The purpose of this article is to review the suitability of the analytical and statistical techniques that have thus far been developed to assess the dissolution behavior of particles in the respirable aerodynamic size range, as generated by orally inhaled products (OIPs) such as metered-dose inhalers and dry powder inhalers. The review encompasses all analytical techniques publicized to date, namely, those using paddle-over-disk USP 2 dissolution apparatus, flow-through cell dissolution apparatus, and diffusion cell apparatus. The available techniques may have research value for both industry and academia, especially when developing modified-release formulations. The choice of a method should be guided by the question(s) that the research strives to answer, as well as by the strengths and weaknesses of the available techniques. There is still insufficient knowledge, however, for translating the dissolution data into statements about quality, performance, safety, or efficacy of OIPs in general. Any attempts to standardize a dissolution method for compendial inclusion or compendial use would therefore be premature. This review reinforces and expands on the 2008 stimulus article of the USP Inhalation Ad Hoc Advisory Panel, which "could not find compelling evidence suggesting that such dissolution testing is kinetically and/or clinically crucial for currently approved inhalation drug products."
HighlightsLinear decline in cerebellar volume in people with classical A-T across childhood.Divergent volume trajectories in children with and without A-T in the first decade.Alterations in metabolites seen in childhood A-T independent of age and volume.Fractional fourth ventricular volume predicts neurological status in childhood A-T.
Studies of distribution, extraction procedures and spiking protocols in the determination of incurred chloramphenicol residues in animal tissues have been carried out. An extraction procedure involving glucuronidase enzyme digestion was found to extract 10 times more incurred chloramphenicol from pig kidney than direct extraction without digestion. However, neither protease digestion nor ultrasonic probe treatment resulted in improved chloramphenicol extraction. Chloramphenicol was found to be inhomogeneously distributed within kidney from a treated pig. Highest concentrations were detected in the renal medulla. Muscle tissues from the same animal were found to contain a lower concentration of chloramphenicol residues, but no chloramphenicol residues were detectable in the liver. Chloramphenicol recovery from spiked pig liver was found to be lower than that from kidney, but was improved by the addition of piperonyl butoxide before extraction. This additive had no effect on recovery from spiked pig or cattle kidney. The implications of these results for regulatory surveillance of animal tissue for chloramphenicol residues are discussed.
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