Spectroscopy is the study of matter interacting with electromagnetic radiation (e.g., light). The electromagnetic spectrum in Figure 1 illustrates the many different types of electromagnetic radiation, including gamma rays (γ-rays), X-rays, ultraviolet (UV) radiation, visible light, infrared (IR) radiation, microwaves, and radio waves. The frequency (ν) and wavelength (λ) ranges associated with each form of radiant energy are also indicated in Figure 1.

Introduction to Spectroscopy

The Food and Drug Administration (FDA) is a regulatory agency of the United States federal government This article describes the scope of work of each of the FDA's major components, and addresses the role of statisticians at FDA


Keywords:

drug regulation;
clinical trials;
medical devices;
safety;
bioassay

Food and Drug Administration (FDA)

Volumes in this widely revered series present comprehensive reviews of drug substances and additional materials, with critical review chapters that summarize information related to the characterization of drug substances and excipients. This organizational structure meets the needs of the pharmaceutical community and allows for the development of a timely vehicle for publishing review materials on this topic. The scope of the Profiles series encompasses review articles and database compilations that fall within one of the following six broad categories: Physical profiles of drug substances and excipients; Analytical profiles of drug substances and excipients; Drug metabolism and pharmacokinetic profiles of drug substances and excipients; Methodology related to the characterization of drug substances and excipients; Methods of chemical synthesis; and Reviews of the uses and applications for individual drug substances, classes of drug substances, or excipients. * Contributions from leading authorities * Informs and updates on all the latest developments in the field

Profiles of Drug Substances, Excipients, and Related Methodology

High temperature processing is essential for the preparation of apatites for biomaterials, lighting, waste removal and other applications. This requires a good understanding of the thermal stability and transitions upon heating. The most widely used is hydroxyapatite (HAp), but increasing interest is being directed to fluorapatite (FAp) and chlorapatite (ClAp). The structural modifications for substitutions are discussed to understand the temperature processing range for the different apatites. This is based on a review of the literature from the past few decades, together with recent research results. Apatite thermal stability is mainly determined by the stoichiometry (Ca/P ratio and structural substitutions) and the gas composition during heating. Thermal stability is lowered the most by a substitution of calcium and phosphate, leading to loss in phase stability at temperatures less than 900 °C. The anions in the hexagonal axis, OH in HAp, F in FAp and Cl in ClAp are the last to leave upon heating, and prevention of the loss of these groups ensures high temperature stability. The information discussed here will assist in understanding the changes of apatites during heating in calcination, sintering, hydrothermal processing, plasma spraying, flame pyrolysis, and other high-temperature processes.

A Review on the Thermal Stability of Calcium Apatite

What is calcium carbonate? Calcium carbonate is a dietary supplement used to increase calcium in your body. Calcium is needed for healthy bones, muscles, nervous system and heart. Also, calcium carbonate is used as an antacid to relieve heartburn, acid indigestion and upset stomach. Calcium carbonate comes in different forms, including tablet, chewable tablet, capsule, and liquid. It can also be an ingredient in other over the counter products.

Calcium Carbonate～最經濟的鈣鹽補充劑

Clays have played an important role in medicine since the dawn of mankind and are still applied widely as active ingredients and/or excipients in pharmaceutical formulations Due to their outstanding properties of large retention capacity, swelling and rheological properties, and relative low cost, they have been used widely as advanced carriers for the efficient delivery of drugs by modifying their release (rate and/or time), increasing the stability of the drug, improving the dissolution profile of a drug, or enhancing their intestinal permeability In addition, recent studies have shed new light on the potential of clay minerals in the nanomedicine field due to their biocompatibility, beneficial effects of clay nanoparticles on cellular adhesion, proliferation, and differentiation Use as active ingredients and excipients are exerted via the oral and topical administration pathways Skin drug delivery represents an attractive alternative to the oral route, providing local and/or systemic drug delivery Due to their complex structures, however, most drugs penetrate the human skin only with difficulty Enormous efforts have been invested, therefore, in developing advanced drug delivery systems able to overcome the skin barrier Most strategies require the use of singular materials with new properties In particular, and on the basis of their inherent properties, clay minerals are ideal candidates for the development of intelligent skin drug delivery systems In this article, the properties of clay materials and their use in the skin-addressed pharmaceutical field are reviewed A brief introduction of skin physiology and biopharmaceutical features of penetration by a drug through the skin layers is also included and is designed to shed light on the optimum properties of ideal nanosystems for advanced skin drug delivery Special attention is devoted to the pharmacological functions of clays and their biomedical applications in pelotherapy, wound healing, regenerative medicine, antimicrobial, and dermocosmetics

Clay Minerals in Skin Drug Delivery

Assessment of halloysite nanotubes as vehicles of isoniazid.

Adsorption and characterization of palygorskite-isoniazid nanohybrids

Background: Chronic cutaneous wounds represent a major issue in medical care and are often prone to infections.

Purpose: The aim of this study was the design of a clay mineral-drug nanocomposite based on montmorillonite and norfloxacin (NF, antimicrobial drug) as a powder for cutaneous application, to enhance wound healing in infected skin lesions.

Methods: The nanocomposite has been prepared by means of an intercalation solution procedure. Adsorption isotherm, solid-state characterization of the nanocomposite, drug loading capacity and its release have been performed. Moreover, cytocompatibility, in vitro fibroblast proliferation and antimicrobial activity against Pseudomonas aeruginosa and Staphylococcus aureus were assessed.

Results: The clay drug adsorption isotherm demonstrates that the mechanism of NF intercalation into montmorillonite galleries is the adsorption as one single process, due to the charge–charge interaction between protonated NF and negatively charged montmorillonite edges in the interlayer space. Nanocomposite is biocompatible and it is characterized by antimicrobial activity greater than the free drug: this is due to its nanostructure and controlled drug release properties.

Conclusion: Considering the results obtained, NF–montmorillonite nanocomposite seems a promising tool to treat infected skin lesions or skin wounds prone to infection, as chronic ulcers (diabetic foot, venous leg ulcers) and burns.

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Fátima García-Villén

Papers

Clay Minerals in Skin Drug Delivery

Assessment of halloysite nanotubes as vehicles of isoniazid.

Adsorption and characterization of palygorskite-isoniazid nanohybrids

Montmorillonite-norfloxacin nanocomposite intended for healing of infected wounds.

Crosslinked palygorskite-chitosan beads as diclofenac carriers