RESUMO
The achievement of rapid hemostasis represents a long-term trend in hemostatic research. Specifically, composite materials are now the focus of attention, based on the given issues and required properties. In urology, different materials are used to achieve fast and effective hemostasis. Additionally, it is desirable to exert a positive influence on local tissue reaction. In this study, three nonwoven textiles prepared by a wet spinning method and based on a combination of hyaluronic acid with either oxidized cellulose or carboxymethyl cellulose, along with the addition of etamsylate, were introduced and assessed in vivo using the rat partial nephrectomy model. A significantly shorter time to hemostasis in seconds (p < 0.05), was attributed to the effect of the carboxymethyl cellulose material. The addition of etamsylate did not noticeably contribute to further hemostasis, but its application strengthened the structure and therefore significantly improved the effect on local changes, while also facilitating any manipulation by the surgeons. Specifically, the hyaluronic acid supported the tissue healing and regeneration, and ensured the favorable results of the histological analysis. Moreover, the prepared textiles proved their bioresorbability after a three-day period. In brief, the fabrics yielded favorable hemostatic activity, bioresorbability, non-irritability, and had a beneficial effect on the tissue repair.
RESUMO
Supersaturation and precipitation are common limitations encountered especially with poorly soluble basic drugs. The aims of this work were to explore the pattern of dissolution and precipitation of poorly soluble basic drugs using a United States Pharmacopoeia (USP) IV dissolution apparatus and to compare it to the widely used USP II dissolution apparatus. In order to investigate the influence of gastric emptying time on bioavailability, tables of two model drugs (dipyridamole 100 mg and cinnarizine 15 mg) were investigated and pH change from 1.2 to 6.8 were achieved after 10, 20 or 30 min using USP II or USP IV dissolution apparatuses. Using USP II, dipyridamole and cinnarizine concentrations dropped instantly as a result of drug precipitation with drug crystals evident in the dissolution vessel. At pH change times of 10, 20 and 30 min, the total amount of dissolved drug was dependent on pH change time. Using USP IV, at a flow rate of 8 ml/min, it was possible to have comparable release to agitation at 50 rpm using USP II suggesting that comparable hydrodynamic forces are possible. No drop in drug percentage occurs as the dissolved fraction was readily emptied from the flow cell, preventing drug accumulation in the dissolution medium. However, a negligible percentage of drug release took place following pH change. In conclusion, the use of the flow-through cell dissolution provided laminar flow, use of realistic fluid volumes and avoided precipitation of dissolved drug fraction in the gastric phase as it is discharged before pH change.