A 38-year-old female has been on corticosteroids for several months to manage severe asthma exacerbations. The patient reports weight gain, feeling anxious, experiencing insomnia, and noticing increased facial hair growth. Which of the following is the most likely explanation for these symptoms?

A. Respiratory arrest and coma: These are late, life-threatening manifestations of local anesthetic systemic toxicity (LAST) that occur after CNS and cardiovascular collapse. Recognizing early signs is critical to preventing progression to this severe stage.
B. Ventricular arrhythmias and cardiac arrest: These are also late signs of LAST, resulting from the anesthetic’s depressant effects on cardiac conduction. By the time these occur, toxicity is advanced and may require immediate resuscitation measures.
C. Hypotension and tachycardia: Although cardiovascular symptoms may eventually develop, they are typically preceded by neurological signs. Early identification and management of CNS symptoms can often prevent progression to cardiovascular compromise.
D. Tinnitus, metallic taste, and perioral numbness: These are classic early signs of LAST and indicate CNS involvement. They often occur within minutes of administration and should prompt immediate intervention to stop drug absorption and initiate supportive care.

A. Intramuscular Phenobarbital: While effective as an anticonvulsant, phenobarbital has a slower onset of action and is not the preferred first-line treatment for acute seizures. It is more commonly used in refractory cases or for long-term seizure control.
B. Intravenous Lorazepam: Lorazepam is a benzodiazepine and the first-line treatment for active seizures, especially status epilepticus. Given IV, it acts quickly by enhancing GABA activity, which calms neuronal excitability and stops seizure activity efficiently.
C. Oral Phenytoin: Phenytoin is used for long-term seizure prevention but is not effective for terminating ongoing seizures due to its slow onset when taken orally. It may be used after benzodiazepines to prevent seizure recurrence but not as the initial agent.
D. Subcutaneous Sumatriptan: Sumatriptan is used for treating acute migraines and has no role in managing seizures. It acts on serotonin receptors to relieve migraine symptoms, not to control abnormal neuronal discharges.