**Core Concept**
Neonatal seizures are a common neurological emergency in newborns, often caused by hypoxic-ischemic encephalopathy, infection, or metabolic disorders. The drug of choice for treating neonatal seizures should have a favorable safety profile, minimal side effects, and ability to rapidly control seizure activity.

**Why the Correct Answer is Right**
Phenytoin is the preferred antiepileptic drug for neonatal seizures due to its rapid onset of action, efficacy, and relatively safe profile in this age group. Phenytoin acts by blocking voltage-gated sodium channels, which reduces neuronal excitability and prevents seizure activity. It is administered as a loading dose to achieve therapeutic levels quickly, followed by a maintenance dose to sustain control of seizures.

**Why Each Wrong Option is Incorrect**
**Option A:** Phenobarbital is a common alternative for neonatal seizures, but it is not the first-line treatment due to its sedative effects and slower onset of action compared to phenytoin.
**Option B:** Midazolam is a benzodiazepine used for acute seizure control, but it is not the preferred choice for neonatal seizures due to its short duration of action and potential for respiratory depression.
**Option C:** Levetiracetam is an antiepileptic drug used in various seizure disorders, but it is not the standard treatment for neonatal seizures due to limited data on its efficacy and safety in this age group.

**Clinical Pearl / High-Yield Fact**
When treating neonatal seizures, it's essential to monitor EEG and serum drug levels closely to optimize therapy and minimize side effects. Phenytoin's effectiveness is directly related to its plasma concentration, so regular monitoring is crucial to achieve therapeutic levels.

**Correct Answer: D. Phenytoin**