonstrated analgesic effectiveness when administered intravenously?

💡 Explanation

Lidocaine's oral bioavailability is low because a significant portion of the drug is metabolized by the liver during its first pass through the hepatic portal system. Therefore, intravenous administration bypasses this first-pass metabolism, rather than direct absorption or renal elimination, leading to higher systemic drug concentrations.

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