After selecting the volunteers, Azithromycin drug manufactured by Mahban and Pfizer will be prescribed to them orally in two doses with an interval of 7 days. For example, if in the first period, the volunteer received the drug manufactured by Mahban, in the next turn, the volunteer will receive the drug manufactured by Pfizer. Each time the amount of 6 cc of blood before drug administration and at times of 0 ،0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 8, 12, 24, 48, 72 hour 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. equipment.