**Question:** Complication of cyclosporine therapy is:

A. Nephrotoxicity
B. Hepatotoxicity
C. Neurotoxicity
D. Hyperlipidemia

**Core Concept:** Cyclosporine is an immunosuppressive drug used to prevent organ transplant rejection. It works by inhibiting T-cell activation and proliferation. However, it may cause various side effects due to its effects on various organs and systems.

**Why the Correct Answer is Right:** Nephrotoxicity is the correct answer because cyclosporine can cause dose-dependent renal toxicity. Cyclosporine competes with magnesium ions for binding sites on the renal tubule cell membrane, leading to magnesium wasting and nephrotoxicity. Cyclosporine also inhibits sodium reabsorption, causing increased free water reabsorption and urine concentration.

**Why Each Wrong Option is Incorrect:**

1. Hepatotoxicity (B): Although cyclosporine can cause liver dysfunction, it is not as predominant a side effect as nephrotoxicity. Cyclosporine's hepatotoxicity is typically dose-dependent and reversible upon dose reduction.
2. Neurotoxicity (C): Though cyclosporine can cause neurotoxicity, it is less common than nephrotoxicity. Neurotoxicity manifests as headache, dizziness, and seizures.
3. Hyperlipidemia (D): While cyclosporine can lead to hyperlipidemia, it is not the primary complication of cyclosporine therapy. Hyperlipidemia is often seen in combination with other medications used in organ transplant patients, such as steroids and azathioprine.

**Clinical Pearl:** Regular monitoring of renal function tests is essential when prescribing cyclosporine, as early detection of nephrotoxicity can prevent further renal damage.

**Correct Answer:** Nephrotoxicity (A)