## **Core Concept**
Thiopentone, also known as thiopental, is a barbiturate that has been widely used for inducing anesthesia. Its physical state and formulation are crucial for its administration. The question pertains to the physical characteristics of thiopentone.

## **Why the Correct Answer is Right**
Thiopentone is supplied as a yellow crystalline powder that is highly soluble in water, forming a stable solution. When dissolved in a buffered solution (usually 0.9% sodium chloride or 5% dextrose), it forms a **hypnotic** solution that can be used intravenously for rapid induction of anesthesia. The solution is **alkaline**, with a pH of around 10-11, which helps to keep the thiopentone in its **unionized, lipid-soluble form** during administration. This facilitates its rapid passage across the blood-brain barrier.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Incorrect because thiopentone is not supplied as a suspension; it's a powder for dissolution.
- **Option B:** Incorrect because thiopentone solution is not acidic; it's alkaline.
- **Option C:** Incorrect because thiopentone is not oily; it's water-soluble.

## **Clinical Pearl / High-Yield Fact**
Thiopentone's rapid onset of action is due to its high lipid solubility, allowing it to quickly cross the blood-brain barrier. A key point to remember is that thiopentone should be handled carefully as it can cause tissue necrosis if extravasated during administration.

## **Correct Answer:** . Thiopentone is supplied as a powder.