A 25-year-old women has worsening palpitation, tremor, insomnia, and weight loss over the last 5 months. She takes no medications. On examination, HR 120/min, BP 150/65mmHg, and BMI 20. She has lid lag and a significantly enlarged thyroid. Her hands are warm, sweat, and has fine tremor. TSH is 0.005mU/L and free T4 is 85 pmol/L. Which of the following is the best initial treatment option for this patient?