Objectives Hot melt extrusion (HME) as a technique for producing amorphous solid dispersion (ASD) has been widely used in pharmaceutical research. The biggest challenge for the application of HME is the thermal degradation of drug, poor physical stability of ASD and precipitation of drug during dissolution. Interactions between drugs and polymers may play an important role in overcoming these barriers. In this review, influence of drug-polymer interactions on HME and the methods for characterizing the drug-polymer interactions were reviewed. Key findings Strong drug-polymer interactions, especially ionic interactions and hydrogen bonds, are helpful to improving the thermal stability of drug during HME, enhancing the physical stability of ASD during storage and maintaining supersaturated solution after dissolution in gastrointestinal tract. The interactions can be quantitatively and qualitatively characterized by many analysing methods. Conclusions As many factors collectively determine the properties of HME products, drug-polymer interactions play an extremely important role. However, the action mechanisms of drug-polymer interactions need intensive investigation to provide more useful information for optimizing the formulation and the process parameters of HME.

This technique based on drug-polymer interactions to prepare chemically stable amorphous solid dispersions by HME provides an attractive opportunity for development of heat-sensitive drugs.

Hot melt extrusion (HME) is a powerful technology to enhance the solubility and bioavailability of poorly water-soluble drugs by producing amorphous solid dispersions. Although the number of articles and patents about HME increased dramatically in the past twenty years, there are very few commercial products by far. The three main obstacles limiting the commercial application of HME are summarized as thermal degradation of heat-sensitive drugs at high process temperature, recrystallization of amorphous drugs during storage and dissolving process, and difficulty to obtain products with reproducible physicochemical properties. Many efforts have been taken in recent years to understand the basic mechanism underlying these obstacles and then to overcome them. This article reviewed and summarized the limitations, recent advances, and future prospects of HME.

Data on Odonatoptera species from the Xiaheyan locality (Ningxia, China; Early Pennsylvanian) described so far are complemented based on abundant new material. Several taxonomic and nomenclatural adjustments are proposed. The species <i>Tupus readi</i> Carpenter, 1933 is transferred to the genus <i>Shenzhousia</i> Zhang & Hong, 2006 in Zhang et al. (2006), and therefore should be referred to as <i>Shenzhousia readi</i> (Carpenter, 1933) n. comb. The monotypic genus <i>Sinomeganeura</i> Ren et al., 2008 is synonymized with <i>Oligotypus</i> Carpenter, 1931. As a consequence the type species of the former must be referred to as <i>Oligotypus huangheensis</i> (Ren et al., 2008) n. comb. The monotypic genus <i>Paragilsonia</i> Zhang, Hong & Su, 2012 in Su et al. (2012) is synonymized with <i>Tupus</i> Sellards, 1906. As a consequence the type-species of the former is to be referred to as <i>Tupus orientalis</i> (Zhang, Hong & Su, 2012 in Su et al. (2012)) n. comb. The monotypic genus <i>Sinierasiptera</i> Zhang, Hong & Su, 2012 in Su et al. (2012) is synonymized with <i>Erasipterella</i> Brauckmann, 1983. As a consequence the type-species of the former is to be referred to as <i>Erasipterella jini</i> (Zhang, Hong & Su, 2012 in Su et al. (2012)) n. comb. In addition <i>Aseripterella sinensis</i> n. gen. et sp. and <i>Sylphalula laliquei</i> n. gen. et sp. are described. The "strong oblique distal" cross-vein, located in the area between RA and RP is found to occur more extensively than previously expected. It is believed to be a structure distinct from the subnodal cross-vein, and therefore deserves to be referred to by a distinct name (viz. "postsubnodal cross-vein"). Odonatoptera from the Xiaheyan locality cover a broad range of sizes. Factors that could have promoted the evolution of large-sized Odonatoptera are briefly reviewed. The permissive conditions prevailing during the Pennsylvanian, and the existence of an elaborated food web, are emphasized as putative positive factors. The new taxonomic treatment suggests that genera documented in the Lower Permian, such as <i>Shenzhousia</i> and <i>Oligotypus</i>, stem from the early Pennsylvanian, and implies a high resilience of these taxa when facing the Pennsylvanian–Permian environmental perturbations. <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.201300006" target="_blank">10.1002/mmng.201300006</a>