Drugs, oxidizing, solid

The NMR method was used to determine the evolution of the amorphous fraction in a trehalose powder, during a milling procedure which ultimately leads to a fully amorphous state. The purpose of the study was to determine quantitatively the amorphous fraction in crystalline-amorphous powder mixtures of trehalose, in order to assess the ability of the C NMR technique for quantitative amorphous characterisation. Poly(ethylene oxide) (PEO) was tested as a polymer matrix for solid dispersion to enhance drug bioavailability. Solid-state NMR, X-ray diffraction, and transmission electron microscopy were utilised to characterise the high miscibility between PEO and ketoprofen, a model for crystalline drugs with poor water solubility. ... 

Schachter DM, Xiong JC, Tirol GC. Solid state NMR perspective of drug-polymer solid solutions a model system based on poly(ethylene oxide). Int. J. Pharm. 2004 281 89-101. 

The mitomycins do not react directly with DNA, but require prior activation by reduction of the quinone. This property of bioreductive activation has inspired the design and development of synthetic anticancer drugs that are also activated by reduction, as this is expected to confer a degree of tumor selectivity [45, 46]. Many solid tumors are short of oxygen relative to normal tissue, so reductive activation of the mitomycins and other bioreductive drugs can proceed in tumors, while it is inhibited by the oxidizing environments in normal tissues. 

H.17 The psychoactive drug sold as methampheramine ( speed ), CI0H,N, undergoes a series of reactions in the body the net result of these reactions is the oxidation of solid methamphetamine by oxygen gas to produce carbon dioxide gas, liquid water, and nitrogen gas. Write the balanced equation for this net reaction. 

The formation of peroxides and formaldehyde in the high-purity polyoxyethylene surfactants in toiletries has been shown to lead to contact dermatitis [31], Peroxides in hydrogenated castor oil can cause autoxidation of miconazole [32], Oxidative decomposition of the polyoxyethylene chains occurs at elevated temperature, leading to the formation of ethylene glycol, which may then be oxidized to formaldehyde. When polyethylene glycol and poloxamer were used to prepare solid dispersions of bendroflumethiazide, a potent, lipophilic diuretic drug, the drug reacted with the formaldehyde to produce hydroflumethiazide [33],... 

The sample temperature is increased in a linear fashion, while the property in question is evaluated on a continuous basis. These methods are used to characterize compound purity, polymorphism, solvation, degradation, and excipient compatibility [41], Thermal analysis methods are normally used to monitor endothermic processes (melting, boiling, sublimation, vaporization, desolvation, solid-solid phase transitions, and chemical degradation) as well as exothermic processes (crystallization and oxidative decomposition). Thermal methods can be extremely useful in preformulation studies, since the carefully planned studies can be used to indicate the existence of possible drug-excipient interactions in a prototype formulation [7]. 

For fenfluramine, MDMA and methysergide, in vivo oxidation gives rise to a more potent 5-HT2B receptor agonist than the parent compound. The oxidized nitrogen is indicated by a solid arrow. Note that all drugs fall into one of the two structural classes phenylisopropylamines (top) and ergolines (bottom). 

The candidate method is used to support drug synthesis, excipient compatibility, and ultimately to evaluate candidate formulations. Such support typically involves analyses of stressed materials to identify degradation trends. These studies are conducted in the solid state by exposing the DS and DP to relative humidity, temperature, light, and oxidizing... 

A preservative is a substance that prevents or inhibits microbial growth and extends the shelf life of the drug products. In most pharmaceutical drug products, only a few compounds are typically selected as preservatives. For efficiency, a generic method should be developed for the types of preservatives that are more commonly used. For example, butylated hydroxytoluene (BHT) is an antioxidant commonly used in many solid dosage formulations to retard oxidative degradation of the excipients. 

The solid matrix of SLN protects the drug from hydrolysis and oxidation. Chemical stability of tocopherol and retinol improves considerably [17,39], with tocopherol improving by 57% compared with an aqueous dispersion. The degree of retinol stabilization depends on the nature of lipid and surfactant [39]. For each drug, the optimal preparation has to be defined individually. 

Drugs may be solid at room temperature (eg, aspirin, atropine), liquid (eg, nicotine, ethanol), or gaseous (eg, nitrous oxide). These factors often determine the best route of administration. The most common routes of administration are described in Chapter 3. The various classes of organic compounds—carbohydrates, proteins, lipids, and their constituents—are all represented in pharmacology. 

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