How much propranolol can be taken at one time?

Depend on use: Propanolol has many indications, including Hypertension, angina, Migraine Prevention, Thyrotoxicosis, etc, so depending on what is being used for, the maximum pharmacological dose varies. For example , for hypertension max is 640 mg per day, while for other consitions may only be recommended max 240-320 mg, or as the patient can tolerate, based on its side effects.