Development of machine learning models of ß-cyclodextrin and sulfobutylether-ß-cyclodextrin complexation free energies.

A new set of 142 experimentally determined complexation constants between sulfobutylether-ß-cyclodextrin and diverse organic guest molecules, and 78 observations reported in literature, were used for the development of the QSPR models by the two machine learning regression methods - Cubist and Random Forest. Similar models were built for ß-cyclodextrin using the 233-compound dataset available in the literature. These results demonstrate that the machine learning regression methods can successfully describe the complex formation between organic molecules and ß-cyclodextrin or sulfobutylether-ß-cyclodextrin. In particular, the root mean square errors for the test sets predictions by the best models are low, 1.9 and 2.7kJ/mol, respectively. The developed QSPR models can be used to predict the solubilizing effect of cyclodextrins and to help prioritizing experimental work in drug discovery.

Effect of chitosan glutamate, carbomer 974P, and EDTA on the in vitro Caco-2 permeability and oral pharmacokinetic profile of acyclovir in rats.

BACKGROUND: Chitosan glutamate and polyacrylic acid (e.g., carbomer 974P) are known to modulate the tight junctions in the intestinal wall and increase permeability and blood exposure of drugs absorbed orally by the paracellular route. AIM: To assess the impact of chitosan glutamate and carbomer 974P on the absorption of paracellularly absorbed model drug, acyclovir, in vitro and in rat in vivo. METHODS: The influence of chitosan glutamate and carbomer 974P (alone and in combination with EDTA-Na2) on the in vitro Caco-2 permeability and oral pharmacokinetic profile in the rat of acyclovir was investigated. RESULTS: In the presence of chitosan glutamate, the apparent permeability of acyclovir across Caco2 monolayer increased 4.1 times relative to control. This increase was accompanied by a significant ( approximately 60%) decrease in transepithelial electrical resistance values indicating opening of the tight junctions in the cell monolayer. In rat, chitosan glutamate doubled oral bioavailability of acyclovir and tripled the amount of acyclovir excreted unchanged into urine. In contrast, the effect of carbomer 974P was not statistically significant at 5% level. CONCLUSIONS: In conclusion, chitosan glutamate (1-3%) and chitosan glutamate (1%)/EDTA-Na2 (0.01%) are effective excipients to increase permeability of acyclovir across Caco-2 cell monolayers and the oral absorption in the rat in vivo.

A class of selective antibacterials derived from a protein kinase inhibitor pharmacophore.

As the need for novel antibiotic classes to combat bacterial drug resistance increases, the paucity of leads resulting from target-based antibacterial screening of pharmaceutical compound libraries is of major concern. One explanation for this lack of success is that antibacterial screening efforts have not leveraged the eukaryotic bias resulting from more extensive chemistry efforts targeting eukaryotic gene families such as G protein-coupled receptors and protein kinases. Consistent with a focus on antibacterial target space resembling these eukaryotic targets, we used whole-cell screening to identify a series of antibacterial pyridopyrimidines derived from a protein kinase inhibitor pharmacophore. In bacteria, the pyridopyrimidines target the ATP-binding site of biotin carboxylase (BC), which catalyzes the first enzymatic step of fatty acid biosynthesis. These inhibitors are effective in vitro and in vivo against fastidious gram-negative pathogens including Haemophilus influenzae. Although the BC active site has architectural similarity to those of eukaryotic protein kinases, inhibitor binding to the BC ATP-binding site is distinct from the protein kinase-binding mode, such that the inhibitors are selective for bacterial BC. In summary, we have discovered a promising class of potent antibacterials with a previously undescribed mechanism of action. In consideration of the eukaryotic bias of pharmaceutical libraries, our findings also suggest that pursuit of a novel inhibitor leads for antibacterial targets with active-site structural similarity to known human targets will likely be more fruitful than the traditional focus on unique bacterial target space, particularly when structure-based and computational methodologies are applied to ensure bacterial selectivity.

Design and utilization of the drug-excipient chemical compatibility automated system.

To accelerate clinical formulation development, an excipient compatibility screen should be conducted as early as possible and it must be rapid, robust and resource sparing. This however, does not describe the traditional excipient compatibility testing approach, requiring many tedious and labor intensive manual operations. This study focused on transforming traditional practices into a completely automated screening process to increase sample throughput and realign resources to more urgent areas, while maintaining quality. Using the developed system, a complete on-line performance study was conducted whereby drug-excipient mixtures were weighed, blended and subjected to accelerated stress stability for up to 1 month, followed by sample extraction and HPLC analysis. Compared to off-line traditional study protocols, the system provided similar relative rank order results with equivalent precision and accuracy, while increasing sample throughput. The designed system offers a resource sparing primary screen for drug-excipient chemical compatibility for solid dosage form development. This approach allows risk assessment analysis, based upon formulation complexity, to be conducted prior to the commitment of resources and candidate selection for clinical development.

Development of a semi-automated chemical stability system to analyze solution based formulations in support of discovery candidate selection.

A semi-automated chemical stability system was developed, validated, and implemented to assess the chemical and physical stability (24 h) of intravenous and oral solution based formulations in support of preliminary in vivo drug discovery studies. The system utilizes a single Agilent 1100 LC and Xterra column with multiple UV wavelength monitoring. Mobile phase selection, either basic or acidic, is selected base upon on the physico-chemical properties of the test compound. The system was validated against 14 new chemical entities across multiple therapeutic areas. The results indicated that drug discovery compounds could be accurately quantified (<2% R.S.D.) in a wide range of formulation vehicles in greater than 90% of the test cases. This method can be used as a quantitative tool for triaging formulation variables and packaging configurations to quickly develop stable solutions for dosing.

The road map to oral bioavailability: an industrial perspective.

Optimisation of oral bioavailability is a continuing challenge for the pharmaceutical and biotechnology industries. The number of potential drug candidates requiring in vivo evaluation has significantly increased with the advent of combinatorial chemistry. In addition, drug discovery programmes are increasingly forced into more lipophilic and lower solubility chemical space. To aid in the use of in vitro and in silico tools as well as reduce the number of in vivo studies required, a team-based discussion tool is proposed that provides a 'road map' to guide the selection of profiling assays that should be considered when optimising oral bioavailability. This road map divides the factors that contribute to poor oral bioavailability into two interrelated categories: absorption and metabolism. This road map provides an interface for cross discipline discussions and a systematic approach to the experimentation that drives the drug discovery process towards a common goal - acceptable oral bioavailability using minimal resources in an acceptable time frame.

The effect of bergamottin on diazepam plasma levels and P450 enzymes in beagle dogs.

Bergamottin, a furanocoumarin isolated from grapefruit juice, was investigated for the ability to increase diazepam bioavailability and for its effect on cytochrome P450 (P450) enzymes in the beagle dog liver and intestine. To study the effect of bergamottin on diazepam pharmacokinetics, male beagle dogs were dosed with bergamottin (1 mg/kg) p.o. 0 or 2 h before p.o. diazepam (10 mg). In a second experiment, bergamottin (0.1 mg/kg) was dosed i.v. or p.o. 1 h before p.o. diazepam (10 mg). Plasma samples were collected over 24 h postdose, analyzed by liquid chromatography/mass tandem spectrometry, and diazepam pharmacokinetic parameters were determined. To study the effect of bergamottin on P450 enzymes, beagle dog liver and jejunum was harvested after a 10-day dosing regimen of bergamottin (1 mg/kg) p.o. per day; microsomes were prepared and analyzed for CYP3A12, CYP2B11, CYP1A1/2, and tolbutamide hydroxylase activity. Bergamottin predosing increased the plasma levels of diazepam as observed by C(max) (278.75 ng/ml versus 5.49 ng/ml) and the area under the curve [AUC((0-TLDC))] (247.69 versus 2.79 ng x hr/ml) in bergamottin versus placebo groups, respectively, indicating P450 enzyme inhibition. Diazepam plasma concentrations were increased to a similar level in the presence of i.v. and p.o. administered bergamottin. In hepatic microsomes, bergamottin treatment for 10 days reduced the activity of CYP3A12 by 50% and CYP1A1/2 by 75%. Tolbutamide hydroxylase activity did not change, and CYP2B11 activity was moderately induced. In jejunal microsomes, CYP3A12 activity doubled with bergamottin treatment. CYP2B11, CYP1A1/2 activity and tolbutamide hydroxylation was not detected. In conclusion, bergamottin is both an inhibitor and an inducer of P450 enzymes.