Weight-based versus fixed dose oxytocin infusion for preventing uterine atony during cesarean section in laboring patients: A randomized trial

OBJECTIVE

We compared efficacy of weight-based (0.4 IU/kg/h) versus fixed-dose (34 IU/h) oxytocin infusion during cesarean section.

METHODS

The oxytocin infusion in either group (n = 32 each) was initiated upon cord clamping. Primary outcome measure was adequacy of uterine tone at 4 min after initiating oxytocin infusion. Oxytocin associated side effects were also observed.

RESULTS

Significantly less oxytocin was used with the weight-based versus fixed-dose regimen (16.3 [11.2-22.4] IU vs 20.4 [15.8-26.9] IU; P = 0.036). Incidence of adequate uterine tone was clinically greater but not significantly different with the weight-based versus fixed-dose regimen (81.3% vs 71.9%; P = 0.376). The weight-based regimen was associated with clinically lesser, although not statistically significant need for rescue oxytocin (25% vs 46.9%; P = 0.068) and additional uterotonic (9.4% vs 15.6%; P = 0.708); as well as oxytocin associated side effects (hypotension [34.4% vs 46.9%; P = 0.309], nausea/vomiting [18.8% vs 40.6%; P = 0.055], and ST-T changes [0% vs 3.1%; P = 1.000]).

CONCLUSION

Weight-based oxytocin was not significantly different from the fixed-dose regimen in terms of uterotonic efficacy or associated side-effects, despite significantly lower doses being used. Use of weight-based oxytocin infusion (0.4 IU/kg/h) can be considered in clinical practice.

TRIAL REGISTRATION

Clinical Trial Registry of India (ctri.nic.in, number. CTRI/2021/01/030642).

Guided antipsychotic reduction to reach minimum effective dose (GARMED) in patients with remitted psychosis: a 2-year randomized controlled trial with a naturalistic cohort

BACKGROUND

Patients with remitted psychosis face a dilemma between the wish to discontinue antipsychotics and the risk of relapse. We test if an operationalized guided-dose-reduction algorithm can help reach a lower effective dose without increased risks of relapse.

METHODS

A 2-year open-label randomized prospective comparative cohort trial from Aug 2017 to Sep 2022. Patients with a history of schizophrenia-related psychotic disorders under stable medications and symptoms were eligible, randomized 2:1 into guided dose reduction group (GDR) v. maintenance treatment group (MT1), together with a group of naturalistic maintenance controls (MT2). We observed if the relapse rates would be different between 3 groups, to what extent the dose could be reduced, and if GDR patients could have improved functioning and quality of life.

RESULTS

A total of 96 patients, comprised 51, 24, and 21 patients in GDR, MT1, and MT2 groups, respectively. During follow-up, 14 patients (14.6%) relapsed, including 6, 4, and 4 from GDR, MT1, and MT2, statistically no difference between groups. In total, 74.5% of GDR patients could stay well under a lower dose, including 18 patients (35.3%) conducting 4 consecutive dose-tapering and staying well after reducing 58.5% of their baseline dose. The GDR group exhibited improved clinical outcomes and endorsed better quality of life.

CONCLUSIONS

GDR is a feasible approach as the majority of patients had a chance to taper antipsychotics to certain extents. Still, 25.5% of GDR patients could not successfully decrease any dose, including 11.8% experienced relapse, a risk comparable to their maintenance counterparts.

Minimal Effective Dose of Beans Required to Elicit a Significantly Lower Glycemic Response Than Commonly Consumed Starchy Foods: Predictions Based on In Vitro Digestion and Carbohydrate Analysis

Beans elicit lower glycemic responses (GRs) than other starchy foods, but the minimum effective dose (MED) to reduce GR is unknown. We sought to determine the MED of beans compared to common starchy foods. Overnight-fasted healthy volunteers consumed ¼c (phase 1, n = 24) or ½c (phase 2, n = 18) of black, cranberry, great northern, kidney, navy and pinto beans and corn, rice, pasta and potato (controls), with blood glucose measured before and for 2 h after eating. GRs (incremental areas under the curves, iAUCs) after beans were consumed were compared to those of controls by ANOVA followed by Dunnett's test. To qualify for MED, beans had to elicit an effective reduction in GR, defined as a statistically significant reduction in iAUC of ≥20% (i.e., a relative glycemic response, RGR, ≤80). Outcomes from in vitro digestion were compared with in vivo RGR. Both doses of all six beans effectively reduced GR versus all four starchy controls, except for ¼c and ½c cranberry and pinto vs. corn, ¼c great northern and navy vs. corn and ¼c navy and pinto vs. potato. MED criteria were met for 18 comparisons of the ¼c servings, with four of the remaining six met by the ½c servings. The overall mean ± SEM RGR vs. controls was similar for the ¼c and ½c servings: 53 ± 4% and 56 ± 3%, respectively. By multiple regression analysis, RGR = 23.3 × RDS + 8.3 × SDS - 20.1 × RS + 39.5 × AS - 108.2 (rapidly digested starch, p < 0.001; slowly digested starch, p = 0.054; resistant starch, p = 0.18; available sugars, p = 0.005; model r = 0.98, p = 0.001). RGR correlated with in vitro glucose release (r = 0.92, p < 0.001). The MED of beans is ¼ cup. For n = 30 comparisons (n = 24 beans vs. controls, n = 6 controls vs. each other), an effective reduction in GR was predicted from in vitro carbohydrate analysis with 86% sensitivity and 100% specificity.

Dose-tapering trajectories in patients with remitted psychosis undergoing guided antipsychotic reduction to reach minimum effective dose

BACKGROUND

Patients with remitted psychosis wish to reduce antipsychotic doses yet facing increased risks of relapse. Examining dose-tapering processes may provide insights to re-evaluate the risk-to-benefit balance. We aimed to depict and subgroup tapering trajectories, and explore factors associated with different dose-reduction patterns.

METHODS

A 2-year open-label randomized prospective comparative trial from August 2017 to September 2022 in Taiwan. Patients with a history of schizophrenia-related psychotic disorders under stable medications and symptoms were eligible, randomizing a proportion to conduct guided dose reduction. We depicted the trajectories of individual patients and named subgroups based on dose-tapering patterns. Predictors of baseline characteristics for designated subgroups were examined by logistic regression analysis; changes in outcomes were compared by paired t-test.

RESULTS

Fifty-one patients undergoing guided dose reduction, 18 (35.3%) reduced 4 steps consecutively (sequential reducers, SR), 14 (27.5%) reduced 1 to 3 steps (modest reducers, MR), 3 (5.9%) re-escalated to previous level (alert reducers, AR), 7 (13.7%) returned to baseline level (baseline returners, BR), 6 (11.7%) relapsed (failed reducers, FR) and 3 (5.9%) withdrew without relapse (early exits, EE). Patients with a history of relapse assumed a conservative dose-tapering pace; only the SR subgroup exhibited significant improvements in functioning and quality of life while failing to identify variables for predicting who would become SR or FR.

CONCLUSIONS

Guided dose reduction comprises dynamic processes with differences between individual trajectories. The proposed naming of dose-tapering patterns/subgroups provides a framework depicting patients undergoing dose-tapering. Longer-term observation and more flexible tapering approaches are anticipated to reveal favorable outcomes.

Minimum effective dose of oxytocin bolus during the caesarean section for patients at high vs low risk of uterine atony: A non-randomized, dual-arm, dose-finding prospective trial

Background and Aims

There are scanty data for oxytocin dose in patients at high risk of uterine atony. We aimed to compare the effective dose (ED) 90 of oxytocin for adequate uterine tone during the caesarean section in patients at high-risk vs low-risk uterine atony.

Methods

This dose-finding study was undertaken after ethical approval in non-labouring women aged >18 years with pre-defined risk factors for uterine atony (high-risk group) vs those without such factors (low-risk group) (n = 39 each). Starting dose of oxytocin in the first patient of low-risk and high-risk groups was 1 and 3 IU, respectively. Achieving adequate uterine tone at 3 min of oxytocin bolus was designated 'success', while inadequate tone constituted 'failure'. If the response was 'failure', the dose of oxytocin was increased for the next patient by 0.5 or 0.2 IU (high- and low-risk groups, respectively). In case of a successful response, the dose for the next patient was decreased with a probability of 1/9 using the same dosing intervals or otherwise kept unchanged.

Results

The ED90 (95% CI) of oxytocin bolus was 4.7 (3.3-6.0) IU for the high-risk group and 2.2 (1.3-3.2) IU for the low-risk group (P = 0.044). Oxytocin-associated tachycardia (P = 0.247) and hypotension (P = 0.675) were clinically greater for the high-risk vs low-risk group but statistically similar.

Conclusion

Non-labouring patients with high-risk factors for uterine atony require a greater dose of initial oxytocin bolus to achieve adequate uterine tone during the caesarean section compared to those without risk factors.

Weight-based oxytocin infusion for preventing uterine atony during caesarean delivery in non-labouring patients: A dose-response study

Postpartum haemorrhage remains a significant cause of maternal morbidity and mortality with the commonest reason being uterine atony. For prevention of uterine atony during caesarean delivery, oxytocin is advocated as a first line drug. There is however no published data regarding utility of a weight-based oxytocin infusion. The present study evaluated dose-response relationship for oxytocin infusion when used as weight-based regimen. A total of 55 non-labouring patients without risk factors for uterine atony and scheduled for caesarean delivery under spinal anaesthesia were enrolled. Randomization was done to receive oxytocin infusion in a dose of 0.1, 0.15, 0.2, 0.25 or 0.3 IU kg^-1  h^-1 (n = 11 each), initiated at the time of cord clamping and continued until the end of surgery. Successful outcome was defined as attaining an adequate uterine response at 4 min of initiation of infusion and maintained till end of surgery. Oxytocin associated hypotension, tachycardia, ST-T changes, nausea/vomiting, flushing and chest pain were also observed. A significant linear trend for adequate intraoperative uterine tone was seen with increasing dose of weight-based oxytocin infusion (P < 0.001). The effective dose in 90% population (ED90) was 0.29 IU kg^-1  h^-1 (95% CI = 0.25-0.42). Amongst the oxytocin associated side effects, a significant linear trend was seen between increasing dose of oxytocin infusion and hypotension as well as nausea/vomiting (p = 0.016 and 0.023 respectively). Thus, oxytocin infusion during caesarean delivery may be used as per the patient's body weight.

Protocol of guided antipsychotic reduction to reach minimum effective dose (GARMED) in patients with remitted psychosis based on pragmatic design

AIMS

Patients with psychosis intend to discontinue antipsychotic treatment for various reasons. As antipsychotic discontinuation involves a high risk of relapse, maintenance treatment is recommended by mainstream opinion even when remission is attained. To optimize the risk-to-benefit ratio of long-term antipsychotic treatment, we proposed an operationalized guided dose-reduction algorithm to serve as an intermediate approach as to achieve the lowest effective antipsychotic dose and better functioning for patients with remitted psychosis.

METHODS

Outpatients with a history of schizophrenia-related psychotic disorders currently under stable medications and symptoms are eligible to register in this protocol. Patients intending for dose reduction are randomized into 2:1, guided dose reduction group (GDR) versus maintenance treatment group (MTG1). Eligible patients who do not intend to reduce antipsychotics serve as naturalistic maintenance controls (MTG2). The GDR patients reduce no more than 25% of their baseline antipsychotic dose, with at least a 6-month stabilization period before reducing another 25% of their last dose. The timing of the next dose reduction will be determined by shared decision-making with the patient. Following a dose reduction, the patients will receive three consecutive monthly monitoring; otherwise, they receive treatment as usual.

DISCUSSION

By employing this pragmatic-based protocol, patients are empowered to evaluate their readiness for next dose reduction attempt. We would like to test in real-world situations if stable patients can reduce antipsychotics not at the expense of an increased risk of relapse, so as to optimize the balance between risk-to-benefit ratios of long-term antipsychotic treatment.

Challenging the Minimum Effective Antipsychotic Dose During Maintenance: Implications From 10-Year Follow-Up of First Episode Psychosis

Background: Contradictory messages regarding the necessity of long-term antipsychotic treatment after first episode psychosis arouse deliberations in clinical practice. We explored if there is an alternative beyond the dichotomy of maintenance treatment and discontinuation of medications. Methods: We conducted a retrospective observational study by reviewing medical records at the study hospital of a cohort of patients since their participation in an early psychosis study starting from 2006, with special interests in patients able to maintain good functioning under treatment with a low antipsychotic dose. Results: Of the 81 patients with first-episode psychosis, 55 patients (67.9%) had follow-up information for longer than 5 years. The majority (n = 46, 83.6%) had non-affective psychosis, 20 patients (36.4%) had full-time employment/education by the time of their latest visit; among them, 15 patients received dosage of antipsychotics no more than the minimum effective dose [chlorpromazine equivalent (CPZE) dose, 200 mg/day]. Besides, 10 of 55 patients (18.2%) only received very low dose antipsychotics (CPZE < 50 mg/day) during maintenance, which was significantly correlated to good functioning. Being male, having a history of hospitalization, and being on clozapine therapy were correlated to poorer functioning. Antipsychotic-free status was achieved only in two non-psychotic patients. Conclusions: A substantial proportion of patients could achieve good functioning under low-dose antipsychotic maintenance after first-episode psychosis, even if they could not completely withdraw antipsychotics in the long term. Optimizing the balance between preventing relapse and preserving functioning by fine-tuning antipsychotic dosage during maintenance is a challenge warranting more clinical attention.

Estimation of the Minimum Effective Dose of Dietary Supplement Crocetin for Prevention of Myopia Progression in Mice

The natural carotenoid crocetin has been reported to suppress phenotypes of an experimental myopia model in mice. We investigated the minimum effective dose to prevent myopia progression in a murine model. Three-week-old male mice (C57B6/J) were equipped with a −30 diopter (D) lens to induce myopia, and fed with normal chow, 0.0003%, or 0.001% of crocetin-containing chow. Changes in refractive errors and axial lengths (AL) were evaluated after three weeks. Pharmacokinetics of crocetin in the plasma and the eyeballs of mice was evaluated with specific high sensitivity quantitative analysis using liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine the minimum effective dosage. A concentration of 0.001% of crocetin-containing chow showed a significant (p < 0.001) suppressive effect against both refractive and AL changes in the murine model. Meanwhile, there was no significant difference of AL change between the 0.0003% and the normal chow groups. The concentration of crocetin in the plasma and the eyeballs from mice fed with 0.001% crocetin-containing chow was significantly higher than control and 0.0003% crocetin-containing chow. In conclusion, we suggest 0.001% of crocetin-containing extract is the minimum effective dose showing a significant suppressive effect against both refractive and AL changes in the murine model.

Phase II dose-response trials: A simulation study to compare analysis method performance under design considerations

Phase II trials are intended to provide information about the dose-response relationship and to support the choice of doses for a pivotal phase III trial. Recently, new analysis methods have been proposed to address these objectives, and guidance is needed to select the most appropriate analysis method in specific situations. We set up a simulation study to evaluate multiple performance measures of one traditional and three more recent dose-finding approaches under four design options and illustrate the investigated analysis methods with an example from clinical practice. Our results reveal no general recommendation for a particular analysis method across all design options and performance measures. However, we also demonstrate that the new analysis methods are worth the effort compared to the traditional ANOVA-based approach.

Identification of the minimum effective dose for normally distributed data using a Bayesian variable selection approach

The identification of the minimum effective dose is of high importance in the drug development process. In early stage screening experiments, establishing the minimum effective dose can be translated into a model selection based on information criteria. The presented alternative, Bayesian variable selection approach, allows for selection of the minimum effective dose, while taking into account model uncertainty. The performance of Bayesian variable selection is compared with the generalized order restricted information criterion on two dose-response experiments and through the simulations study. Which method has performed better depends on the complexity of the underlying model and the effect size relative to noise.

Glucosamine dose/concentration-effect correlation in the rat with adjuvant arthritis

There is a debate on the dose dependency, concentration-effect, hence, the beneficial effect of glucosamine (GlcN), a widely used anti-inflammatory natural product. We investigated dose/concentration-effect relationship and determined its minimum effective dose/concentration in rats with adjuvant arthritis (AA, Mycobacterium butyricum in squalene) both as preventive and ameliorating interventions. To control already emerged arthritis, rats received oral doses of placebo or 160 mg/kg.day(-1) GlcN for 6 days. For prevention, rats were orally administered 0, 20, 40, 80, or 160 mg/kg.day(-1) GlcN commencing on the day of adjuvant injection. The arthritis index (AI), serum nitrite, and body weight were recorded. Subsequently, animals were cannulated in the right jugular veins and blood samples were collected for the determination of GlcN. GlcN ameliorated and, dose-dependently, prevented AA. It also controlled nitrite. AI was inversely correlated with GlcN dose, maximum plasma concentration, and the area under the concentration curve. Minimum effective dose was approximately 40 mg/kg.day(-1) that correspond to maximum plasma concentration of 1.37 ± 0.24 mg/L, close to 1.6 mg/L reported for pharmaceutical grades of GlcN to humans. GlcN efficacy is dose and concentration dependent. If the data extrapolated to humans, a higher than the commonly tested 1500 mg/kg dosage regimen may provide more clear treatment outcomes.

Antidepressant-like activity of the adenosine A(2A) receptor antagonist, istradefylline (KW-6002), in the forced swim test and the tail suspension test in rodents

RATIONALE

Depression is common in Parkinson's disease (PD) but its response to classical antidepressants is not clear. The adenosine A2A antagonist istradefylline is effective in the treatment of the motor symptoms of PD but inhibition of the adenosine A2A receptor may also induce antidepressant-like effects.

OBJECTIVE

We have investigated whether istradefylline might be effective in treating depression in PD using the forced swimming test (FST) and the tail suspension test (TST) in rodents.

RESULTS

Istradefylline significantly decreased immobility time in the FST in both rats and mice (0.16mg/kg and higher) with comparable efficacy to an equivalent dose of the tricyclic antidepressants, desipramine and imipramine. Both 8-OH-DPAT (5-HT1A agonist) and quinpirole (D2 agonist) also reduced the immobility time. The istradefylline-induced reduction of immobility time was attenuated by corticosterone. In addition, the combined use of a sub-threshold dose of istradefylline and the serotonin-noradrenaline reuptake inhibitor venlafaxine ameliorated depression-like behavior in the mouse FST. In the mouse TST, istradefylline (0.08mg/kg and higher) decreased immobility time. Moreover, co-administration of istradefylline with paroxetine or fluoxetine (selective serotonin reuptake inhibitors) or deprenyl (MAO-B inhibitor) at doses that did not show antidepressant-like effects when administered alone, resulted in a significant reduction in immobility time.

CONCLUSIONS

Istradefylline alone or co-administered with currently available antidepressants, may be useful for the treatment of depression as well as motor symptoms of PD. Its effects might be, at least in part, attributable to modulation of hypothalamic-pituitary-adrenal axis.

ASP6537, a novel highly selective cyclooxygenase-1 inhibitor, exerts potent antithrombotic effect without "aspirin dilemma"

INTRODUCTION

Aspirin inhibits both the cyclooxygenase (COX)-1-dependent production of thromboxane A2 (TXA2) in platelets and COX-2-dependent production of anti-aggregatory prostaglandin I2 (PGI2) in vessel walls, resulting in "aspirin dilemma." Our objective is to investigate whether ASP6537 can overcome aspirin dilemma and exert a potent antithrombotic effect without a concurrent ulcerogenic effect.

METHODS

We evaluated the inhibitory effects of ASP6537 on recombinant human COX-1 (rhCOX-1) and rhCOX-2 activities using a COX-1/2 selectivity test. To determine whether ASP6537 induces aspirin dilemma, we examined the effects of ASP6537 on in vitro TXA2 and PGI2 metabolite production from platelets and isolated aorta of guinea pigs, and on plasma concentrations of TXA2 and PGI2 metabolites in aged rats. Finally, we evaluated the antithrombotic effects and ulcerogenic activity of ASP6537 using an electrically induced carotid arterial thrombosis model and a gastric ulcer model in guinea pigs.

RESULTS

The IC50 ratios of rhCOX-2 to rhCOX-1 for ASP6537 and aspirin were >142,000 and 1.63 fold, respectively. ASP6537 inhibited TXA2 production more selectively than aspirin in in vitro and in vivo TXA2/PGI2 production studies. ASP6537 exerted a significant antithrombotic effect at ≥3 mg/kg, while aspirin tended to inhibit thrombosis at 300 mg/kg but it was not statistically significant. Further, ASP6537 did not induce ulcer formation at 100 mg/kg, whereas aspirin exhibited an ulcerogenic effect at doses of ≥100 mg/kg.

CONCLUSIONS

ASP6537 functions as a highly selective COX-1 inhibitor with a superior ability to aspirin for normalizing TXA2/PGI2 balance, and exerts antithrombotic effect without ulcerogenic effect.

Efficacy and safety of low dose desmopressin orally disintegrating tablet in women with nocturia: results of a multicenter, randomized, double-blind, placebo controlled, parallel group study

PURPOSE

Previous studies suggest a lower dose of desmopressin orally disintegrating tablet may be effective in females compared to males with nocturia. We confirm the efficacy and safety of 25 μg desmopressin orally disintegrating tablet compared to placebo in female patients.

MATERIALS AND METHODS

In this 3-month, randomized, double-blind, parallel group study 25 μg desmopressin once daily was compared to placebo in women with nocturia (2 or more nocturnal voids). The co-primary efficacy end points were change from baseline in mean number of nocturnal voids and proportion of patients achieving at least a 33% reduction from baseline in the mean number of nocturnal voids (33% responders).

RESULTS

The full analysis set comprised 261 patients (age range 19 to 87 years). Desmopressin significantly reduced the mean number of nocturnal voids and increased the odds of a 33% or greater response compared to placebo during 3 months, assessed by longitudinal analysis (-0.22, p = 0.028 and OR 1.85, p = 0.006, respectively). Desmopressin increased the mean time to first nocturnal void by 49 minutes compared to placebo at 3 months (p = 0.003). The response to desmopressin was seen by week 1 of treatment and was sustained throughout the trial. Significant increases in health related quality of life and sleep quality were observed compared to placebo. Desmopressin was well tolerated. Serum sodium levels remained greater than 125 mmol/L throughout the trial and 3 transient decreases to less than 130 mmol/L were recorded.

CONCLUSIONS

At a dose of 25 μg, desmopressin orally disintegrating tablet is an effective and well tolerated treatment for women with nocturia. Treatment provides rapid and sustained improvement in nocturia and quality of life.

Expected loss functions as additional measures to assess performance of multiple testing procedures for combination drug dose finding

There are several measures that are commonly used to assess performance of a multiple testing procedure (MTP). These measures include power, overall error rate (family-wise error rate), and lack of power. In settings where the MTP is used to estimate a parameter, for example, the minimum effective dose, bias is of interest. In some studies, the parameter has a set-like structure, and thus, bias is not well defined. Nevertheless, the accuracy of estimation is one of the essential features of an MTP in such a context. In this paper, we propose several measures based on the expected values of loss functions that resemble bias. These measures are constructed to be useful in combination drug dose response studies when the target is to identify all minimum efficacious drug combinations. One of the proposed measures allows for assigning different penalties for incorrectly overestimating and underestimating a true minimum efficacious combination. Several simple examples are considered to illustrate the proposed loss functions. Then, the expected values of these loss functions are used in a simulation study to identify the best procedure among several methods used to select the minimum efficacious combinations, where the measures take into account the investigator's preferences about possibly overestimating and/or underestimating a true minimum efficacious combination. The ideas presented in this paper can be generalized to construct measures that resemble bias in other settings. These measures can serve as an essential tool to assess performance of several methods for identifying set-like parameters in terms of accuracy of estimation.