Systematic Target Screening Revealed That Tif302 Could Be an OffTarget of the Antifungal Terbinafine in Fission Yeast

We used a heterozygous gene deletion library of fission yeasts comprising all essential and non-essential genes for a microarray screening of target genes of the antifungal terbinafine, which inhibits ergosterol synthesis via the erg1 enzyme. We identified 14 heterozygous strains corresponding to 10 non-essential [7 ribosomal-protein (RP) coding genes, spt7, spt20, and elp2] and 4 essential genes (tif302, rpl2501, rpl31, and erg1). Expectedly, their erg1 mRNA and protein levels had decreased compared to the control strain SP286. When we studied the action mechanism of the non-essential target genes using cognate haploid deletion strains, knockout of SAGA-subunit genes caused a down-regulation in erg1 transcription compared to the control strain ED668. However, knockout of RP genes conferred no susceptibility to ergosterol-targeting antifungals. Surprisingly, the RP genes participated in the erg1 transcription as components of repressor complexes as observed in a comparison analysis of the experimental ratio of erg1 mRNA. To understand the action mechanism of the interaction between the drug and the novel essential target genes, we performed isobologram assays with terbinafine and econazole (or cycloheximide). Terbinafine susceptibility of the tif302 heterozygous strain was attributed to both decreased erg1 mRNA levels and inhibition of translation. Moreover, Tif302 was required for efficacy of both terbinafine and cycloheximide. Based on a molecular modeling analysis, terbinafine could directly bind to Tif302 in yeasts, suggesting Tif302 as a potential off-target of terbinafine. In conclusion, this genome-wide screening system can be harnessed for the identification and characterization of target genes under any condition of interest.

Comparison of pharmacokinetic characteristics of sildenafil citrate chewable tablets and film-coated tablets in healthy male subjects

UI14SDF100CW is a chewable tablet of sildenafil citrate, which was developed to improve compliance through convenience of administration. The purpose of this study was to compare the pharmacokinetic (PK) properties of sildenafil citrate chewable tablets (UI14SDF100CW) and conventional sildenafil citrate film-coated tablets (Viagra®, Pfizer). A randomized, open-label, single dose, two-treatment, two-period, two-way crossover study was conducted in 60 healthy male volunteers. In each period, the subjects received a single oral dose of UI14SDF100CW or Viagra® (both tablets contain 140.45 mg of sildenafil citrate, which is equivalent to 100 mg of sildenafil). Serial blood samples were collected up to 24 h post-dose for PK analysis. The plasma concentration of sildenafil was determined using a validated HPLC-MS/MS assay. PK parameters of sildenafil were calculated using non-compartmental methods. The plasma concentration-time profiles of sildenafil in both formulations were similar. For UI14SDF100CW, the C(max) and AUC(last) of sildenafil were 1068.69 ± 458.25 (mean ± standard deviation) mg/L and 3580.59 ± 1680.29 h·mg/L, and the corresponding values for Viagra® were 1146.84 ± 501.70 mg/L and 3406.35 ± 1452.31 h·/L, respectively. The geometric mean ratios (90% confidence intervals) of UI14SDF100CW to Viagra® for C(max) and AUC(last) were 0.933 (0.853–1.021) and 1.034 (0.969–1.108), respectively, which met the bioequivalence criteria of Korean regulatory agency. In conclusion, UI14SDF100CW and Viagra® showed similar PK properties. Therefore, UI14SDF100CW can be an alternative to sildenafil for the treatment of erectile dysfunction, providing better compliance.

Pharmacokinetic characteristics of cilostazol 200 mg controlled-release tablet compared with two cilostazol 100 mg immediate-release tablets (Pletal) after single oral dose in healthy Korean male volunteers

Cilostazol controlled-release (CR) tablets have recently been developed by Korea United Pharm (Seoul, Korea). The tablets use a patented double CR system, which improves drug compliance by allowing "once daily" administration and reduces adverse events by sustaining a more even plasma concentration for 24 h. We conducted an open, randomized, two-period, two-treatment, crossover study to compare the pharmacokinetic (PK) characteristics and tolerability of cilostazol when administered to healthy Korean male volunteers as CR or immediate release (IR) tablets (Pletal, Korea Otsuka Pharmaceutical Co., Gyeonggi-do, Korea). Each volunteer was randomly allocated to receive a single tablet of cilostazol CR (200 mg) or two tablets of cilostazol IR (100 mg) with a 7-day washout period between treatments. Plasma cilostazol, OPC-13015 (3,4-dehydrocilostazol), and OPC-13213 (4'-trans-hydroxycilostazol) were assayed using liquid chromatography-tandem mass spectrometry for PK analysis. Thirty participants completed the study with no clinically relevant safety issues. The peak concentrations (C(max), mean ± SD) of cilostazol CR and cilostazol IR were 1414.6 ± 49.3 and 1413.1 ± 35.2 ng/mL, respectively, and the areas under the plasma concentration-time curve from 0 to the last concentration (AUC(last)) were 23928.7 ± 65.9 and 25312.0 ± 62.6 ng·h/mL, respectively. The geometric mean ratios (cilostazol CR/cilostazol IR, GMR) of the C(max) and AUC(last) values were 1.001 (90% CI: 0.822, 1.220) and 0.945 (90% CI: 0.814, 1.098), respectively. The frequencies of adverse events were similar. The present study showed that cilostazol PK and tolerability were comparable when administered to healthy Korean men, regardless of whether administered as cilostazol CR or IR.

Bioequivalence of Two Erlotinib Formulations in Healthy Volunteers

BACKGROUND: Erlotinib is a tyrosine kinase inhibitor prescribed for the treatment of non-small cell lung cancer and pancreatic cancer. The aim of this study was to compare the safety and pharmacokinetics (PK) of a generic (test) formulation of erlotinib with those of a reference formulation in healthy volunteers. METHODS: A randomized, open-label, single-dose two-treatment, two-period, two-sequence, crossover study was conducted in Clinical Trials Center, Chungnam National University Hospital with 40 healthy men. Subjects orally received either one 150 mg tablet of the test or the corresponding dose of the reference, and crossover phases were separated by 14-day washout. Plasma samples were collected up to 72 hr post-dose. Plasma erlotinib concentrations were determined by liquid chromatography-tandem mass spectrometry. PK parameters were calculated by non-compartmental analysis. The safety was monitored throughout the study. RESULTS: A total of 21 cases of adverse events were reported. They are mild and relieved without an intervention. There was no serious adverse event. Median times to peak concentration of two formulations were 3.0. Means [SD] for peak concentration (Cmax) and area under the plasma concentration-time curve (AUC) of the test were 1,298 [346] microg/L and 25,318 [7,668] hrxmicrog/L. Those of the reference were 1,193 [378] microg/L and 24,853 [8,419] hrxmicrog/L. Geometric mean ratios (90% confidence intervals) for the test to the reference were 1.10 (1.02-1.18) for Cmax and 1.02 (0.97-1.09) for AUC. CONCLUSION: Two formulations were safe and well-tolerated. PK findings suggest that the test formulation is equivalent to the reference in terms of pharmacokinetics.