Oxidation, drug stability

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. 

Carstensen, J. T. (2000), Solution Kinetics Kinetic pH profiles Oxidation in solution Catalysis, Complexation, and Photolysis, in Carstensen, J.T. and Rhodes, C.T., Eds., Drug Stability, Principle and Practice, 3rd ed., Marcel Dekker, New York, Chapters 2-5, pp. 19-143. 

Lombardo, F., and Campos, G. (2004). How do we study oxidative chemical stability in discovery Some ideas, trials, and outcomes. In Pharmaceutical Profiling in Drug Discovery for Lead Selection (Borchardt, R. T., Kerns, E. H., Lipinski, C. A., Thakker, D. R., and Wang, B. Eds.). AAPS Press, Arlington, VA, pp. 183-194. 

Yong et ah [175] developed an effective omeprazole buccal adhesive tablet with excellent bioadhesive force and good drug stability in human saliva. The omeprazole buccal adhesive tablets were prepared with various bioadhesive polymers, alkali materials, and croscarmellose sodium. Their physicochemical properties, such as bioadhesive force and drug stability in human saliva, were investigated. The release and bioavailability of omeprazole delivered by the buccal adhesive tablets were studied. As bioadhesive additives for omeprazole tablet, a mixture of sodium alginate and hydroxypropylmethyl cellulose was selected. The omeprazole tablets prepared with bioadhesive polymers alone had bioadhesive forces suitable for a buccal adhesive tablet, but the stability of omeprazole in human saliva was not satisfactory. Magnesium oxide is an alkali stabilizer for omeprazole buccal adhesive tablets. Croscarmellose sodium enhanced the release of omeprazole from the tablets but it decreased the bioadhesive forces and stability of omeprazole tablets in human saliva. 

Stewart PJ, Tucker IG. Prediction of drug stability. Part 3 oxidation and photolytic degradation. Aus J Hosp Pharm 1985 15(2) 111-117. 

Enhanced drug stability (protection against oxidation, photodegradation, and hydrolysis in lipophilic systems). 

Stewart, PJ. and Tucker, I.G. (1985) Prediction of drug stability. III. Oxidation and photolytic degradation, Aust. J. Pharm., 15, 111-117. 

M. J. Kaufman, Applications of oxygen polarography to drug stability testing and formulation development Solution-phase oxidation of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, Pharm. Res. 7, 289-292(1990). 

The common reaction mechanisms of chemical degradation of pharmaceutical compounds include hydrolysis, oxidation, isomerization/epimerization, decarboxylation, rearrangement, dimerization/polymerization, photolysis, and reactions with excipients and salt forms. Examples are shown in Table 7.6 Interested readers should consult reference books on drug stability for more information on degradation pathways [13, 22]. 

To enhance the desirable properties of a polymer as a matrix for a controlled drug delivery system, efforts have been made to improve its hydrophilicity, biodegradation rate, and drug stability. Hydrophilic blocks play vital role in polymeric drug delivery systems, for example, poly(ethylene oxide)... 

Drug Stability - The oxidation of apomorphine by molecular oxygen is apparently first order in apomorphine, does not exhibit a lag time, and is catalyzed by copper (II) and iron (11). The effect of these ions is negated by the use of 0.01% sodium edetate. Apomorphine can be stored at room temperature for fifteen years or more if its solutions are prepored under nitrogen at pH 3, with sodium metabisuifite and hydrochloric acid. 

Occurrence of the above metabolites was also monitored in human urine. As the main metabolites 2-bromolysergic acid and its 8-epimer and the respective amides were found (54c, d, g, h) (Maurer et al., 1983). It is interesting that oxidative attack did not start at ergoline ring, especially in pos. 2 or 3. Bromination probably improves the drug stability. 

Imidazole, 1 -hydroxy-2,4,5-triphenyl-3-oxides reactions, S, 455 Imidazole, iodo-nitrodehalogenation, 5, 396-397 Imidazole, 1-iodo-reactions, S, 454 stability, S, 110 Imidazole, 2-iodo-synthesis, S, 401 Imidazole, N-iodo-, S, 393 reactions, 5, 454 Imidazole, 4-iodo-5-methyl-iodination, 5, 400 Imidazole, 2-isopropyl-4-nitro-N-nitration, 5, 351 Imidazole, 2-lithio-reactions, S, 106, 448 Imidazole, 2-mercapto-l-methyl-as antithyroid drug, 1, 171 mass spectra, 5, 358 Imidazole, 1-methoxymethyl-acylation, S, 402 Imidazole, 5-methoxy-l-methyl-reactions... 

---