The use of on-line and off-line chromatographic extraction techniques coupled with mass spectrometry for support of in vivo and in vitro assays in drug discovery

We have investigated various sample chromatographic extraction and sample preparation methods for liquid chromatography mass spectrometry analysis in order to increase the throughput of various in vivo and in vitro assays in support of drug discovery. The results indicated that direct plasma injection, although certainly faster than conventional protein precipitation for sample preparation, had problems associated with column longevity and overall robustness. Frequently a single study could not be completed without column replacement. On-line solid phase extraction, on the other hand, compared well with off-line solid phase extraction, using our LC extraction column design, as contamination of the extraction column was minimized by back flushing using the Gilson syringe pump. Finally, on-line solid phase extraction for support of Caco-2 permeability studies worked very well for both single components and mixtures as the matrix was much simpler, presenting fewer contamination problems.

Design, synthesis and biological evaluation of pyridine-phenylpiperazines: a novel series of potent and selective alpha1a-adrenergic receptor antagonist

Beginning from the screening hit and literature alpha1-adrenergic compounds, a hybridized basic skeleton A was proposed as the pharmacophore for potent and selective alpha1a-AR antagonists. Introduction of a hydroxy group to increase the flexibility afforded B which served as the screening model and resulted in the identification of the second-generation lead 1. Using the Topliss approach, a number of potent and selective alpha1a-AR antagonists were discovered. In all cases, binding affinity and selectivity at the alpha1a-AR of S-hydroxy enantiomers were higher than the R-hydroxy enantiomers. As compared to the des-hydroxy analogues, the S-hydroxy enantiomers displayed comparable potency and better selectivity at alpha1a-AR. The S-hydroxy enantiomer 17 (Ki = 0.79 nM; alpha1b/alpha1a = 800; alpha1d/alpha1a = 104) was slightly less potent but much more selective at alpha1a-AR than tamsulosin (Ki = 0.13 nM, alpha1b/alpha1a = 15, alpha1d/alpha1a = 1.4). Compound 17 displayed higher selectivity in inhibiting rat prostate contraction over rat aorta contraction and also exhibited a higher degree of uroselectivity than tamsulosin in the anesthetized dog model.

Design, synthesis, and structure-activity relationships of phthalimide-phenylpiperazines: a novel series of potent and selective alpha(1)(a)-adrenergic receptor antagonists

Beginning from the screening hit and literature alpha(1)-adrenergic compounds, a hybridized basic skeleton A was proposed as the pharmacophore for potent and selective alpha(1a)-AR antagonists. Introduction of a hydroxy group to increase the flexibility afforded B which served as the screening model and resulted in the identification of the second-generation lead 1. Using the Topliss approach, a number of potent and selective alpha(1a)-AR antagonists were discovered. In all cases, binding affinity and selectivity at the alpha(1a)-AR of S-hydroxy enantiomers were higher than those of the R-hydroxy enantiomers. As compared to the des-hydroxy analogues, the S-hydroxy enantiomers had slightly lower binding affinity at alpha(1a)-AR but gained more than 2-fold selectivity for alpha(1a)-AR over alpha(1b)-AR, and 2- to 6-fold selectivity for alpha(1a)-AR over alpha(1d)-AR. They also had less cross activities against a panel of 25-35 peripheral and CNS receptors. The S-hydroxy enantiomers 23 and 24 (K(i) = 0.29 nM, 0.33 nM; alpha(1b)/alpha(1a) >5690, >6060; alpha(1d)/alpha(1a) = 186, 158, respectively) were slightly less potent but much more selective at alpha(1a)-AR than tamsulosin (K(i) = 0.13 nM, alpha(1b)/alpha(1a) = 14.8, alpha(1d)/alpha(1a) = 1.4). In the functional assay, the S-hydroxy enantiomers 20, 23, and 24 were less potent than tamsulosin in inhibiting contractions of rat prostate tissue but more selective in the inhibition of tissue contractions of rat prostate versus rat aorta. Compound 24 was selected as the development candidate for the treatment of BPH.

Evaluation of the immobilized artificial membrane phosphatidylcholine. Drug discovery column for high-performance liquid chromatographic screening of drug-membrane interactions

Chromatographic retention factors (k') of a series of eight beta-adrenoceptor antagonist compounds (beta-adrenolytic drugs) were determined employing an immobilized artificial membrane column (IAM.PC.DD). The influence of mobile phase pH, ionic strength, and organic modifier composition was studied in order to examine column performance. After the IAM.PC.DD columns were exposed to approximately 7000 column volumes of a 0.01 M PBS mobile phase, five out of six columns tested showed significant peak broadening and decreased k' values indicative of premature column failure. The data suggested that the immobilized phospholipids stationary phase was removed by the 0.01 M PBS mobile phase. The beta-adrenolytic drug's log k'IAM values obtained with an IAM.PC.DD column were compared to an esterIAM.PC.MG column for predicting drug membrane interactions. For the linear regression analysis between log k'IAM and the logarithm of the n-octanol-water partition coefficients (rIAM.PC.DD = 0.8710 vs. rIAM.PC.MG = 0.9538), the C18 HPLC retention factors (rIAM.PC.DD = 0.8408 vs. rIAM.PC.MG = 0.9380), the liposome partition coefficients (rIAM.PC.DD = 0.8887 vs. rIAM.PC.MG = 0.9187), and various pharmacokinetic parameters, significantly better correlations were obtained with the esterIAM.PC.MG column than the IAM.PC.DD column.

Total artificial heart to usher in new age of cardiology

A battery-powered artificial heart--designed to replace the diseased heart both physically and functionally--is completing readiness testing in preparation for human trials. The initial goal is for the artificial heart to last 5 years, at which time a donor heart can be transplanted. No immunosuppression will be needed with the total artificial heart, and the recipient's hospital stay will be much shorter, resulting in a tremendous decreases in cost.

Making the choice: can you go 'latex free'?

Health care facilities have many means available to minimize the risk of latex allergy for both patients and workers. A latex-allergy task force should oversee patient and employee safety. Materials and items that contain latex must be identified, and latex-free alternatives must be found.

Latex allergy: the downside of standard precautions

An increased use of gloves has escalated the incidence of latex sensitivity. Health care workers must be aware of the potential for allergy and limit contact as much as possible. Reactions to natural rubber latex can vary from minor redness to anaphylactic shock.

How do some spell relief? S-u-r-g-e-r-y. Permanent relief for heartburn sufferers

Gastroesophageal reflux disease is common, and curable with surgery. A minimally invasive technique offers patients with heartburn lasting relief. Laparoscopic technique has enhanced heartburn surgery, resulting in minimized pain and recovery time.

Phacoemulsification needle enhances cataract surgery

Phacoemulsification, a cataract removal technique, can be facilitated by certain instruments. A micro-incision needle can help improve surgical team comfort and patient outcomes. Infusional flow helps prevent thermal damage and wound leakage in the eye.