A review with 310 references. Photochemical degradation is likely to be an important loss mechanism for many pharmaceutical pollutants in surface waters. This review summarizes the current knowledge of the photochemical behavior of pharmaceuticals and highlights the use of the fundamental photochemistry and phototoxicity literature to help understand and predict the aquatic fate of pharmaceuticals. Naproxen and diclofenac are shown to exemplify the idea that photochemical behavior obtained from fundamental photochemistry studies can be related to environmental conditions. There are, however, numerous compounds that have been found in environmental matrices for which no photochemistry data relatable to environmental conditions are available. It will be necessary to combine the results available in the large body of fundamental photochemistry and phototoxicity literature with laboratory and field experiments designed to determine direct and indirect photolysis rates and to identify photoproducts. This course will lead to a thorough understanding of the role of photodegradation on the fate and impact of pharmaceutical pollutants.

Photodegradation of pharmaceuticals in the aquatic environment: A review

Accelerated aging: prediction of chemical stability of pharmaceuticals.

Publisher Summary This chapter discusses the suramin with special reference to onchocerciasis. Suramin is a pinkish white flocculent powder, with high solubility in water (more than 10% w/v); its solutions are stable to boiling. Suramin is hygroscopic and absorbs moisture from the atmosphere unless kept in a desiccator; the presence of this unsuspected water may cause errors in quantitative experiments. The capacity of suramin to combine with the plasma proteins depends on the naphthylaminetrisulfonic groups. Many of the pharmacological properties of suramin, e.g., its binding to serum proteins are because of its general structure as a large molecule with many sulfonic acid groups. Suramin forms complexes with serum proteins and is then taken up into lysosomes where it accumulates, just as acidic vital dyes do. This accumulation occurs in the reticuloendothelial cells all over the body but particularly in the Kupffer cells of the liver and in the cells of the convoluted tubules of the kidney. Suramin (which has six acidic groups) combines with basic compounds such as pentamidine and homidium to give insoluble complexes that are less toxic than the parent compound. They are deposited at the site of injection and are slowly absorbed, producing prophylaxis against trypanosomes over long periods.

Suramin: with special reference to onchocerciasis.

pH-independent release of a weakly basic drug from water-insoluble and -soluble matrix tablets

Publisher Summary This chapter reviews the importance of micellar catalysis in relation to mechanistic physical–organic and bio-organic chemistry, to enable to design meaningful experiments in the area, and to guide one through the abundant literature of surfactants and solubilization. Although solubilization by surface active agents has found considerable utility in pharmaceutical and industrial processes, the attention is primarily focussed on the mechanistic aspects of micellar catalyzed organic reactions. The subject is in its rapidly growing infancy, and is scattered and involves interdisciplinary collaboration among colloid, electro, structural, biological, pharmaceutical and organic chemists. The effects of many charged macromolecules, such as polymers, on ionic reactions can be qualitatively predicted on the basis of simple electrostatic considerations analogous to those involved in Hartley's rule.

Karl Thoma

Papers

Influence of aqueous coatings on the stability of enteric coated pellets and tablets.

Retardation of weakly basic drugs with diffusion tablets

The pH-independent release of fenoldopam from pellets with insoluble film coats

The influence of formulation and manufacturing process on the photostability of tablets.

Photostabilization of drugs in dosage forms without protection from packaging materials