An ion channel library for drug discovery and safety screening on automated platforms.

Ion channels represent the third largest class of targets in drug discovery after G-protein coupled receptors and kinases. In spite of this ranking, ion channels continue to be under exploited as drug targets compared with the other two groups for several reasons. First, with 400 ion channel genes and an even greater number of functional channels due to mixing and matching of individual subunits, a systematic collection of ion channel-expressing cell lines for drug discovery and safety screening has not been available. Second, the lack of high-throughput functional assays for ion channels has limited their use as drug targets. Now that automated electrophysiology has come of age and provided the technology to assay ion channels at medium to high throughput, we have addressed the need for a library of ion channel cell lines by constructing the Ion Channel Panel (ChanTest Corp., Cleveland, OH). From 400 ion channel genes, a collection of 82 of the most relevant human ion channels for drug discovery, safety, and human disease has been assembled.Each channel has been stably overexpressed in human embryonic kidney 293 or Chinese hamster ovary cells. Cell lines have been selected and validated on automated electrophysiology systems to facilitate cost-effective screening for safe and selective compounds at earlier stages in the drug development process. The screening and validation processes as well as the relative advantages of different screening platforms are discussed.

Once daily loratadine versus astemizole once daily.

This study was designed to compare the efficacy and safety of loratadine and astemizole for the treatment of seasonal allergic rhinitis. A total of 167 adult patients with seasonal allergic rhinitis was enrolled in a randomized double-blind, parallel group study. Patients were treated once daily for 2 months during a spring allergy season. Both treatment groups showed significant reduction of symptoms (P < .01) from baseline. The physicians' and patients' evaluations of response to treatment were generally higher for loratadine than astemizole but only reached statistical significance (P < .05) at the 1-week evaluation. Astemizole-treated patients showed statistically significantly more weight gain than did loratadine-treated patients. Loratadine and astemizole were comparable in reducing the signs and symptoms of seasonal allergic rhinitis. Both treatments were well tolerated, although less weight gain was observed in patients treated with loratadine.

Controlled trial of H1 antagonists in the treatment of chronic idiopathic urticaria.

The efficacy of astemizole, diphenhydramine, and hydroxyzine hydrochloride in the treatment of chronic idiopathic urticaria was evaluated in this 3-month double-blind, randomized, parallel group study. Thirty-six adult patients were randomly assigned, 13 to the astemizole group (10 mg daily), 12 to the diphenhydramine group (25 mg t.i.d.), and 11 to the hydroxyzine hydrochloride group (25 mg t.i.d.). Demographic data were statistically similar for all variables assessed in the three treatment groups. Seven (58%) of the diphenhydramine patients withdrew before the end of the study, six because of lack of efficacy and one because of drowsiness. Two (18%) of the hydroxyzine hydrochloride patients withdrew, one because of lack of efficacy and one because of drowsiness. Two patients (15%) in the astemizole group withdrew, one because of adverse reaction, and the other because of lack of efficacy. Mean total symptom scores and mean individual symptom scores were lower in the astemizole group than in the other two groups. Wheal area measurements (0.1 mg/mL histamine challenge) decreased more in the astemizole and hydroxyzine hydrochloride groups than in the diphenhydramie group (P = .02). With regard to symptoms, 12/13 patients in the astemizole group improved clinically during their treatment period, versus 8/11 in the hydroxyzine hydrochloride group and 5/12 in the diphenhydramine group. The mean time to first observed therapeutic effect (maintained for three consecutive days) was 5.5 days in the astemizole group, 10.9 days in the hydroxyzine hydrochloride group, and 7.2 days in the diphenhydramine group. In this study, astemizole was as effective as hydroxyzine in patients treated for chronic idiopathic urticaria.