Final answer:
For a patient in cardiac arrest with refractory ventricular fibrillation, the first drug to administer according to ACLS guidelines is epinephrine 1 mg IV/IO.
Step-by-step explanation:
If a patient is in cardiac arrest with ventricular fibrillation (V-fib) that is refractory to a second shock, the first-line medication recommended according to Advanced Cardiovascular Life Support (ACLS) protocol is epinephrine 1 mg IV/IO. This should be administered rapidly and followed according to ACLS algorithm guidelines. Options A (Atropine), C (Lidocaine), and D (Sodium bicarbonate) are not first-line medications for refractory V-fib. Specifically, atropine is not recommended for treatment of V-fib, lidocaine may be considered if amiodarone is not available, and sodium bicarbonate is used in specific circumstances such as hyperkalemia or tricyclic antidepressant overdose but not typically in the immediate management of V-fib.