Pharmacokinetic and Ocular Toxicity Evaluation of Latanoprost Ophthalmic Solution, 0.005%, with Preservative Level Reduced to Below the Limit of Quantitation.

Purpose: The systemic and ocular pharmacokinetics (PK), and ocular toxicity of benzalkonium chloride (BAK)-free TearClear latanoprost ophthalmic solution, 0.005% formulation (TC-002) were evaluated. TC-002 is designed to selectively capture BAK at the time of drug administration; therefore, the dose delivered to the eye contains no quantifiable level of preservative. Methods: The systemic and ocular PK of TC-002 were compared to a BAK containing reference listed drug (RLD, Xalatan™) over a 24-h period, after a single topical ocular dose to 1 eye of male Dutch Belted (DB) rabbits (n = 3/timepoint). Latanoprost acid concentrations were measured in plasma and ocular tissues. The ocular toxicity was evaluated in a separate study and included toxicokinetic evaluation of TC-002 after once daily topical ocular dosing into each eye of DB rabbits (n = 8/group) for at least 28 days. Toxicity endpoints included ophthalmic and clinical evaluations, necropsy, and microscopic evaluation of ocular tissues. Results: Average ratios of Cmax values for TC-002/RLD ranged from 0.6 to 1.6, and Cmax and area under the concentration-time curve of last observed concentration (AUClast) exposures to latanoprost acid were similar (<2-fold) between the 2 treatments. In the 28-day study, the Tmax was achieved in both groups in <0.5 h. There were no abnormal ocular findings. Conclusions: TC-002 with no quantifiable preservative or BAK-containing RLD exhibited similar ocular and systemic PK profiles. TC-002 was well tolerated and comparable to RLD. TC-002 retains the safety and PK characteristics of RLD without the added concern of long-term exposure of the eye to preservatives.

Comparative evaluation of multi-purpose solutions in the stabilization of tear lysozyme.

The range and extent of tear proteins removed by various multi-purpose solutions has been investigated, but there is little information in the literature about their ability to prevent denaturation of tear proteins, particularly lysozyme. The purpose of this study was to determine the ability of Bausch+Lomb Biotrue™ multi-purpose solution and other care solutions to affect denaturation of lysozyme using a lysozyme activity assay. The test solutions used were: Biotrue multi-purpose solution, Bausch+Lomb renu(®) fresh™, formerly ReNu MultiPlus(®), Alcon OPTI-FREE RepleniSH, Alcon OPTI-FREE EXPRESS, CIBA VISION AQuify, and AMO COMPLETE Multi-Purpose Solution Easy Rub Formula. A phosphate-buffered saline (PBS) solution served as a control. The test and control solutions containing lysozyme were exposed to sodium dodecyl sulfate (SDS), a known denaturant of the enzyme. The assay was based on digestion of the cell wall of Micrococcus luteus in a suspension, a substrate sensitive to active lysozyme. Enzymatic activity against M. luteus was used to assess activity of lysozyme. The decrease in the turbidity of the cell wall suspension, a measure of relative enzyme activity, was determined by following the decrease in absorbance (at 450nm) over time using a spectrophotometer. Statistically significant greater stabilization of lysozyme was observed with Biotrue multi-purpose solution and renu fresh than with OPTI-FREE RepleniSH, OPTI-FREE EXPRESS, AQuify, COMPLETE Multi-Purpose Solution Easy Rub Formula, and a PBS control. The lysozyme activity assay revealed that Biotrue multi-purpose solution and renu fresh have the ability to stabilize lysozyme under conditions that typically denature the protein.

Miniature device for aqueous and non-aqueous solubility measurements during drug discovery.

PURPOSE: A miniature device was developed for the measurement of aqueous and non-aqueous equilibrium solubility during drug discovery. The solubility values obtained using the miniature device were compared to those obtained using the conventional shake-flask method. METHODS: The aqueous solubility of six structurally diverse compounds, the solubility of carbamazepine in various cosolvent systems, and the pH-solubility profile of saquinavir were determined using the miniature device. The device contains a multichannel cartridge pump and a Tygon tubing that is mounted on the pump with two ends linked by a syringe filter. The drug slurry was filled into the tubing and circulated inside, continually passing through the syringe filter. At the end of the experiment, the filtrate was collected and analyzed directly by High-Pressure Liquid Chromatography (HPLC). The solubility was also determined by the shake-flask method. RESULTS: The solubility values determined by the miniature device were in good agreement with those measured by the conventional shake-flask method. CONCLUSIONS: The miniature device provides a unique way of testing aqueous and non-aqueous equilibrium solubility in a microscale setting. With approximately 1 mg of compound, it is possible to determine the entire pH-solubility profile. The device is useful for solubility screening during lead optimization and candidate selection in early drug discovery, when compound supply is limited. It can also be used for screening solubility in non-aqueous systems to select vehicles for preclinical in vivo studies.

A quantitative structure-property relationship for predicting drug solubility in PEG 400/water cosolvent systems.

PURPOSE: A quantitative structure-property relationship (QSPR) was developed to predict drug solubility in binary mixtures of polyethylene glycol (PEG) 400 and water. The ability of the QSPR model to predict solubility was assessed and compared to the classic log-linear cosolvency model. METHODS: The solubility of 122 drugs, ranging in log P from -2.4 to 7.5, was determined in 0%, 25%, 50%, and 75% PEG (v/v in water) by the shake-flask method. Solubility data from 84 drugs were fit by linear regression using the following molecular descriptors: molecular weight, volume, radius of gyration, density, number of rotatable bonds, hydrogen-bond donors, and hydrogen-bond acceptors. The multiple linear regression model was optimized by a genetic algorithm guided selection method. The remaining 38 compounds were used to test the predictability of the model. RESULTS: QSPR-based models developed at each volume fraction with the training set compounds showed a reasonable correlation coefficient (r) of approximately 0.9 and a root mean square (rms) error of <0.5 log unit. The model predicted solubility values of approximately 78% of the testing set compounds within 1 log unit. The log-linear model was as effective as the QSPR-based model in predicting the testing set solubilities; however, many drugs, as expected, showed significant deviation from log-linearity. CONCLUSIONS: The QSPR model requires only the chemical structure of the drug and has utility for guiding vehicle identification for early preclinical in vivo studies, especially when compound availability is limited and experimental data such as aqueous solubility and melting point are unknown. When experimental data are available, the log-linear model was verified to be a useful predictive tool.

Phosphonooxymethyl prodrugs of the broad spectrum antifungal azole, ravuconazole: synthesis and biological properties.

Synthesis of phosphonooxymethyl derivatives of ravuconazole, 2 (BMS-379224) and 3 (BMS-315801) and their biological evaluation as potential water-soluble prodrugs of ravuconazole are described. The phosphonooxymethyl ether analogue 2 (BMS-379224) and N-phosphonooxymethyl triazolium salt 3 (BMS-315801) were both prepared from ravuconazole (1) and bis-tert-butyl chloromethylphosphate, but under two different conditions. Both derivatives were highly soluble in water and converted to the parent in alkaline phosphatase, and also in vivo (rat). However, BMS-315801 was found to be less stable than BMS-379224 in water at neutral pH. BMS-379224 (2) has proved to be one of the most promising prodrugs of ravuconazole that we tested, and it is currently in clinical evaluation as an intravenous formulation of the broad spectrum antifungal azole, ravuconazole.

Prediction of aqueous solubility of organic compounds using a quantitative structure-property relationship.

A quantitative structure-property relationship (QSPR) was developed for predicting the aqueous solubility of drug-like compounds from their chemical structures. A set of 321 structurally diverse drugs or related compounds, with their intrinsic aqueous solubility collected from literature, was used in this analysis. The data were divided into a training set (n = 267) for building the model and a randomly chosen testing set (n = 54) for assessing the predictive ability of the model. A series of molecular descriptors was calculated directly from chemical structures and a set of eight descriptors, including dipole moment, surface area, volume, molecular weight, number of rotatable bonds/total bonds, number of hydrogen-bond acceptors, number of hydrogen-bond donors and density, was chosen for the final model. The eight-descriptor model generated by multiple linear regression was further optimized by a genetic algorithm guided selection method. The model has a correlation coefficient (r) of 0.95 and a root-mean-square (rms) error of 0.56 log unit. It predicts the solubility of testing set compounds with a reasonable degree of accuracy (r = 0.84 and rms = 0.86 log unit). The present model can serve as a tool for medicinal chemists to guide their early synthetic efforts in arriving at appropriate analogs.