## **Core Concept**
Tetanus is a bacterial infection caused by *Clostridium tetani*, characterized by muscle stiffness and spasms. The management of tetanus primarily involves supportive care and specific treatments to neutralize the toxin. The drug of choice for treating tetanus should effectively counteract the effects of the toxin.

## **Why the Correct Answer is Right**
The correct answer, **D. Diazepam**, is a benzodiazepine that is effective in managing muscle spasms associated with tetanus. Diazepam enhances the effect of gamma-aminobutyric acid (GABA) in the brain, which helps in reducing muscle spasms and anxiety. It is often used in the intensive care of patients with tetanus to control muscle rigidity and spasms.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Penicillin is an antibiotic that can be used to treat the bacterial infection but does not directly counteract the toxin's effects on the nervous system.
- **Option B:** Tetanus toxoid is used for immunoprophylaxis, not for the treatment of established tetanus infection.
- **Option C:** Phenobarbitone (phenobarbital) is a barbiturate that can be used for sedation but is not the first choice for managing muscle spasms in tetanus.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the management of tetanus also includes wound care, administration of tetanus immunoglobulin to neutralize circulating toxin, and supportive care such as maintaining a patent airway and adequate nutrition. Diazepam is specifically useful for controlling muscle spasms.

## **Correct Answer:** D. Diazepam.