**Core Concept**
Hyperkalemia is a condition characterized by elevated serum potassium levels, which can be life-threatening if left untreated. Managing hyperkalemia requires careful pharmacological intervention to stabilize cardiac membranes, promote potassium excretion, or reduce potassium levels.

**Why the Correct Answer is Right**
Magnesium sulphate is not used for treating hyperkalemia. Instead, it can exacerbate the condition by increasing potassium levels. Magnesium sulphate can also interfere with digitalis toxicity treatment, which is often used in conjunction with other treatments for hyperkalemia. In contrast, the other options are used to manage hyperkalemia by stabilizing cardiac membranes (Calcium gluconate), promoting potassium excretion (Sodium bicarbonate), or reducing potassium levels (Salbutamol through beta-2 agonism).

**Why Each Wrong Option is Incorrect**
**Option A:** Salbutamol is a beta-2 agonist that helps reduce potassium levels by driving potassium into cells. This makes it a useful treatment for hyperkalemia.
**Option B:** Calcium gluconate is used to stabilize cardiac membranes and counteract the cardiac effects of hyperkalemia.
**Option C:** Sodium bicarbonate is used to promote potassium excretion by increasing the excretion of potassium in the urine.

**Clinical Pearl / High-Yield Fact**
When managing hyperkalemia, it's essential to remember that the treatment goal is to reduce the serum potassium level to prevent cardiac complications. Beta-2 agonists like salbutamol can be particularly effective in this regard.

**Correct Answer Line**
✓ Correct Answer: D. Magnesium sulphate