RESUMEN
Iron deficiency is the principal cause of nutritional anemia and it constitutes a major health problem, especially during pregnancy. Despite the availability of various non-invasive traditional oral dosage forms such as tablets, capsules, and liquid preparations of iron, they are hard to consume for special populations such as pregnant women, pediatric, and geriatric patients with dysphagia and vomiting tendency. The objective of the present study was to develop and characterize pullulan-based iron-loaded orodispersible films (i-ODFs). Microparticles of iron were formulated by a microencapsulation technique, to mask the bitter taste of iron, and ODFs were fabricated by a modified solvent casting method. Morphological characteristics of the microparticles were identified by optical microscopy and the percentage of iron loading was evaluated by inductively coupled plasma optical emission spectroscopy (ICP-OES). The fabricated i-ODFs were evaluated for their morphology by scanning electron microscopy. Other parameters including thickness, folding endurance, tensile strength, weight variation, disintegration time, percentage moisture loss, surface pH, and in vivo animal safety were evaluated. Lastly, stability studies were carried out at a temperature of 25 °C/60% RH. The results of the study confirmed that pullulan-based i-ODFs had good physicochemical properties, excellent disintegration time, and optimal stability at specified storage conditions. Most importantly, the i-ODFs were free from irritation when administered to the tongue as confirmed by the hamster cheek pouch model and surface pH determination. Collectively, the present study suggests that the film-forming agent, pullulan, could be successfully employed on a lab scale to formulate orodispersible films of iron. In addition, i-ODFs can be processed easily on a large scale for commercial use.
RESUMEN
A number of Protein Data Bank (PDB) entries contain heteroatoms defined as HETATM. These include the atomic co-ordinates mainly for heteroatom groups, such as cofactors, coenzymes, prosthetic groups, metal ions, sugars, drugs, peptides, heavy-atom derivatives, non-standard amino acid residues/nucleotides, water molecules and so on. In order to evaluate the different heteroatom (Het) groups and their distribution in protein tertiary structure, we have extracted these from all proteins in the PDB and provided the data in an easily accessible format at the following website. The data can be queried on the PDB code, protein name/description, Het Group code or Het Group name. Further, we have also developed a web-based software application that reports neighbouring atoms evaluated by a "user-defined" distance cut-off value (in Angstrom units), either between a specific Het Group or all Het Groups in a given PDB with amino acid residues and water molecules in the corresponding protein, or neighbours for only all the amino acid residues in the given PDB with respect to Het Groups and water molecules. Together, the database and software applications are useful to gather information that can be further analyzed in order to obtain insights into the preferred interactions of heteroatom groups in proteins, study their binding mode, design novel molecules or to annotate protein function.