Bioequivalence Study of Digoxin Tablet in Healthy Subjects

The study followed an open-label, randomized, single-dose (0.25mg), four-period full-replicate design encompassing both fasted and fed conditions. Subjects were randomized into two sequences, labeled as group A (TRTR) and group B (RTRT), for the four sessions. By the use of a random table produced by SAS statistical software, the individuals were assigned at random to administer a single-dose (0.25mg) of either the reference or the test formulation of digoxin tablets. During the fasted study phase, participants were randomly administered digoxin tablets after an overnight fast of a minimum of 10 hours, and fasting continued for 4 hours post dose. During the fed trial, subjects consumed a high-fat breakfast 30 minutes before administering digoxin tablets, which consisted of approximately 500 to 600 kcal of fat, 150 kcal of protein, and 250 kcal of carbohydrates, totaling around 800 to 1000 kcal calories. The breakfast must be finished within 30 minutes. Digoxin tablets were administered to each subject in a single dosage with 240 mL of water. Each subject was assigned equitably and at random to one of the two groups. A 14-day washout period was implemented between each period. In the fasted study, blood samples were collected at various time points: predose, 0.17, 0.33, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 3.5, 4, 5, 6, 8, 12, 24, 48, 72, 96, 120 and 144 hours after dosing. Similarly, in the fed study, blood samples were collected at predose and at 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5, 3, 3.5, 4, 5, 6, 8, 12, 24, 48, 72, 96, 120 and 144 hours after dosing. Following collection, the samples underwent centrifugation at 1700g for 10 minutes at 4℃. The resulting supernatant was then divided into two aliquots and stored at -80℃ until further analysis was conducted. A validated high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) method was employed to assess the level of digoxin in plasma samples. The PK analysis of the plasm