The primary excretory organ for the local anaesthetic and its metabolites is:
**Core Concept**
The primary excretory organ for local anaesthetics and their metabolites is responsible for eliminating these substances from the body, ensuring their safe metabolism and preventing potential toxicity. This process involves the kidneys and liver, where the drugs are either excreted in the urine or metabolized into inactive compounds.
**Why the Correct Answer is Right**
The kidneys, specifically the renal cortex, play a crucial role in the excretion of local anaesthetics and their metabolites. This process occurs through glomerular filtration, where the substances are filtered from the blood into the renal tubules, and then excreted in the urine. The liver also metabolizes local anaesthetics, but the kidneys are primarily responsible for their excretion. The renal excretion of local anaesthetics is influenced by factors such as kidney function, urine flow rate, and the presence of other drugs that may affect renal function.
**Why Each Wrong Option is Incorrect**
**Option A:** The liver is primarily responsible for metabolizing local anaesthetics, but it is not the primary excretory organ.
**Option B:** The skin is not a significant route for the excretion of local anaesthetics or their metabolites.
**Option C:** The lungs are not directly involved in the excretion of local anaesthetics or their metabolites.
**Clinical Pearl / High-Yield Fact**
Local anaesthetics can cause nephrotoxicity, particularly if they are not metabolized or excreted properly. This can lead to acute kidney injury or chronic kidney disease.
**Correct Answer: C. Kidneys**