Pharmacokinetics, Bioequivalence, and Safety of Esomeprazole Magnesium Enteric-Coated Capsules in Healthy Chinese Subjects.

This bioequivalence study is critically important for drug production. Recently, a local pharmaceutical company produced esomeprazole magnesium enteric-coated capsules, a major drug to help to eradicate Helicobacter pylori, but the bioequivalence is not well known. The present study aimed to evaluate the bioequivalence of the 2 esomeprazole magnesium enteric-coated capsules and their pharmacokinetics and safety in 3 biological equivalence trials: fasting, feeding, and mixing. The fasting and mixing trials used single-centered randomized, open-label, single-dose, 2-treatment, 2-period, and 2-sequence crossover design, while the fed trials used single-centered, randomized, open-label, single-dose, 2-treatment, 3-period, 3-sequence partial crossover design. For the fasting and mixing trials, each of the 32 subjects was fasted overnight prior to taking the test preparations or reference preparations. In the fed trial, 54 subjects were given a high-fat meal 1 hour before the drugs were administered. Blood specimens from all subjects were collected against the light within 14 hours, with the plasma drug concentration being detected by the validated ultra-performance liquid chromatography-tandem mass spectrometry analysis method. Geometric mean ratio of maximum concentration, the area under the concentration-time curve from time zero to the last measurable concentration, and area under the concentration-time curve from time zero to infinity with 90% confidence interval were calculated. The data from fasting, mixing, and fed trials met the bioequivalence criteria. No serious adverse reactions were found, suggesting that the test and reference preparations of esomeprazole magnesium enteric capsules have similar safety profile.

Feedback from horizontal cells to cones mediates color induction and may facilitate color constancy in rainbow trout.

Color vision is most beneficial when the visual system is color constant and can correct the excitations of photoreceptors for differences in environmental irradiance. A phenomenon related to color constancy is color induction, where the color of an object shifts away from the color of its surroundings. These two phenomena depend on chromatic spatial integration, which was suggested to originate at the feedback synapse from horizontal cells (HC) to cones. However, the exact retinal site was never determined. Using the electroretinogram and compound action potential recordings, we estimated the spectral sensitivity of the photoresponse of cones, the output of cones, and the optic nerve in rainbow trout. Recordings were performed before and following pharmacological inhibition of HC-cone feedback, and were repeated under two colored backgrounds to estimate the efficiency of color induction. No color induction could be detected in the photoresponse of cones. However, the efficiency of color induction in the cone output and optic nerve was substantial, with the efficiency in the optic nerve being significantly higher than in the cone output. We found that the efficiency of color induction in the cone output and optic nerve decreased significantly with the inhibition of HC-cone feedback. Therefore, our findings suggest not only that color induction originates as a result of HC-cone feedback, but also that this effect of HC-cone feedback is further amplified at downstream retinal elements, possibly through feedback mechanisms at the inner plexiform layer. This study provides evidence for an important role of HC-cone feedback in mediating color induction, and therefore, likely also in mediating color constancy.