Franco Lombardo

ElogDoct:A tool for lipophilicity determination in drug discovery basic and neutral compounds

We present an RP-HPLC method for the determination of the octanol-water distribution coefficients at pH 7.4, as log values, for neutral and basic drugs, which combines ease of operation with high accuracy. The method is shown to work for a training set of 90 molecules comprised largely of drugs, and it was also applied to a test set of 10 proprietary compounds. This work expands the applicability of the method presented in our earlier report, for the determination of logP(oct) for neutral compounds (J. Med. Chem. 2000, 43, 2922-2928), and it offers the same general features but widens the scope. Generally, the method (i) is compound sparing (< or =1 mL of a 50-100 microg/mL solution needed), (ii) is insensitive to concentration and phase ratio effects observed in some shake-flask determinations, (iii) is amenable to rapid determinations (< or = 20 min on average), (iv) is insensitive to impurities, (v) possesses a wide lipophilicity range (>7 log units), and (vi) offers a good accuracy, (vii) an excellent reproducibility, (viii) and an excellent potential for automation. To the best of our knowledge, a similar performance, on a set of noncongeneric drugs, has not been previously reported. We refer to the value generated via this method as ElogD(oct).

Stabilization of Pharmaceuticals to Oxidative Degradation

A guide for stabilization of pharmaceuticals to oxidation is presented. Literature is presented with an attempt to be a ready source for data and recommendations for formulators. Liquid and solid dosage forms are discussed with options including formulation changes, additives, and packaging documented. In particular, selection of and methods for use of antioxidants are discussed including recommended levels.

Measurement of dissociation constants (pKa values) of organic compounds by multiplexed capillary electrophoresis using aqueous and cosolvent buffers

Evaluation of a multiplexed capillary electrophoresis (CE) method for pK(a) measurements of organic compounds, including low solubility compounds, is presented. The method is validated on a set of 105 diverse compounds, mostly drugs, and results are compared to literature values obtained from multiple references. Two versions of the instrument in two different labs were used to collect data over a period of 3 years and inter-laboratory and inter-instrument variations are discussed. Twenty-four point aqueous and mixed cosolvent buffer systems were employed to improve the accuracy of pK(a) measurements. It has been demonstrated that the method allows direct pK(a) measurements in aqueous buffers for many compounds of low solubility, often unattainable by other methods. The pK(a) measurements of compounds with extremely low solubility using multiplexed CE with methanol/water cosolvent buffers are presented.

Hydrolysis in pharmaceutical formulations.

This literature review presents hydrolysis of active pharmaceutical ingredients as well as the effects on dosage form stability due to hydrolysis of excipients. Mechanisms and measurement methods are discussed and recommendations for formulation stabilization are listed.

A water soluble benzazepine cholecystokinin-B receptor antagonist

Abstract A series of 5-substituted-3-ureidobenzazepin-2-ones bearing ioizable functionality was synthesized as potential cholecystokinin-B (CCK-B) receptor antagonists. SAR of this series of compounds demonstrated the optimal combination of a carboxylic acid and 5-cyclohexyl group, providing the high affinity (CCK-B IC 50 = 0.10 nM), water soluble CCK-B antagonist 2 .

Identification of photodegradants of droloxifene by combined HPLC‐‐MS, NMR spectroscopy and computational chemistry

A combination of high-performance liquid chromatography (HPLC)–mass spectrometry and 1H and 13C NMR spectroscopy was utilized to characterize the photodecay products of droloxifene, a potent new estrogen receptor agonist. Structurally similar to tamoxifen, droloxifene demonstrates a complex and unique decay scheme, including the formation of two naphthalene derivatives which were unexpected decay products and previously unreported for this class of compound. Elucidation of the decay products was assisted by the use of computational chemistry, namely by correlating simulated UV spectra and aqueous solvation free energies with actual UV spectra and HPLC retention data. In addition to describing the photodecay scheme of droloxifene, the present work demonstrates the utility of computational chemistry in providing support for the identification of unknown compounds. Copyright