After selecting the volunteers, Metoprolol succinate drug manufactured by Raha pharmaceutical Company from Iran and FDA approved Metoprolol succinate will be prescribed to them orally in two doses with an interval of 7 days. Volunteers are blinded. For example, if in the first period of the drug administration, the volunteer received the drug manufactured by Raha pharmaceutical company, in the next turn, the volunteer will receive FDA approved Metoprolol succinate . Each time the amount of 6 cc of blood before drug administration and at times of 0, 1, 2, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 9, 10, 11, 12, 14, 24, 36, 48 hour, It will be taken from the volunteers 24 and 48 hours after the medication is prescribed. Samples were collected in Anticoagulant tube collection tubes. The tubes were centrifuged and plasma samples were stored at -80 ℃ . Finally, the amount of drug in each sample is determined by Lc Mass Mass equipment.