Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

P–193 First cleavage division perpendicular to the pronuclear axis adversely affects the clinical outcome in human embryos

Study question

Does the direction of formation for the first cleavage plane relative to the pronuclear axis affect clinical outcome?

Summary answer

A first cleavage division perpendicular to the pronuclear axis adversely affects the rate of embryo utilization for transfer or cryopreservation and the pregnancy outcome.

What is known already

It remains unclear how the first cleavage plane is determined in human embryos. By using time-lapse monitoring, our previous study (presented in ESHRE 2019) suggested that both the axis and locations of male and female pronuclei are involved in determining the first embryonic cleavage plane. Furthermore, by using immunofluorescence analysis, it was also revealed that most analyzed zygotes showed two pericentrin signals aligned around the interface between the male and female pronuclei. Our findings suggest that the pronuclear axis strongly influences the positions of the centrosomes, which become mitotic spindle poles and define the first cleavage plane. Study design, size, duration: From January 2015 to December 2017, time-lapse imaging (EmbryoScope®) of 3397 intracytoplasmic sperm injection (ICSI) oocytes was conducted. Of those, the relationship between the pronuclear axis and the first cleavage plane was analyzed in 607 normally fertilized embryos that cleaved to two cells and were obtained in 2015. Furthermore, of 3397 ICSI oocytes, 749 transferred embryos were classified based on the first cleavage patterns relative to the pronuclear axis, and the pregnancy rate was examined.

Participants/materials, setting, methods

A straight line connecting the centers of the pronuclei was defined as the 2PN axis. Based on the direction of the first cleavage relative to the 2PN axis, embryos were classified into three groups: parallel, perpendicular and intermediate. Fresh embryos were transferred on Day 2/3 (fresh-ET). Frozen and thawed embryos were transferred on Day 2/3 or Day 5 (F/T-ET). Clinical pregnancy was defined as confirmed gestational sac in the uterine cavity.

Main results and the role of chance

Of 607 analyzed embryos, 506 produced suitable images and were assigned to one of three groups: parallel (84.4%, n = 427), perpendicular (9.7%, n = 49) and intermediate (5.9%, n = 30). Embryos that formed a cleavage furrow parallel to the 2PN axis were significantly more frequent than others (perpendicular, intermediate) (P &lt; 0.001). The embryo utilization rate for transfer or cryopreservation was significantly lower in the perpendicular group than in the parallel group (30.7% vs. 69.3%, P &lt; 0.01). Furthermore, of 749 transferred embryos, 504 assigned to the parallel and perpendicular groups were selected (n = 470 and n = 34, respectively), and the pregnancy outcome was analyzed. The mean maternal age was not significantly different between groups. The pregnancy rate of embryos was 24.2% (n = 45/186) from fresh-ET and 39.4% (n = 112/284) from F/T-ET in the parallel group, and 0% (n = 0/14) from fresh-ET and 15.0% (n = 3/20) from F/T-ET in the perpendicular group. Regardless of the types of embryo transfer (fresh or F/T), the pregnancy rate was significantly lower in the perpendicular group than in the parallel group (P &lt; 0.01). In addition, one of three patients who became pregnant from the transfer of an embryo in the perpendicular group had a miscarriage.

Limitations, reasons for caution

Since only ICSI embryos were analyzed in this study, the influence of fertilization methods on subsequent development could not be investigated. Further studies including preimplantation genetic testing for aneuploidy may help determine the reasons why pregnancy rates differ between groups.

Wider implications of the findings: We suggest that the 2PN axis is essential for determining the first cleavage plane because it seems to be involved in positioning the mitotic spindle poles. The direction of the first cleavage plane relative to the 2PN axis can be an important indicator for predicting embryo development and pregnancy outcome

Trial registration number

none

P–215 The degree of perivitelline space (PS) at the pronuclear stage affects subsequent embryonic development in human zygotes

Study question

Was embryonic development affected by the degree of perivitelline space (PS) at the pronuclear stage in human zygotes?

Summary answer

Zygotes with a fully surrounding PS showed less cytoplasmic fragmentation and a higher blastocyst development rate (BDR) than zygotes with a partially surrounding PS.

What is known already

We previously used abnormally-fertilized oocytes (zygotes with three pronuclei; 3PN), donated by ART patients in our clinic who gave written consent for the research. The zona pellucida (ZP) was artificially removed from these oocytes at the pronuclear stage, termed ZP-free culture. The resultant ZP-free 3PN embryos showed less cytoplasmic fragmentation and a higher rate of good-quality embryos (GQE) compared with ZP-intact embryos. Furthermore, in our clinical setting, the rate of GQE and BDR of normally-fertilized embryos were clearly improved by ZP-free culture in patients with recurrent failure of ART treatments due to severe cytoplasmic fragmentation at the early cleavage stage.

Study design, size, duration

This study included 49 patients who gave written informed consent for our study and were treated with ART in our clinic between March and December 2020. Embryonic development was compared between zygotes with a fully surrounding PS [PS(+)] with those with a partially surrounding PS [PS(-)] at the pronuclear stage. Furthermore, the ZP of PS(-) embryos were artificially removed at the pronuclear stage, and the rate of GQE and BDR were compared with ZP-intact embryos.

Participants/materials, setting, methods

The degree of PS in 128 zygotes was confirmed by hypertonic preparation using 0.125M sucrose-containing HEPES medium. PS(+) and PS(-) embryos were both cultured as ZP-intact, and the rate of GQE was compared. Furthermore, 223 zygotes were divided into three groups: 1) PS(-)/ZP-intact, 2) PS(-)/ZP-free, and 3) PS(+)/ZP-intact, and cultured in an incubator equipped with time-lapse monitoring up to Day 7, and the rate of GQE, BDR and useable embryos were compared between each groups.

Main results and the role of chance

The degree of PS was confirmed by a hypertonic preparation (shrinkage of the ooplasm) in 128 normally-fertilized zygotes obtained from 44 cases. There were 86 PS(-) (67.2%) and 42 PS(+) (32.8%) zygotes. The mean maternal age was 35.9 in PS(-) and 40.5 in PS(+) (P &lt; 0.01), and the rate of GQE was significantly higher in PS(+) [64.3% (27/42)] than in PS(-)[38.4% (33/86)] (P &lt; 0.01). In addition, of 223 normally-fertilized zygotes obtained from 41 cases, there were 51 PS(-)/ZP-intact (Group 1), 132 PS(-)/ZP-free (Group 2) and 40 PS(+)/ZP-intact (Group 3) zygotes. The rate of GQE was significantly lower in Group 1 [29.4% (15/51)] compared with Group 2 [59.8% (79/132)] and Group 3 [62.5% (25/40)] (P &lt; 0.01). BDR was also significantly lower in Group 1 [51.3% (10/39)] compared with Group 2 [75.0% (99/132)] and Group 3 [65.0% (13/20) (P &lt; 0.01).

Limitations, reasons for caution

Although the artificial removal of ZP at the pronuclear stage (ZP-free culture) clearly increased the rate of GQE, embryonic development was not improved in all cases. It seems that this procedure is only effective in embryos with a viable ooplasm.

Wider implications of the findings: The degree of PS at the pronuclear stage affects subsequent embryonic development in human zygotes. The artificial removal of ZP at the pronuclear stage (ZP-free culture) helps to suppress fragmentation and leads to an increase in GQE and BDR, and eventually, improves pregnancy rate in cases with severe fragmentation.

Trial registration number

non

P–216 Successful pregnancies and deliveries in patients with a recurrent failure of ART treatments following artificial removal of the zona pellucida (ZP) at the pronuclear stage

Study question

Can a novel embryo culture method that artificially removes the ZP at the pronuclear stage yield successful pregnancy in patients with poor-quality embryos and/or blastocysts?

Summary answer

A blastocyst transfer after ZP-free culture can result in pregnancy for patients who cannot obtain good quality blastocysts from conventional culture methods.

What is known already

Perivitelline threads are been associated with the formation of cytoplasmic fragments. We had previously observed perivitelline threads in the adhesive region between the ooplasm and the ZP at the first cleavage in human embryos. We removed the ZP at the pronuclear stage in 71 abnormally fertilized oocytes (zygotes with three pronuclei), donated after conventional IVF (c-IVF), and termed them ZP-free 3PN. We found ZP-free 3PN embryos could be cultured without losing blastomere adhesions. Furthermore, the rate of good quality embryos was significantly higher in ZP-free 3PN embryos compared with ZP-intact embryos (ZP-intact 2PN/2PB and 3PN embryos; P &lt; 0.05).

Study design, size, duration

This study was conducted in two cases selected among patients who underwent ART treatment in our clinic between 2018 and 2019. Cases were selected if they lacked good quality blastocysts in previous c-IVF/Intracytoplasmic Sperm Injection (ICSI) cycles due to massive cytoplasmic fragmentation at the first and second cleavage. We performed a clinical trial of ZP-free culture from December 2019 to March 2020.

Participants/materials, setting, methods

Two cases were selected for this trial. Normally fertilized oocytes were grouped as ZP-free or ZP-intact. For the ZP-free group, 2PN embryos were placed in 0.125M sucrose-containing HEPES to reduce ooplasm size, then ooplasms were completely separated from ZPs by a laser and pipetting. ZP-free and ZP-intact embryos were cultured with time-lapse imaging for up to seven days. Resultant blastocysts were either transferred into uterus or cryopreserved on Day5/6/7 for future embryo transfer cycles.

Main results and the role of chance

The ZP-free culture method was applied to two patients (patient A and B) with recurrent failure of ART in our clinic due to poor-quality embryos and/or difficulties in obtaining good quality blastocysts. In both cases, blastocysts were successfully obtained and cryopreserved for all ZP-free culture cycles. In patient A, one good quality ZP-free blastocyst was freshly transferred five days after oocyte retrieval, and a live male baby (2925g) was delivered at 40 weeks of gestation by caesarean section). In patient B, a frozen/thawed ZP-free blastocyst transfer was conducted, and a live female baby (3225g) was delivered at 39 weeks of gestation by vaginal delivery. This shows ZP-free culturing may help obtain viable embryos in patients for which conventional in vitro culturing methods result in embryos characterized with severe cytoplasmic fragmentation and poor quality in the early cleavage stage.

Limitations, reasons for caution

Although successful pregnancies and deliveries were confirmed in two cases, postnatal evaluations will be absolutely necessary for infants derived from ZP-free culture. In addition, the number of trial cases needs to be expanded, however careful selection of suitable patients is necessary for this novel culture method.

Wider implications of the findings: We found removing the ZP at the pronuclear stage improved embryo development and led to successful pregnancies and deliveries after blastocyst transfer. This indicates ZP-free culturing may be an effective method for decreasing cytoplasmic fragmentation caused by perivitelline threads or adhesion between the ooplasm and the zona pellucida.

Trial registration number

Not applicable

Clinical Outcomes of Post-exposure Prophylaxis following Occupational Exposure to Human Immunodeficiency Virus at Dental Departments of Hiroshima University Hospital

Background

Dental professionals have so many opportunities to use injection needles and sharp instruments during dental treatment that they face an increased risk of needlestick injuries. This retrospective study reports the utilization and clinical outcomes of occupational post-exposure prophylaxis (PEP) with anti-retroviral agents after being potentially exposed to HIV at the dental departments of Hiroshima University Hospital.

Objective

This study reports the utilization and clinical outcomes of occupational post-exposure prophylaxis (PEP) with antiretroviral agents after being potentially exposed to HIV at dental departments of Hiroshima University Hospital.

Methods

Data on the clinical status of HIV-infected source patients and information on HIV-exposed dental professionals from 2007 to 2018 were collected.

Results

Five dentists with an average experience of 5.6 years (1-15 years) were exposed. The averaged CD4-positive cell number and HIV-RNA load were 1176 (768-1898) /μl and less than 20 copies/ml, respectively, in all the patients. Two of the five HIV exposed dentists received PEP. Three months after the exposures, all of their results were negative in HIV antibody/antigen tests.

Conclusion

These data might support the concept of “undetectable equals untransmittable”, although HIV exposure in this study was not through sexual transmission.

Oral environment and taste function of Japanese HIV-infected patients treated with antiretroviral therapy

The aim of the study was to evaluate the oral environment and the taste function of Japanese HIV-infected patients treated with antiretroviral therapy. Their median age of 73 patients taking anti-HIV drugs was 46 years. The median period of taking anti-HIV drugs was 30 months. The oral condition was evaluated by measurement of oral moisture, amount of saliva secretion, the number of oral bacteria, presence of oral candida, a taste test, and the number of missing teeth. The levels of oral moisture and secreted saliva were significantly lower in the HIV-infected group than in the healthy volunteer (control) group. The HIV-infected group showed a more robust decrease in taste sensation than the control group. The number of missing teeth was significantly higher in the HIV-infected group than in the control group. Furthermore, all of the evaluated oral conditions were worse in the HIV-infected patients whose CD4+ T lymphocyte counts were less than 500/mm³ than in the control group. It became clear that the patients taking anti-HIV drugs, especially the CD4+ count < 500/mm3 group, had a deteriorated oral environment and dysgeusia, suggesting that the management of oral hygiene is necessary to maintain oral health, which leads to systemic health.

Application of computer-assisted sperm analysis system to elucidate lack of effects of cyclophosphamide on rat epididymal sperm motion

A computer-assisted sperm analysis (CASA) system was used to examine the motion of epididymal spermatozoa derived from cyclophosphamide (CP)-treated male rats. Male rats were orally dosed daily for 1 week with 20 mg/kg of CP. Males were euthanized or were mated 3 times with untreated females at 1 day, 3 weeks, and 8 weeks after the final treatment. Significant decreases in testicular and epididymal weights and epididymal sperm counts of the treated animals were noted after 8-week recovery. Histopathological morphometry of the testis revealed minimal damage to spermatogonia at 1 day after the final treatment and to spermatocytes after 3-week recovery in the CP-treated group. On Caesarian section, increased post-implantation losses were found in females mated with CP-treated males in matings starting 1 day and 3 weeks after the final treatment. On the other hand, none of the sperm motion parameters of treated males derived from the CASA system exhibited significant changes at any time points, although the spermatozoa of treated males at 1 day and 3 weeks after the final treatment were damaged at the DNA level, and the spermatozoa of males after 8-week recovery had been the target cells of CP when they were spermatogonia in the testis. It was thus found that damaged spermatozoa could exhibit no changes on their motion when the damage was confined to the nuclei, and that the effect of CP on sperm nuclei was reversible.

Validation study of assay method for DX-8951 and its metabolite in human plasma and urine by high-performance liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry

A new liquid chromatographic/mass spectrometric assay has been developed for the determination of DX-8951, a new anti-tumor drug, and its 4-hydroxymethyl metabolite (UM-1) in human plasma and urine. Solid-phase extractions were used for sample preparation. A gradient reverse-phase HPLC separation was developed with mobile phases consisting of trifluoroacetic acid and methanol. The detection was conducted using atmospheric pressure chemical ionization tandem mass spectrometry in the selected reaction monitoring mode. A structural analog, camptothecin (CPT), was used as the internal standard. The assay was validated for the determination of DX-8951 and UM-1 in human plasma and urine. The lower limits of quantitation of DX-8951 and UM-1 were 0.1 ng/mL in plasma and 1 ng/mL in urine. The method showed a satisfactory sensitivity, precision, accuracy, recovery and selectivity.

High-Performance liquid chromatographic analysis of lactone and hydroxy acid of new antitumor drug, DX-8951 (exatecan), in mouse plasma

A sensitive high-performance liquid chromatographic (HPLC) method has been developed and validated for the determination of lactone and total drug (lactone plus hydroxy-acid) of DX-8951 in mouse plasma. Solid-phase extraction by C18 cartridge separated lactone from total drug of DX-8951. Analysis was performed using a reverse-phase ODS column with a mobile phase consisting of acetonitrile/0.05 M potassium dihydrogen phosphate (pH 3) (18: 82, v/v) at a flow rate of 1 ml/min. The limits of quantitation of lactone and total drug were 3 ng/ml in plasma and a linear range of determination were observed over the concentration of 3 to 500 ng/ml. This method was applied to pharmacokinetic study in male mice treated with a single intravenous administration of either lactone or hydroxy-acid of DX-8951. The plasma concentrations of lactone from 2 to 6 h after dosing were similar regardless of the form of DX-8951 administered.

Comparisons of the pharmacokinetics and the leukopenia and thrombocytopenia grade after administration of irinotecan and 5-fluorouracil in combination to rats

BACKGROUND

Irinotecan (CPT-11) has been used recently for the treatment of several cancers in combination with 5-fluorouracil (5-FU). Preliminary data on this combination therapy in humans demonstrated no drug interactions between CPT-11 (or its metabolite, SN-38) and 5-FU however, because there is so little information on the combination, the possibility for an interaction still exists.

MATERIAL AND METHODS

CPT-11 and 5-FU were injected intravenously into rats and the pharmacokinetics of CPT-11 and SN-38 and alternations in blood cell count were investigated.

RESULTS

In the group of rats administered 5-FU prior to CPT-11, the area under the concentration-time curve (AUC) of CPT-11 was approximately eight-fold larger compared with the group administered CPT-11 prior to 5-FU. On the other hand, the grade of leukocytopenia or thrombocytopenia was not significantly different among the two groups.

CONCLUSION

In rats, the conversion of CPT-11 into SN-38 is possibly delayed by prior administration of 5-FU.

Sensitive high-performance liquid chromatographic method for the determination of the lactone form and the lactone plus hydroxy-acid forms of the new camptothecin derivative DX-8951 in human plasma using fluorescence detection

A sensitive quantitation of the lactone form and the lactone plus hydroxy-acid forms of DX-8951, a camptothecin derivative, in human plasma has been investigated by high-performance liquid chromatography (HPLC). This assay method consisted of two analytical procedures. In Procedure I, the lactone form was collected by the stepwise separation on a C18 cartridge. In Procedure II, the lactone plus hydroxy-acid forms were collected using another batch of the plasma sample by co-elution of the two forms from a C18 cartridge with acidic solution. The hydroxy-acid form of DX-8951 was quantitated from the difference of the lactone plus hydroxy-acid forms and the lactone form. Thereafter, these pre-treated samples were assayed by HPLC under the same HPLC conditions with a spectrofluorometer and a reverse-phase ODS column. The mobile phase was acetonitrile/0.05 M potassium dihydrogen phosphate (pH 3) (18:82, v/v) at a flow-rate of 1.0 ml/min. For the assay of the lactone form and the lactone plus hydroxy-acid forms of DX-8951 in plasma, analytical method were validated over the range 0.2-50 ng/ml.

Identification of major biliary and urinary metabolites of ecabapide in rats

1. The structures of major biliary and urinary metabolites of ecabapide in rat were identified by comparison with authentic standards using lc-ms and 1H-nmr spectrometry. 2. A major metabolite was found in the bile obtained from rat after an oral dose of 14C-ecabapide and identified as the amidaldehyde derivative. In the urine, two polar metabolites were characterized as the phenolic sulphates. Further, two lipophilic metabolites were identified as alcohol derivatives, and two others as oxamic acids. 3. From these results, it was estimated that the first step in the metabolism of ecabapide in rat was oxidative N-dealkylation to produce the amidaldehyde. This amidaldehyde was further metabolized by two routes, one by reduction of the amidaldehyde into the corresponding alcohol followed by mono-demethylation and subsequent aromatic O-sulphation, the second by oxidation of the amidaldehyde into the oxamic acid followed by mono-demethylation and subsequent aromatic O-sulphation.

Radioimmunoassay method for DX-9065a, an anticoagulant agent. Development, evaluation and application to human plasma

A simple and sensitive radioimmunoassay (RIA) method was developed for determination of DX-9065a, (+)-(2S)-2[4-[[(3S)-1-acetimidoyl-3-pyrrolidinyl] oxy]phenyl]-3-[7-amidino-2-naphthyl]propanoic acid hydrochloride pentahydrate, a newly synthesized anticoagulant agent. Immunogens were prepared by condensation of a hapten with bovine serum albumin via a carboxyl group. Antisera was obtained by immunization of five rabbits with immunogen. High-titer antisera was obtained from 2 rabbits immunized with immunogen. The sensitivity of this newly developed RIA method was 100-fold greater than that of a previously used conventional HPLC method. This method was validated for determination of human plasma samples in clinical trials. The cross-reactivities of employed antisera with three steroisomers (2R3R-, 2R3S- and 2S3R forms) were 0.7, 20.2 and 43.9% respectively. The effect of cross-reactivity of postulated stereoisomers in clinical samples was evaluated by a parallelism study using human plasma samples obtained after oral administration of the drug to healthy Japanese volunteers. Results showed no effect on measured concentration. From these data, this method showed suitable accuracy and precision for the pharmacokinetic evaluation of DX-9065a in clinical study. The method was applied to plasma samples obtained from a healthy Japanese volunteer who had orally received 12.85 mg (10 mg as DX-9065) of the drug. The maximum plasma concentration measured was 6.2 ng ml-1 1 h after administration.

Collaborative assessment of optimal administration period and parameters to detect effects on male fertility in the rat: effects of cyclophosphamide on the male reproductive system

As part of a collaborative project to determine optimal administration period and parameters to detect compound effects on male fertility in the rat, adult male rats were administered cyclophosphamide daily at 5, 10, 20 and 40 mg/kg for 2 weeks, or at 2.5, 5 and 10 mg/kg for 4 or 9 weeks. After the pre-pairing administration period, each male was paired with an untreated female. After mating, testes and epididymides were removed and examined for organ weights, sperm head counts, sperm morphology and histopathology. Mated females were caesarean-sectioned on Day 13 of gestation. Although atrophy of epithelia in the cauda epididymides and decreases of spermatogenic cells in the testes were observed in the higher dose groups in the 2w study, no other effects on the male reproductive system were noted in any of the studies. There were clear effects on pregnancy outcome; implantation efficiency was decreased in the highest dosage groups and postimplantation losses increased in all the dosage groups in all studies. These results suggest that a fertility study with females is needed particularly in the case of mutagenic agents, together with a detailed histopathological evaluation for reliable detection of toxicity on the male reproductive system.

Biliary metabolites of semotiadil fumarate in the rat

After oral administration of 14C-semotiadil fumarate to rat, 81.3% of the dosed radioactivity was excreted into the bile. Five major biliary metabolites were detected and characterized as phenolic O-glucuronides by FAB mass spectrometry and 1H-nmr spectrometry. From these results it was concluded that the first step in the metabolism of semotiadil in rat was oxidations at various portions around the molecule to produce phenols. These oxidations implied the ring-opening of the methylenedioxy ring, O-demethylation of the methoxybenzene, hydroxylation of the ring, and aromatic N-demethylation. The next step was O-glucuronidation of the resulting intermediate phenolic metabolites.

Radioimmunoassay for DS-4574, an antiallergic agent: development, evaluation, and application to human plasma samples

A sensitive radioimmunoassay (RIA) method for DS-4574, an antiallergic drug, in plasma has been developed. As the three major metabolites have a hydroxyl group on the cyclohexyl ring, the triazole ring in the terminal part of molecule was attached to ovalbumin with a spacer of beta-chloropropionic acid succinimido ester to prepare an immunogen. Anti-DS-4574 antisera was obtained in rabbits immunized with the immunogen emulsified in Freund's complete adjuvant. The detection limit of the present RIA method was 1 mg/mL of plasma, which was 100-fold more sensitive than the HPLC method developed previously. Cross-reactivities with three major metabolites were less than 3%. The precision of the assay based on triplicate samples showed intra- and inter-assay coefficients of variations of less than 5% and 4%, respectively. This RIA method was applied to plasma samples of six volunteers who had received a single oral 10 mg dose of DS-4574. Plasma concentrations increased rapidly and reached 60 ng/mL at 0.5 h after administration. The concentration decreased to near the detection limit at 4 h postdose. The present RIA method was shown to possess adequate sensitivity to evaluate pharmacokinetic properties of the drug for clinical study, which was not possible by the HPLC method.

Kinetic characteristics of UDP-glucuronosyltransferases towards a dithiol metabolite of malotilate in hepatic microsomes of rats and rabbits

1. The kinetic activity of UDP-glucuronosyltransferases (UDPGT) towards a dithiol metabolite of malotilate, 2,2-di(isopropoxycarbonyl)ethylene-1,1-dithiol, was investigated using rat and rabbit hepatic microsomes. The thio-glucuronide formed was analysed by h.p.l.c. The Km values obtained using rat and rabbit UDPGT were 36.3 +/- 3.3 and 443 +/- 43 microM, respectively. The Vmax values were 7.14 +/- 0.61 and 29.2 +/- 6.4 nmol/min per mg (mean +/- SD, n = 3). 2. Phenobarbital, an inducer of the GT2 isoform of UDPGT, increased rat microsomal UDPGT activity towards the dithiol. In inhibitory studies, menthol and borneol (specific substrates for GT2a isoform) competitively inhibited glucuronidation of the dithiol. Thus it was concluded that formation of the thio-glucuronide was catalysed mainly by the GT2a isozyme of UDPGT, which is involved in glucuronidation of monoterpenoid alcohols.

Identification of a dithiol intermediate metabolite of malotilate in rats

1. A chemically unstable dithiol intermediate metabolite of malotilate was identified by g.l.c.-mass spectrometry after conversion of the dithiol to a stable derivative by a cyclization reaction with 1,3-dichloroacetone. The dithiol, namely, 2,2-di(isopropoxycarbonyl)ethylene-1,1-dithiol, was present in rat liver at low concentrations. 2. A study of glucuronidation in vitro indicated that the dithiol was converted to the corresponding thio-glucuronide by rat hepatic microsomal enzymes. 3. It was thus confirmed that metabolism of malotilate proceeds via the dithiol intermediate to form the thio-glucuronide, which is a major metabolic pathway.

Isolation and characterization of a new thio-glucuronide, a biliary metabolite of malotilate in rats

1. The metabolism of malotilate, possessing a 1,3-dithiole ring, was studied in rats. A major biliary metabolite of malotilate was isolated and determined to be a thio-glucuronide of the dithiol formed by ring-opening, namely, 1-mercapto-2,2-di(isopropoxycarbonyl)-ethenyl 1-thio-beta-D-glucosiduronic acid. The structure was elucidated by proton-n.m.r., 13C-n.m.r. and high-resolution mass spectrometry. 2. The thio-glucuronide was completely hydrolysed by beta-glucuronidase. This enzymic reaction was inhibited by saccharo-1,4-lactone.

Identification of the metabolites of a new hypoglycaemic agent, midaglizole, in dogs

1. The metabolism of a new hypoglycaemic agent, midaglizole, was studied. Six major metabolites were isolated from the urine of dogs dosed with 14C-midaglizole. The structures of these metabolites were elucidated by n.m.r., i.r., u.v. and mass spectrometry, and confirmed by comparison with synthesized authentic samples. 2. For midaglizole, oxidation on the imidazoline ring and subsequent ring-opening were the major metabolic pathways in dogs. 3. Two metabolites, namely, the imidazole analogue (M-I) and amidine analogue (M-III), had hypoglycaemic activity.