The nonvolatile vehicle would

be the PE only or the combination of PE and film forming polymer (FFP). The spray PF-06463922 System was prepared by incorporating FFP and PE into a solvent system. We used ethanol as the volatile vehicle in this study. The drug application system (Wantong Fixed Quantity Valve System Co. Ltd., Suzhou, China) consisted of a 10mL container and an actuator with the actuating volume of 100μL. Formulations were prepared with a series of Inhibitors,research,lifescience,medical batches using different PEs or FFPs according to Table 1. The chosen FFPs were based on the following criteria: drying time, cosmetical attractiveness, and outward stickiness. Table 1 Composition of investigated formulation for excipients screening. 2.4. In Vitro Skin Permeation Experiments We used three animal models for the in vitro experiments. They are

hairless mice, rat, and porcine. The procedure of the skin was as follows; the dorsal skins of hairless mice or rat were excised after sacrifice by cervical dislocation; porcine skins were obtained from young animals Inhibitors,research,lifescience,medical sacrificed at the local slaughter house. Adjacent parts of the same skin were used under different conditions to minimize the skin variability factor. Fresh prepared skins were stored in refrigerator at −20°C without repeatable freeze and thaw cycles. Prior to permeation experiments, skin was thawed and subcutaneous Inhibitors,research,lifescience,medical fat, tissue, and capillaries of skin were carefully removed. The skins were washed with normal saline solution and inspected for the integrity by microscope observation. Any skin that had low uniformity was rejected. Inhibitors,research,lifescience,medical After cutting into pieces, skin was mounted between the donor and receptor compartment of the Franz diffusion cells with

the stratum corneum facing the donor compartment. The permeation area of Franz diffusion cells was 3.14cm2 and a receiver volume was 7.0mL. Phosphate buffer saline (PBS) with PH 7.4 was used as the receiver medium. Assembled diffusion cells in triplicate were placed in a transdermal permeation diffusion instrument and maintained isothermally Inhibitors,research,lifescience,medical at 32°C. The receptor compartment was stirred with a magnetic stirrer at 220rpm. The air bubbles that remained in the receptor cell were carefully removed by gentle tilting of the diffusion cells. After the whole system was maintained at 32°C for 2h, we used micropipette to deliver medroxyprogesterone 100μL drug liquid precisely and uniformly on the skin. Samples (0.3mL) were withdrawn at 2, 4, 6, 12, and 24h for HPLC analysis and were replaced with an equivalent volume. All samples were centrifuged at 17,800×g for 3min and then supernatant was used for analysis. The cumulative amount Q (μg/cm2) of DE permeated through skin was calculated by the following equation: Qn=Cn×V0+∑i=1n−1(Ci×Vi)A, (1) where A is the effective area 3.14cm2, Vo is the volume of receptor cell 7.