For the freeze–thaw stability, the QC PD98059 supplier samples were subjected to three cycles of freeze–thaw operations in three consecutive days then analyzed against a calibration curve of the day. For long-term stability three sets of QC samples were prepared, the first set was analyzed and calculated against calibration curve of the day. The other two sets were stored at −20 °C for 50 days then analyzed and calculated against calibration curve of the day. The pharmacokinetics of AT and EZ from two commercially available combination products A and B was compared following the administration of single doses comprising AT 40 mg and EZ 10 mg, using a non-blind, two-treatment, two-period, randomized, crossover design. Twenty-four healthy male

volunteers participated in this comparative study after giving informed written consent and undergoing physical, complete haematological and biochemical examinations. They were randomly assigned to one of two groups of equal size. Their mean age was 34 ± 4 years, mean body mass was 71.4 ± 7.2 kg and mean height was 173.0 ± 4.5 cm. The study was approved by the Ethics Committee

for protection of human subjects (Faculty of Pharmacy, Cairo University, Cairo, Egypt) and the protocol complies with the declarations of Helsinki and Tokyo for humans. Instructions were given GSK1120212 to all subjects to abstain from taking medicines and smoking for 1 week before the beginning of the studies to the end of the test. All subjects fasted for at least 10 h before the study day14 to facilitate

the pharmacokinetic and bioavailability studies of this combination in humans. The study was performed in two phases: phase I, half the number of volunteers received product B (test formulation) and the remainder received product A (reference branded combination formulation). Both treatments were ingested with 200 mL of water. Food and drink (other than water, which was allowed after 2 h) were not allowed until 4 h after dosing and then a standard breakfast, lunch and dinner were given to all volunteers according to a time schedule. A washout period of one week separated the two phases. In the second phase, the reverse of randomization took place. Each group was supervised by a physician who was also responsible for their safety and collection of samples during the trial. Adverse events were 4-Aminobutyrate aminotransferase spontaneously reported or observed either by the volunteers or the physician and were recorded and evaluated. Venous blood samples (5 mL) were collected into heparinized tubes at the following set points: 0 (pre-dose), 0.5, 1, 1.5, 2, 3, 4, 5, 6, 8, 24 and 72 h after administration of each treatment. Samples were pretreated as previously mentioned. Pharmacokinetic analysis was performed by means of a model independent method using Kinetica™ 2000 computer program (USA). The maximum drug concentration (cmax, ng mL−1) and the time to reach cmax (tmax, h) were obtained from the individual plasma concentration–time curves.