Cardioplegia, also known as propranolol, starts to work 1 to 1.5 hours after oral intake, and the half-life of the drug is 2 to 3 hours. Propranolol belongs to the beta-blocker, belongs to the short-acting anti-arrhythmic and antihypertensive drugs, oral absorption is relatively rapid, 1 to 1.5 hours after taking the drug began to play a role in the drug, the drug’s half-life can last 2 to 3 hours, but the effect of the drug can last for about 6 hours, you need to take three times a day orally. Propranolol belongs to the western prescription drugs, the main clinical indications are hypertension, coronary heart disease, tachyarrhythmia, etc., the adverse effects of the drug are dizziness, bradycardia, dyspnea, cold limbs, etc., allergic to the drug components, bronchial asthma, cardiogenic shock, severe heart failure is prohibited in patients. Propranolol belongs to the prescription drugs, if there is any discomfort, it is recommended to consult a doctor in a timely manner and follow the doctor’s instructions.