Pediatric dosing for locally acting drugs in submissions to the U.S. Food and Drug Administration between 2002 and 2020.

Deriving pediatric doses for locally acting drugs (LADs) presents a unique challenge because limited systemic exposure hinders commonly used approaches such as pharmacokinetic matching to adults. This study systematically evaluated drug development practices used for pediatric dose selection of LADs approved by the U.S. Food and Drug Administration from 2002 to 2020. The three study objectives were: (1) to determine the dose selection approach for the labeled pediatric dose, (2) to examine the studied pediatric dose(s), and (3) to evaluate the characteristics of the pediatric clinical programs used to support the labeled pediatric dose. A total of 187 pediatric submissions were characterized for the labeled and studied pediatric doses of LADs. The pediatric dose was predominantly labeled as a flat dose (91%) and at a single-dose level (67%) similar to adults. The majority (68.4%) of the submissions had the same labeled dose for pediatrics and adults. Independent pharmacodynamic/efficacy studies in pediatric patients commonly (64.2%) provided supportive evidence for the labeled pediatric dose. Inhalation, nasal, and injectable submissions had the highest number of clinical trials, lowest usage of an extrapolation of efficacy approach, and utilized diverse approaches in selecting the studied pediatric doses. This article highlights approaches for LAD dosing in pediatric patients and can be used to inform drug development of these products in the pediatric population.

Quantifying prefibrillar amyloids in vitro by using a "thioflavin-like" spectroscopic method.

In Alzheimer's disease (AD) and other neurodegenerative disorders, proteins accumulate into ordered aggregates, called amyloids. Recent evidence suggests that these structures include both large, insoluble fibrils and smaller, prefibrillar structures, such as dimers, oligomers, and protofibrils. Recently, focus has shifted to the prefibrillar aggregates because they are highly neurotoxic and their levels appear to correlate with cognitive impairment. Thus, there is interest in finding methods for specifically quantifying these structures. One of the classic ways of detecting amyloid formation is through the fluorescence of the benzothiazole dye, thioflavin T (ThT). This reagent has been a "workhorse" of the amyloid field because it is robust and inexpensive. However, one of its limitations is that it does not distinguish between prefibrillar and fibrillar aggregates. We screened a library of 37 indoles for those that selectively change fluorescence in the presence of prefibrillar amyloid-beta (Abeta). From this process, we selected the most promising example, tryptophanol (TROL), to use in a quantitative "thioflavin-like" assay. Using this probe in combination with electron microscopy, we found that prefibrils are largely depleted during Abeta aggregation in vitro but that they remain present after the apparent saturation of the ThT signal. These results suggest that a combination of TROL and ThT provides greater insight into the process of amyloid formation by Abeta. In addition, we found that TROL also recognizes other amyloid-prone proteins, including ataxin-3, amylin, and CsgA. Thus, this assay might be an inexpensive spectroscopic method for quantifying amyloid prefibrils in vitro.

Cytochrome b5 reductase and the control of lipid metabolism and healthspan.

Cytochrome b5 reductases (CYB5R) are required for the elongation and desaturation of fatty acids, cholesterol synthesis and mono-oxygenation of cytochrome P450 enzymes, all of which are associated with protection against metabolic disorders. However, the physiological role of CYB5R in the context of metabolism, healthspan and aging remains ill-defined. We generated CYB5R-overexpressing flies (CYB5R-OE) and created a transgenic mouse line overexpressing CYB5R3 (CYB5R3-Tg) in the C57BL/6J background to investigate the function of this class of enzymes as regulators of metabolism and age-associated pathologies. Gender- and/or stage-specific induction of CYB5R, and pharmacological activation of CYB5R with tetrahydroindenoindole extended fly lifespan. Increased expression of CYB5R3 was associated with significant improvements in several metabolic parameters that resulted in modest lifespan extension in mice. Diethylnitrosamine-induced liver carcinogenesis was reduced in CYB5R3-Tg mice. Accumulation of high levels of long-chain polyunsaturated fatty acids, improvement in mitochondrial function, decrease in oxidative damage and inhibition of chronic pro-inflammatory pathways occurred in the transgenic animals. These results indicate that CYB5R represents a new target in the study of genes that regulate lipid metabolism and healthspan.