Sitagliptin 100 mg daily effect on DPP-4 inhibition and compound-specific glycemic improvement

OBJECTIVE

In clinical trials, the degree of glucose lowering with sitagliptin has been correlated with the magnitude of dipeptidyl peptidase-4 (DPP-4) inhibition over 24 h. Previous studies evaluating sitagliptin doses ranging from 25 to 200 mg/day demonstrated that the daily dose of 100 mg provided maximal glucose-lowering efficacy for this compound in patients with type 2 diabetes. However, sitagliptin 200 mg once daily provided numerically greater percent plasma DPP-4 inhibition compared with 100 mg once daily. The purpose of this study was to evaluate whether sitagliptin 200 mg once daily provides greater improvement in glycemic efficacy as assessed by weighted mean glucose (WMG) over 24 h relative to sitagliptin 100 mg once daily and to relate the percent DPP-4 inhibition achieved with these doses to any between-treatment differences in glycemic efficacy.

METHODS

In a double-blind crossover study, patients with type 2 diabetes (fasting plasma glucose [FPG] 130-250 mg/dL) were randomized to one of six treatment sequences over three treatment periods (placebo, sitagliptin 100 mg once daily, or sitagliptin 200 mg once daily). Each of the treatment periods was 7 days in duration, with 28-day washout periods between treatments. After each treatment period, patients underwent blood sampling at various time points over 24 h to determine 24-h WMG. Plasma DPP-4 activity was assessed at trough, 24 h following dosing on day 7; percent DPP-4 inhibition was corrected for sample assay dilution.

RESULTS

The 103 randomized patients had a baseline mean FPG of 172 mg/dL. Following a planned interim analysis, the study was stopped because the 24-h WMG values were not different between the sitagliptin doses. Furthermore, a significant carryover effect across periods was observed for FPG; thus, efficacy results from period 1 are presented herein. The 24-h WMG values were significantly (p < 0.01) lower with sitagliptin relative to placebo, but the difference between sitagliptin doses was not significant (p = 0.365). Corrected percent plasma DPP-4 inhibition at trough was not significantly (p = 0.791) different with sitagliptin 200 mg (LS mean [95% CI] 96.9% [90.0, 100.0]) compared with sitagliptin 100 mg (95.6% [88.4, 100.0]). The early termination and the carryover effect described above are limitations to this study.

CONCLUSION

Across sitagliptin doses in this study, the similarity of the 24-h WMG concentrations and the similarity of the corrected DPP-4 inhibition values support prior findings that the maximal glucose-lowering efficacy of sitagliptin is achieved with once-daily dosing of 100 mg. Clinicaltrials.gov: NCT00541229.

Accelerating drug development using biomarkers: a case study with sitagliptin, a novel DPP4 inhibitor for type 2 diabetes

The leveraged use of biomarkers presents an opportunity in understanding target engagement and disease impact while accelerating drug development. For effective integration in drug development, it is essential for biomarkers to aid in the elucidation of mechanisms of action and disease progression. The recent years have witnessed significant progress in biomarker selection, validation, and qualification, while enabling surrogate and clinical endpoint qualification and application. Biomarkers play a central role in target validation for novel mechanisms. They also play a central role in the learning/confirming paradigm, particularly when utilized in concert with pharmacokinetic/pharmacodynamic modeling. Clearly, these attributes make biomarker integration attractive for scientific and regulatory applications to new drug development. In this review, applications of proximal, or target engagement, and distal, or disease-related, biomarkers are highlighted using the example of the recent development of sitagliptin for type 2 diabetes, wherein elucidation of target engagement and disease-related biomarkers significantly accelerated sitagliptin drug development. Importantly, use of biomarkers as tools facilitated design of clinical efficacy trials while streamlining dose focus and optimization, the net impact of which reduced overall cycle time to filing as compared to the industry average.

[Dream in the land of paradoxical sleep]

Paradoxical sleep (PS or REM sleep) is traditionally a matter for neurophysiology, a science of the brain. Dream is associated with neuropsychology and sciences of the mind. The relationships between sleep and dream are better understood in the light of new methodologies in both domains, particularly those of basic neurosciences which elucidate the mechanisms underlying SP and functional imaging techniques. Data from these approaches are placed here in the perspective of rather old clinical observations in human cerebral lesions and in the phylogeny of vertebrates, in order to support a theory of dream. Dreams may be seen as a living marker of a cognitivo-emotional process, called here "eidictic process", involving posterior brain and limbic structures, keeping up during wakefulness, but subjected, at that time, to the leading role of a cognitivo-rational process, called here "thought process". The last one is of instrumental origin in human beings. It involves prefrontal cortices (executive tasks) and frontal/parietal cortices (attention) in the brain. Some clinical implications of the theory are illustrated.

[Preliminary results of a focus-group-based research project on the problems of implementing evidence-based practice in Belgium (Flanders). Do psychiatrists differ from other health care practitioners?]

BACKGROUND

The impact of evidence-based practice (EBP) has increased substantially in recent years. However, health care practitioners are experiencing difficulties in implementing EBP.

AIM

The specific task was to find out what problems are encountered by Flemish (Belgian, Dutch-speaking) health care practitioners. method In order to explore this problem, we adopted a qualitative research strategy and set up 25 focus groups, 5 of which consisted solely of psychiatrists. results Psychiatrists shared with other health care disciplines some concerns about the characteristics of 'evidence' and about the influential role played by their 'partners' in the health care system, namely by government, commercial firms and patients. Psychiatrists perceived their discipline to be much more complex than other disciplines, particularly in areas such as research design, patients' problems, psychiatric diagnosis and therapeutic psychiatrist-patient relationships. The literature and the preliminary results of ongoing research revealed that other disciplines too are confronted with similar complexities.

CONCLUSION

There seems to be no justification for ruling out the possibility of implementing EBP on the basis of discipline-related barriers.

Absolute bioavailability of sitagliptin, an oral dipeptidyl peptidase-4 inhibitor, in healthy volunteers

The purpose of this study was to determine the absolute bioavailability of sitagliptin, an orally active, potent and highly selective dipeptidyl peptidase-4 inhibitor recently approved in the United States for the treatment of type 2 diabetes. The effect of a high fat meal on sitagliptin pharmacokinetics was also assessed. The study was performed in two parts. Intravenous doses (2 h infusion) of 25, 50 and 100 mg were administered double-blind to 10 (8 active, 2 placebo) subjects in a fixed-sequence manner in Part I. In Part II, 12 subjects were randomized to each of three open-label treatments: an intravenous 100 mg dose; a single oral 100 mg final market image tablet administered following a high fat meal and a single oral 100 mg final market image tablet administered fasted. Following each dose, plasma and urine were collected at pre-specified times for evaluation of sitagliptin pharmacokinetics. All doses were generally well tolerated in both parts of the study. Following rising intravenous doses of sitagliptin, AUC(0-infinity) increased dose-proportionally, indicating that plasma clearance is independent of dose over the dose range evaluated. Renal clearance of unchanged sitagliptin accounted for approximately 70% of the total plasma clearance of sitagliptin, indicating that sitagliptin is primarily cleared via renal excretion. Averaged across doses, the mean total plasma clearance was 416 ml/min. The mean absolute bioavailability of sitagliptin was 87% with a 90% CI of (81%, 93%). The AUC(0-infinity) and C(max) geometric mean ratios (fed/fasted) and 90% CIs were 1.03 (0.97, 1.11) and 0.94 (0.86, 1.03), respectively, and were contained within the bounds of (0.80, 1.25). Additionally, the high-fat meal had no significant effect on T(max) or apparent terminal t(1/2). Thus, food does not affect the pharmacokinetics of sitagliptin and therefore can be administered without regard to food.

Effect of a single cyclosporine dose on the single-dose pharmacokinetics of sitagliptin (MK-0431), a dipeptidyl peptidase-4 inhibitor, in healthy male subjects

Sitagliptin (MK-0431) is an orally active, potent, and selective dipeptidyl peptidase-4 inhibitor used for the treatment of patients with type 2 diabetes mellitus. Sitagliptin has been shown to be a substrate for P-glycoprotein in preclinical studies. Cyclosporine was used as a probe P-glycoprotein inhibitor at a high dose to evaluate the potential effect of potent P-glycoprotein inhibition on single-dose sitagliptin pharmacokinetics in healthy male subjects. Eight healthy young men received a single oral 600-mg dose of cyclosporine with a single 100-mg oral sitagliptin dose and a single oral 100-mg sitagliptin dose alone in an open-label, randomized, 2-period, crossover study. Single doses of sitagliptin with or without single doses of cyclosporine were generally well tolerated. The sitagliptin AUC(0-infinity) geometric mean ratio was 1.29 with a 90% confidence interval of (1.24, 1.34). The sitagliptin Cmax geometric mean ratio was 1.68 with a 90% confidence interval of (1.35, 2.08). Cyclosporine coadministration did not appear to affect apparent sitagliptin renal clearance, t(1/2), or C(24 h), suggesting that effects of these high doses of cyclosporine are more likely due to enhanced absorption of sitagliptin, potentially through inhibition of intestinal P-glycoprotein. These results rationalize the use of a single high-dose cyclosporine as a probe inhibitor of P-glycoprotein for compound candidates whose elimination is less dependent on CYP3A4-mediated metabolism.

Safety and tolerability of ertapenem

Ertapenem is a Group 1 carbapenem that was licensed in the USA in November 2001 and in Europe in April 2002. Its safety profile has been assessed in 240 healthy volunteers participating in 12 clinical pharmacology studies and in 2046 patients enrolled in five Phase IIa and eight Phase IIb/III clinical trials. The most common drug-related adverse events (AEs) reported in trials comparing ertapenem and piperacillin-tazobactam and in trials comparing ertapenem and ceftriaxone were: diarrhoea (ertapenem versus piperacillin-tazobactam 5.0% versus 7.0%; ertapenem versus ceftriaxone 5.6% versus 5.9%); infused vein complications (ertapenem versus piperacillin-tazobactam 4.5% versus 7.9%; ertapenem versus ceftriaxone 3.2% versus 4.6%); nausea (ertapenem versus piperacillin-tazobactam 2.5% versus 3.4%; ertapenem versus ceftriaxone 3.4% versus 3.3%); and elevations in alanine aminotransferase levels (ertapenem versus piperacillin-tazobactam 8.8% versus 7.3%; ertapenem versus ceftriaxone 8.3% versus 6.9%). Most ertapenem-related AEs were reported as mild-to-moderate in intensity. Ertapenem was not associated with prolongation of the QTc interval. Local reactions of moderate-to-severe intensity at the infusion site were infrequent and occurred with similar frequency in the ertapenem and comparator treatment groups. No overall differences in safety were observed between elderly (aged > or = 65 years and > or = 75 years) and younger patients. Ertapenem, 1 g once a day given by intravenous infusion or intramuscular injection, was generally well tolerated and had overall safety and tolerability profiles similar to those of piperacillin-tazobactam and ceftriaxone.

Clinical heterogeneity in lymphoedema-distichiasis with FOXC2 truncating mutations

BACKGROUND

Hereditary lymphoedema-distichiasis (LD) is an autosomal dominant disorder that classically presents as lymphoedema of the limbs, with variable age of onset, and extra aberrant growth of eyelashes from the Meibomian gland (distichiasis). Other major reported complications include cardiac defects, cleft palate, and extradural cysts. Photophobia, exotropia, ptosis, congenital ectropion, and congenital cataracts are additional eye findings. Recently, we reported that truncating mutations in the forkhead transcription family member FOXC2 resulted in LD in two families.

METHODS

The clinical findings in seven additional families with LD, including the original family described by Falls and Kertesz, were determined and mutational analyses were performed.

RESULTS

Distichiasis was the most common clinical feature followed by age dependent lymphoedema. There is a wide variation of associated secondary features including tetralogy of Fallot and cleft palate. The mutational analyses identified truncating mutations in all of the families studied (two nonsense, one deletion, three insertion, and one insertion-deletion), which most likely result in haploinsufficiency of FOXC2.

CONCLUSIONS

FOXC2 mutations are highly penetrant with variable expressivity which is not explicable by the pattern of mutations.

Complete removal of nonpalpable breast malignancies with a stereotactic percutaneous vacuum-assisted biopsy instrument

BACKGROUND

Several devices have been developed for sampling nonpalpable mammographic breast lesions. Complete removal of malignancies with a stereotactic percutaneous directional vacuum-assisted biopsy instrument has been reported.

STUDY DESIGN

We reviewed our experience with the percutaneous vacuum-assisted biopsy instrument to identify instances of complete excision of cancers: no residual carcinoma found at surgical excision for malignancies diagnosed by the percutaneous vacuum-assisted biopsy instrument. The radiologic and pathologic characteristics of malignancies completely removed by the percutaneous vacuum-assisted biopsy instrument were compared with those of malignancies with residual carcinoma found at surgical excision.

RESULTS

Fifty-two malignancies were diagnosed by the percutaneous vacuum-assisted biopsy instrument: 16 infiltrating ductal carcinomas, 5 infiltrating lobular carcinomas, and 31 ductal carcinomas in situ. No residual carcinoma was found at surgical excision in 9 (17%) of the 52 malignancies. Patients with complete removal of the malignant lesion were younger than patients with incomplete removal (52 versus 58 years; p = 0.069). Completely removed malignancies were smaller on mammography (4 versus 17 mm; p = 0.213), and more specimens were removed (19 versus 15; p = 0.074). All nine completely removed malignancies presented with calcifications without a mass (p = 0.112), and all nine were ductal carcinoma in situ (p = 0.019).

CONCLUSIONS

Complete removal of nonpalpable breast malignancies is possible with the stereotactic percutaneous directional vacuum-assisted biopsy device. Complete removal is more likely with removal of a large number of specimens from small areas of mammographic calcifications due to ductal carcinoma in situ.

A prospective study of biopsy-confirmed cervical intraepithelial neoplasia grade 1: colposcopic, cytological, and virological risk factors for progression

OBJECTIVES

The objective of this prospective study of histologically confirmed cervical intraepithelial neoplasia (CIN) (including equivocal CIN1) was to determine risk factors for progression to histologically confirmed CIN3, particularly human papillomavirus (HPV) types and cofactors. We postulated that HPV DNA positivity would be a strong, prospective risk factor for progression.

MATERIALS AND METHODS

Possible participants were referred with an abnormal cytological diagnosis of CIN1 or lower-grade disease or external genital warts. Women with histologically confirmed CIN1 (including koilocytotic atypia) or equivocal CIN1 were eligible for follow-up. Of these, 163 women were assessed every 3 months (if a lesion were present) or every 6 months (if a lesion regressed colposcopically during the course of the study), for up to 52 months. Progression was defined histologically, whereas persistence and regression were defined by combined cytological, colposcopic, and histological assessments. Subjects who progressed to a biopsy-confirmed CIN3 or who developed a lesion that was clinically unsafe to follow up (i.e., because of movement into the endocervical canal), were removed from the study and were treated.

RESULTS

A total of 237 patients were evaluated as possible participants. The 74 exclusions at enrollment included 33 patients who had an entry diagnosis of CIN2 to CIN3 or who had lesions that were otherwise already unsafe to follow up, 39 who did not have a lesion on colposcopically directed biopsy, and 2 who were immediately noncompliant. Among the remaining 163 participants, the overall progression rate to histologically confirmed CIN3 was 8%, the persistence rate was 49%, and the regression rate was 43%. All progressions occurred among women who were HPV DNA-positive and had colposcopically immature abnormal transformation zones.

Effects of short- and long-term wheel deprivation on running

The effects of wheel deprivation on running were explored. Eight male rats, well habituated to wheels, were each deprived of wheels for periods of 0, 1, 3, and 10 h during the night (Experiment 1) and 0, 1, 3, and 10 days (Experiment 2). In Experiment 1, as wheel deprivation lengthened, wheel running in the first 24 h of access increased. After 10 days of wheel deprivation subsequent daily running decreased (by 70%), and feeding was suppressed for several days. This temporary decline may be due to detraining and the rats physical inability to run more. Experiment 3 with 12 rats found that the running increase after 3-h wheel deprivation was proportional to the amount of running normally occurring during the deprivation period. Over the short-term, running appears to be regulated like other appetitive behaviors.

[Heparin-induced thrombocytopenia with unfractionated heparin. A prospective study of inpatient treatment of internal medicine patients]

AIM

To investigate the influence of unfractionated heparin on heparin-induced thrombocytopenia (HIT) type II.

PATIENTS AND METHOD

In 162 patients with internal diseases treated therapeutically of prophylactically with unfractionated heparin (heparin sodium, heparin calcium), we carried out a prospective study to determine the incidence of HIT type I and II. 55.6% of the patients were female (n = 90) with an average age of 76.5 years (range: 25 to 96 years) and 44.4% male (n = 72) with an average age of 67.5 years (range: 17 to 93 years). A platelet count was taken regularly before the start of heparin treatment, on the first day of treatment and then every second day from day 5 to 20. Whenever HIT II was suspected, an HIPA test was performed.

RESULT

Type I HIT occurred in 10%, type II in 3% of the cases. Two of the 5 patients with type II developed severe thrombotic complications.

CONCLUSION

In view of the high incidence of HIT, regular platelet counts should always be carried out in patients receiving heparin treatment.

The mouse X-linked developmental mutant, tattered, lies between DXMit55 and Xkh and is associated with hyperkeratinization

The X-linked mouse mutant phenotype, tattered (Td), is associated with prenatal lethality of males and has been mapped previously to the proximal region of the mouse X chromosome. We report here a refined position for Td and demonstrate that it lies in the approximately 0.9-cM interval between DXMit55 and Xkh. This enables us to predict that the human homologue lies either between CLCN5 and the evolutionary breakpoint that lies between GATA1 and PFC or distal to XK and proximal to the evolutionary breakpoint that lies between XK and DMD. Histological analysis of dorsal skin taken from 5-day-old heterozygous animals revealed that the mutation was associated with patches of hyperkeratinzation in the epidermis and in the hair follicles, accompanied by a mild inflammatory infiltrate in the underlying dermis.

Clustering of mutations in the biotin-binding region of holocarboxylase synthetase in biotin-responsive multiple carboxylase deficiency

Holocarboxylase synthetase (HCS) catalyses the biotinylation of the four biotin-dependent carboxylases found in humans. A deficiency in HCS results in biotin-responsive multiple carboxylase deficiency (MCD). We have identified six different point mutations in the HCS gene in nine patients with MCD. Two of the mutations are frequent among the MCD patients analyzed. Four of the mutations cluster in the putative biotin-binding domain as deduced from the corresponding Escherichia coli enzyme and consistent with an explanation for biotin-responsiveness based on altered affinity for biotin. The two others may define an additional domain involved in biotin-binding or biotin-mediated stabilization of the protein.

X-linked myotubular myopathy: clinical observations in ten additional cases

X-linked myotubular myopathy (XLMTM) is a recessively inherited disorder, lethal to males in the first months of life. Since the first report in 1969, at least 90 cases have been described in the literature. Diagnosis is confirmed by muscle biopsy. Linkage studies have localized the disorder to the Xq28 region, close to the loci for X-linked hydrocephalus and MASA syndrome. We report on 10 additional cases of XLMTM from six different families. In addition to classic clinical features of XLMTM, our patients showed interesting associated findings which included birth length > 90th centile and large head circumference with or without hydrocephalus in 70%, narrow, elongated face in 80%, and slender, long digits in 60% of cases. There was concordance in the occurrence and severity of hydrocephalus in most sib pairs. These features in a "floppy" male infant serve as clues for early clinical diagnosis of XLMTM, which can then be confirmed by muscle biopsy. Development of polyhydramnios was observed in the third trimester of an at-risk dizygotic twin gestation monitored by serial sonography with confirmation of XLMTM at birth.

A comparative transcriptional map of a region of 250 kb on the human and mouse X chromosome between the G6PD and the FLN1 genes

The transcriptional organization of the region of the mouse X chromosome between the G6pd and the Fln1 genes was studied in detail, and it was compared with the syntenic region of the human chromosome. A cosmid contig of 250 kb was constructed by screening mouse cosmid libraries with probes for human genes and with whole cosmids. Overlapping cosmids were aligned by comparing EcoRI and rare-cutter restriction enzyme digestions. The gene order and the orientation of transcription were determined by hybridization with fragments from the 5' and 3' moieties of each cDNA. Our work demonstrates that all of the new genes identified in human are present in the mouse. The size of the region, 250 kb, is also very similar, as are gene order and gene organization: the transcriptional organization in "domains" described in human is found to be identical in the mouse. The major difference detected is the much lower content in rare-cutter restriction sites, which is related to the lower G+C and CpG content of mouse DNA. The very high conservation that we have described suggests that a potent selective pressure has contributed to such conservation of gene organization.

X linked myotubular myopathy (MTM1) maps between DXS304 and DXS305, closely linked to the DXS455 VNTR and a new, highly informative microsatellite marker (DXS1684)

The locus for X linked recessive myotubular myopathy (MTM1) has previously been mapped to Xq28 by linkage analysis. We report two new families that show recombination between MTM1 and either DXS304 or DXS52. These families and a third previously described recombinant family were analysed with two highly polymorphic markers in the DXS304-DXS52 interval, the DXS455 VNTR and a newly characterised microsatellite, DXS1684 (82% heterozygosity). These markers did not recombine with MTM1 in the three families. Together with the recent mapping of an interstitial X chromosome deletion in a female patient with moderate signs of myotubular myopathy, our data suggest the following order of loci in Xq28: cen-DXS304-(DXS455, MTM1)-DXS1684-DXS305-DXS52-tel. This considerably refined localisation of the MTM1 locus should facilitate positional cloning of the gene. The availability of highly polymorphic and very closely linked markers will markedly improve carrier and prenatal diagnosis of MTM1.

[Benign testicular and paratesticular tumors]

Five cases of benign testicular and paratesticular tumors are reported which have been treated by conservative methods. A literature review is presented about the most frequent benign testicular and paratesticular neoplasms. The preoperative diagnosis and the choice of treatment are discussed.

Magnetic resonance imaging in schizophrenia: relationship with clinical measures

Relationships were examined between clinical features of schizophrenia and cerebrospinal fluid (CSF) volume in brain obtained by magnetic resonance imaging (MRI) in a sample of 59 patients. The volumes of the cerebral hemispheres and CSF were measured with a computer program designed to separate reliably neural tissue from CSF. The CSF to cranial volume ratios were related to history, symptom profile and outcome functioning. Earlier age of onset was associated with higher sulcal CSF ratio, r = -0.40. The anatomic measures were unrelated to symptom severity. However, patient subtypes differed in the laterality of measures. Higher left hemispheric ratios were seen in patients with severe negative symptoms, and left predominance of ventricular relative to sulcal ratios was associated with the presence of hallucinations and delusions. The results suggest that while higher CSF is related to earlier age of onset, the clinical symptoms are more related to its lateralization. This is consistent with the hypothesis that schizophrenia is a lateralized brain disease.

Biogenesis of synaptic vesicles

The basic endosomal recycling pathway can be modified to generate transcytotic vesicles, storage vesicles and synaptic vesicles. Sorting into synaptic vesicles requires specialized sorting information not present in the transcytotic and storage vesicle proteins. Using mutagenesis we have distinguished the signals for rapid endocytosis and SV targeting in synaptobrevin. Finally, we have evidence that synaptic vesicles can be generated from an endosomal compartment in vitro.