Drug development reagent stability

As for all bioanalytical methods applied to support of drug development, validation of immunoassays is important. However, several validation issues need special attention for immunoassays. These include stability of the critical reagents, the curvilinear nature of the calibration curve, the greater variability of immunoassays, and, particularly important, the specificity of the assay. 

Other Fluorinated Antibiotic Drugs Flurithromydn is an erythromycin fluorinated atC-9. It was launched some years ago (Figure 8.21). Its preparation involves electrophilic fluorination of 8,9-anhydroerythromycin-6,9-hemiacetal or of erythronolide A with CFsOF, or with a N— F reagent (NFSI) (cf. Chapter 4). The advantage of the fluorine substitution is a better stability in acidic medium and an increased bioavailability. Two erythromycins fluorinated at C-14 are in clinical development HMR-3562 and HMR-3787). 

Small molecules modulating microtubule assembly have played major roles as tools in microtubule research, in a manner closely related to their chemotherapeutic interest [1], Tubulin was first purified in the last century as the colchicine-binding protein proposed to be the subunit of cellular microtubules [2], More recently, a colchicine derivative was employed to help crystallization and determine the structure of tubulin by X-ray diffraction [3], The colchicine, vinblastine [4] and paclitaxel [5] sites are main drug binding sites of tubulin, to which many other substances bind. The discovery of microtubule stabilization by paclitaxel [6] prompted its clinical development [7] and a burst of research on new MSAs, as well as the generalized use of paclitaxel or docetaxel as convenient reagents to assemble (see Fig. 1), stabilize or detect microtubules in the laboratory. One example is the development... 

After fixing all other parameters, a few other experiments were performed to ascertain the influence of the order in which reagents were added. The following order drug, ferricyanide and iron (III), followed by sulphuric acid after full colour development, gave maximum absorbance and stability, and for this reason the same order of addition was followed throughout the investigation. 

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