A phase II/pharmacokinetic trial of high-dose progesterone in combination with paclitaxel

Association of digoxin therapy with case fatality rate in acute pulmonary embolism

OBJECTIVE

Despite wide usage of digoxin for various diseases in cardiology practice, its benefit is controversial and moreover it had been associated with unfavorable outcomes in some previous studies. The aim of this present study was to demonstrate whether digoxin usage was related with worse outcomes or not in patients with acute pulmonary embolisms.

METHODS

A total number of 1215 patients retrospectively enrolled for the study. Basic demographic features, pulmonary embolism severity index (PESI) scores, laboratory parameters and medications of patients who had been diagnosed with acute pulmonary embolism were recorded. Short (30 days) and long-term mortality were reported as the clinical outcomes.

RESULTS

Total mortality was 15.4% in the study population and 78 of these subjects died within the first 30 days. The frequency of digoxin treatment was 8% and most of these patients were prior users. According to the binary logistic regression analyses the PESI score, right ventricle (RV) diastolic diameter, systolic pulmonary arterial pressure (sPAP), brain natriuretic peptide (BNP), troponin and digoxin therapy (odds ratio, OR: 2.82 95% confidence interval, CI: 1.39-8.31, P = 0.03) were found as independent predictors of short-term mortality. Beside these findings; sPAP, PESI score, RV diastolic diameter and digoxin therapy (hazard ratio, HR: 2.11 95%CI: 1.22-7.31, P = 0.03) were determined as independent predictors of long-term mortality in Cox regression analyses. In subgroup analysis, we determined significantly greater increase in short-term mortality with use of digoxin among patients who had chronic renal disease, among patients under thrombolytic therapy and under high dosage of digoxin therapy and among female patients.

CONCLUSION

Digoxin has been used extensively for decades in the treatment of heart failure and arrhythmias despite some controversies over its benefit. For the first time in the literature, we have demonstrated independent association of digoxin therapy with short-term and long-term mortality in patients with acute pulmonary embolism.

Progesterone loading as a strategy for treating postpartum depression

Postpartum depression (PPD) is a severe disorder that adversely impacts both mothers and infants. It is associated with significant morbidity and mortality and reported prevalence is 11.5% (Ko, Rockhill, Tong, Morrow, & Farr. (2017). MMWR Morbidity and Mortality Weekly Report, 66(6), 153-158). Although PPD's fundamental pathophysiology remains to be fully illuminated, the influence of changes in perinatal hormones such as allopregnanolone (an endogenous progesterone metabolite) are most promising avenues of research. Conventional treatments for PPD are aligned with treatment strategies for depressive disorders. Brexanolone is a small molecule, neuroactive steroid GABA_A receptor allosteric modulator consisting of synthetic allopregnanolone and a solubilizing agent. In early 2019, brexanolone received approval in the United States for the treatment of PPD. Brexanolone is only available through a restricted program and is costly. Animal models demonstrate that progesterone prevents depression-like behaviors. However, studies of progesterone's effects in women suffering from PPD are few and inconclusive. We hypothesize that orally dosed progesterone will increase concentrations of allopregnanolone in the central nervous system, which should relieve symptoms of PPD.

Progesterone treatment reduces neuroinflammation, oxidative stress and brain damage and improves long-term outcomes in a rat model of repeated mild traumatic brain injury

BACKGROUND

Repeated mild traumatic brain injuries, such as concussions, may result in cumulative brain damage, neurodegeneration and other chronic neurological impairments. There are currently no clinically available treatment options known to prevent these consequences. However, growing evidence implicates neuroinflammation and oxidative stress in the pathogenesis of repetitive mild brain injuries; thus, these may represent potential therapeutic targets. Progesterone has been demonstrated to have potent anti-inflammatory and anti-oxidant properties after brain insult; therefore, here, we examined progesterone treatment in rats given repetitive mild brain injuries via the repeated mild fluid percussion injury model.

METHODS

Male Long-Evans rats were assigned into four groups: sham injury + vehicle treatment, sham injury + progesterone treatment (8 mg/kg/day), repeated mild fluid percussion injuries + vehicle treatment, and repeated mild fluid percussion injuries + progesterone treatment. Rats were administered a total of three injuries, with each injury separated by 5 days. Treatment was initiated 1 h after the first injury, then administered daily for a total of 15 days. Rats underwent behavioural testing at 12-weeks post-treatment to assess cognition, motor function, anxiety and depression. Brains were then dissected for analysis of markers for neuroinflammation and oxidative stress. Ex vivo MRI was conducted in order to examine structural brain damage and white matter integrity.

RESULTS

Repeated mild fluid percussion injuries + progesterone treatment rats showed significantly reduced cognitive and sensorimotor deficits compared to their vehicle-treated counterparts at 12-weeks post-treatment. Progesterone treatment significantly attenuated markers of neuroinflammation and oxidative stress in rats given repeated mild fluid percussion injuries, with concomitant reductions in grey and white matter damage as indicated by MRI.

CONCLUSIONS

These findings implicate neuroinflammation and oxidative stress in the pathophysiological aftermath of mild brain injuries and suggest that progesterone may be a viable treatment option to mitigate these effects and their detrimental consequences.

Assessing reproductive status/stages in mice

The short reproductive cycle length observed in rodents, called the estrous cycle, makes them an ideal animal model for investigation of changes that occur during the reproductive cycle. Most of the data in the literature about the estrous cycle is obtained from rats because they are easily manipulated and they exhibit a clear and well-defined estrous cycle. However, the increased number of experiments using knockout mice requires identification of their estrous cycle as well, since (in)fertility issues may arise. In mice, like rats, the identification of the stage of estrous cycle is based on the proportion of cell types observed in the vaginal secretion. The aim of this unit is to provide guidelines for quickly and accurately determining estrous cycle phases in mice.

Polymeric and Low Molecular Mass Efflux Pump Inhibitors for Oral Drug Delivery

Transmembrane located transporter proteins can be responsible for the low bioavailability of orally administered drugs. Drug delivery systems which can overcome this barrier caused by efflux pumps are therefore highly on demand. Within the current review, intestinal located efflux transporters, methods to identify efflux pump substrates and inhibitors as well as strategies to minimize efflux pump mediated transport of drugs are discussed. Methods include in silico screening, transport and accumulation studies and monitoring of the ATPase activity. An emphasis has been placed on efflux pump inhibitors including low molecular mass inhibitors such as cyclosporine, PSC833 or KR30031 and polymeric inhibitors such as myrj, thiomers and cremophor EL. Also formulation approaches to circumvent intestinal segments with high efflux pump expression are briefly addressed.

Steady-state serum concentrations of progesterone following continuous intravenous infusion in patients with acute moderate to severe traumatic brain injury

Progesterone (PG) has been shown to provide substantial neuroprotection after traumatic brain injury (TBI) in multiple animal models. As a first step in assessing applicability to humans, the authors examined the effects of acute TBI and extracranial trauma on the pharmacokinetics of PG given by intravenous infusion. Multiple blood samples were obtained from 11 female and 21 male trauma patients receiving PG and 1 female and 3 male patients receiving placebo infusions for 72 hours. Values for C(SS), CL, t(1/2), and Vd were obtained using AUC((0-72)) and postinfusion blood samples. C(SS) values were 337 +/- 135 ng/mL, which were significantly lower than the target concentration of 450 +/- 100 ng/mL. The lower C(SS) is attributed to the CL, which was higher than anticipated. In addition, t(1/2) was longer and V(d) was higher than anticipated. These results demonstrate that stable PG concentrations can be rapidly achieved following TBI.

Evaluation of a Sex-Based Difference in the Pharmacokinetics of Digoxin

STUDY OBJECTIVE

To determine whether a sex-based difference in digoxin pharmacokinetics exists in patients receiving long-term digoxin therapy for chronic heart failure or atrial fibrillation.

DESIGN

Single-center, retrospective review of medical records.

SETTING

University-based teaching hospital and outpatient clinic.

PATIENTS

Sixty-seven adults (32 men, 35 women) with chronic heart failure or atrial fibrillation who were receiving digoxin therapy.

MEASUREMENTS AND MAIN RESULTS

Serum digoxin concentrations and daily digoxin doses were obtained from patients' medical records. Daily doses were adjusted for patients' actual and ideal body weight and body mass index (BMI). The ratio between the serum digoxin concentration and each of the adjusted daily doses of digoxin was compared between men and women. The mean +/- SD serum digoxin concentration was 0.85 +/- 0.51 ng/ml for men compared with 1.02 +/- 0.51 ng/ml for women. Mean +/- SD unadjusted doses of digoxin were 0.180 +/- 0.063 and 0.164 +/- 0.059 mg/day for men and women, respectively; the difference was not statistically significant. Ratios of serum digoxin concentration to daily digoxin doses did not differ by sex when doses were estimated with actual or ideal weight. Only the ratio of the digoxin concentration to the BMI-adjusted dose was significantly different between men and women (0.14 +/- 0.09 and 0.19 +/- 0.11, respectively, p<0.05).

CONCLUSION

Sex-based differences in digoxin pharmacokinetics were absent when actual or ideal body weight was used. However, the ratio of serum digoxin concentration to daily digoxin dose adjusted for BMI differed by sex. Because digoxin is distributed to lean body mass, use of the BMI could have overadjusted body weight, leading to inaccurate pharmacokinetic assumptions and calculations. The pharmacokinetics of digoxin do not appear to differ by sex.

The impact of risk status, preexisting morbidity, and polypharmacy on treatment decisions concerning menopausal symptoms

Because each menopausal treatment has a unique benefit-risk profile, deciding whether menopausal hormone therapy (HT) or another menopausal treatment is appropriate for an individual requires assessing the risks and benefits of each treatment as well as determining the patient's risk factors, comorbidities, and current medications. Simple summary metrics for assessing net treatment effects on multiple outcomes, such as the Women's Health Initiative's (WHI) global index, are not necessarily generalizable beyond the study population in which they were derived. However, trial evidence can be translated to individual decisions by transforming relative risks into absolute risks. The validity of generalizing relative risks found in clinical trials to groups with differing baseline risks depends on the homogeneity of relative risks across various risk strata. Subgroup analyses from the major clinical studies of HT found its relative risks for cardiovascular disease, hip fracture, breast cancer, colorectal cancer, and ovarian cancer to be relatively uniform across strata defined by age, race/ethnicity, antecedent risk status, or prior disease. The number of significant subgroup findings in these studies tended to match the number expected by chance alone. However, data are limited for many subgroups, especially those with comorbidities. Strata defined by the concurrent use of drugs that can interact with HT are not expected to be homogeneous, yet data on drug interactions are limited. More data are needed about the effects of menopausal treatments in diverse populations, and more attention is needed to translate this evidence into clinical practice and to develop tools to support informed decision making.

NEW 4-ARYL-1,4-DIHYDROPYRIDINES AND 4-ARYLPYRIDINES AS P-GLYCOPROTEIN INHIBITORS

Efflux of cytotoxic agents mediated by P-glycoprotein is believed to be an important mechanism of multidrug resistance, which remains a serious limitation to successful chemotherapy in cancers such as metastatic breast cancer. A series of 4-aryl-1,4-dihydropyridines and corresponding aromatized 4-arylpyridines have been synthesized based on structure modifications of niguldipine to enhance multidrug resistance reversal activity, while minimizing calcium channel binding. Thirty new compounds were characterized. [(3)H]Vinblastine accumulation studies indicated that at a concentration level of 3 muM, 15 of 18 4-aryl-1,4-dihydropyridines and all 4-arylpyridines can successfully restore intracellular accumulation of vinblastine in a resistant human breast adenocarcinoma cell line, MCF-7/adr, which overexpresses P-glycoprotein. The most potent compounds led to an approximately 15-fold increase of vinblastine accumulation. All of the test compounds that significantly increased vinblastine accumulation in MCF/adr cells were able to substantially reduce IC(50) values of daunomycin and increase its cytotoxicity in MCF-7/adr-resistant cells, confirming the results of the vinblastine accumulation studies. Calcium channel binding assays for these newly synthesized compounds were conducted using rat cerebral cortex membrane. All but eight compounds demonstrated negligible calcium channel binding over the concentration range from 15 to 2500 nM. The results demonstrate that the newly synthesized series of 1,4-dihydropyridines and pyridines represent P-glycoprotein modulators with negligible calcium channel blocking activity.

Sex-based differences in the effect of digoxin for the treatment of heart failure

BACKGROUND

The Digitalis Investigation Group trial reported that treatment with digoxin did not decrease overall mortality among patients with heart failure and depressed left ventricular systolic function, although it did reduce hospitalizations slightly. Even though the epidemiologic features, causes, and prognosis of heart failure vary between men and women, sex-based differences in the effect of digoxin were not evaluated.

METHODS

We conducted a post hoc subgroup analysis to assess whether there were sex-based differences in the effect of digoxin therapy among the 6800 patients in the Digitalis Investigation Group study. The presence of an interaction between sex and digoxin therapy with respect to the primary end point of death from any cause was evaluated with the use of Mantel-Haenszel tests of heterogeneity and a multivariable Cox proportional-hazards model, adjusted for demographic and clinical variables.

RESULTS

There was an absolute difference of 5.8 percent (95 percent confidence interval, 0.5 to 11.1) between men and women in the effect of digoxin on the rate of death from any cause (P=0.034 for the interaction). Specifically, women who were randomly assigned to digoxin had a higher rate of death than women who were randomly assigned to placebo (33.1 percent vs. 28.9 percent; absolute difference, 4.2 percent, 95 percent confidence interval, -0.5 to 8.8). In contrast, the rate of death was similar among men randomly assigned to digoxin and men randomly assigned to placebo (35.2 percent vs. 36.9 percent; absolute difference, -1.6 percent; 95 percent confidence interval, -4.2 to 1.0). In the multivariable analysis, digoxin was associated with a significantly higher risk of death among women (adjusted hazard ratio for the comparison with placebo, 1.23; 95 percent confidence interval, 1.02 to 1.47), but it had no significant effect among men (adjusted hazard ratio, 0.93; 95 percent confidence interval, 0.85 to 1.02; P=0.014 for the interaction).

CONCLUSIONS

The effect of digoxin therapy differs between men and women. Digoxin therapy is associated with an increased risk of death from any cause among women, but not men, with heart failure and depressed left ventricular systolic function.

The mucosa of the small intestine: how clinically relevant as an organ of drug metabolism?

The intestinal mucosa is capable of metabolising drugs via phase I and II reactions. Increasingly, as a result of in vitro and in vivo (animal and human) data, the intestinal mucosa is being implicated as a major metabolic organ for some drugs. This has been supported by clinical studies of orally administered drugs (well-known examples include cyclosporin, midazolam, nifedipine and tacrolimus) where intestinal drug metabolism has significantly reduced oral bioavailability. This review discusses the intestinal properties and processes that contribute to drug metabolism. An understanding of the interplay between the processes controlling absorption, metabolism and P-glycoprotein-mediated efflux from the intestinal mucosa into the intestinal lumen facilitates determination of the extent of the intestinal contribution to first-pass metabolism. The clinical relevance of intestinal metabolism, however, depends on the relative importance of the metabolic pathway involved, the therapeutic index of the drug and the inherent inter- and intra-individual variability. This variability can stem from genetic (metabolising enzyme polymorphisms) and/or non-genetic (including concomitant drug and food intake, route of administration) sources. An overwhelming proportion of clinically relevant drug interactions where the intestine has been implicated as a major contributor to first-pass metabolism involve drugs that undergo cytochrome P450 (CYP) 3A4-mediated biotransformation and are substrates for the efflux transporter P-glycoprotein. Much work is yet to be done in characterising the clinical impact of other enzyme systems on drug therapy. In order to achieve this, the first-pass contributions of the intestine and liver must be successfully decoupled.

Subgroup interactions in the Heart and Estrogen/Progestin Replacement Study: lessons learned

BACKGROUND

The Heart and Estrogen/Progestin Replacement Study (HERS) showed no overall benefit of postmenopausal hormone treatment in women with coronary heart disease (CHD). We analyzed the HERS data to determine whether there were specific subgroups of women who responded differently to treatment, either during the first year or in the overall study.

METHODS AND RESULTS

In the search for significant treatment interactions, we analyzed a total of 86 subgroups defined by baseline characteristics. These included demographics and lifestyle factors, laboratory and physical examination variables, medical history and symptoms by self-report, medication use, and prior CHD history by chart review. We examined within-subgroup treatment effects for baseline variables that significantly interacted with treatment assignment. Under the null hypothesis, 4 (5%) of the 86 interactions would be expected to be nominally significant (P<0.05) by chance alone at each time point. Six of the interaction values were P<0.05 at 1 year, and 3 were P<0.05 at trial completion. The findings are discussed in the context of known mechanisms of action and prior scientific knowledge. Use of digitalis and history of myocardial infarction emerged as 2 possible modifiers of the effect of hormone therapy during the first year, and lipoprotein(a) emerged as a possible modifier during the overall study.

CONCLUSIONS

Extensive post hoc analyses did not identify any subgroup of HERS participants in which postmenopausal hormone treatment was clearly beneficial or harmful, but several possibilities emerged for testing in future trials.

Drug interactions with the taxanes: clinical implications

BACKGROUND

The taxanes paclitaxel and docetaxel are among the most active antitumor agents. Clinically important pharmacodynamic interactions have been reported to occur with these agents that are sequence or schedule dependent. Because the taxanes undergo hepatic oxidation via the cytochrome P450 system, pharmacokinetic interactions due to enzyme induction or inhibition can also occur.

METHODS

A comprehensive literature search was conducted using Medline to identify clinically important drug-interactions with the taxanes.

RESULTS

Clinically significant taxane interactions were identified for carboplatin, cisplatin, doxorubicin, docetaxel, epirubicin and anticonvulsants. Doxorubicin and epirubicin should be administered 24 h before paclitaxel, and the cumulative anthracycline dose limited to 360 mg/m(2). This will prevent the enhanced toxicities due to sequence and schedule dependent interactions between anthracyclines and paclitaxel. Conversely, paclitaxel should be administered at least 24 h before cisplatin to avoid a decrease in clearance and increase in myelosuppression. With concurrent anticonvulsant therapy, cytochrome p450 enzyme induction results in decreased paclitaxel plasma steady state concentrations, possibly requiring an increased dose of paclitaxel. A number of other drug interactions have been reported in preliminary studies for which clinical significance has yet to be established.

CONCLUSION

Clinically significant drug interactions have been reported to occur when paclitaxel is administered with doxorubicin, cisplatin, or anticonvulsants (phenytoin, carbamazepine, and phenobarbital).

Phase I study of cinchonine, a multidrug resistance reversing agent, combined with the CHVP regimen in relapsed and refractory lymphoproliferative syndromes

Overexpression of P-glycoprotein (P-gp) in cancer cells reduces intracellular accumulation of various anticancer drugs including anthracyclines and vinca alkaloids. This multidrug resistance (MDR) phenotype can be reversed in vitro by a number of non-cytotoxic drugs. We have identified the quinine's isomer cinchonine as a potent MDR reversing agent, both in vitro and in animal models. Here, we report an open phase I dose escalation trial in patients with refractory or relapsed malignant lymphoid diseases. Cinchonine dihydrochloride was administered by continuous i.v. infusion for 48 h and escalated over five dose levels ranging from 15 to 35 mg/kg/d. Cinchonine infusion started 24 h before i.v. doxorubicin (25 mg/m2), vinblastine (6 mg/m2), cyclophosphamide (600 mg/m2) and methylprednisolone (1 mg/kg/d) (CHVP regimen) and lasted for 24 h after chemotherapy infusion. Thirty-four patients received 87 cycles of CHVP/cinchonine. The MTD of cinchonine administered by continuous i.v. infusion was 30 mg/kg/d. Prolonged cardiac repolarization was the main dose-limiting toxicity. No ventricular arrhythmia including 'torsade de pointes' was observed. An MDR reversing activity was identified in the serum from every patient and correlated with cinchonine serum level. When infused at 30 mg/kg/d, cinchonine demonstrated a limited influence on doxorubicin pharmacokinetic. We conclude that i.v. infusion of cinchonine might be started 12 h before MDR-related chemotherapy infusion and requires continuous cardiac monitoring but no reduction of cytotoxic drug doses.