Time-variant increase in methylprednisolone clearance in patients with acute respiratory distress syndrome: a population pharmacokinetic study

Meta-Analysis of the Input and Disposition of Various Dosage Forms of Methylprednisolone in Healthy Subjects Utilizing a Physiologically Based Pharmacokinetic Model

The study quantitatively analyzes and compares the pharmacokinetics (PK) of methylprednisolone (MPL) in humans upon administration of various dosage forms. The PK parameters and profiles of MPL in healthy subjects were collected from 22 literature sources. A minimal physiologically based pharmacokinetic (mPBPK) model consisting of blood and two tissue (lumped liver and kidney, remainder) compartments with nonlinear tissue partitioning was applied to describe MPL disposition. Overall 18 plasma concentration profiles were well captured and 85% of PK parameters reasonably estimated. The clearance (CL) of MPL averaged 336 mL/h/kg and appeared slightly nonlinear across a dosage range of 5 to 800 mg, the distribution volume (Vd) averaged 1.17 L/kg, and the model predicted elimination half-life (t1/2) was 2.6 h. Rapid prodrug conversion was found for intravenous MPL sodium succinate (MPSS) with a t1/2 of 1.7 min, and followed by MPL phosphate (MPPS) 3.8 min, MPL hemisuccinate (MPHS) 16 min, and MPL suleptanate (MPSP) 2.9 h. Their bioavailabilities (F) varied slightly from 60 to 73%. Intramuscular doses showed an absorption rate constant (ka) of 1.5 h-1 for MPSS and 96 h-1 for MPSP. Oral doses of 5 formulations were examined. Medrol exhibited greatest absorption with F of 74% and ka of 2.1 h-1, while one generic product had F of 32.6%. This study demonstrated the utility of a mechanistic mPBPK disposition model for comparing MPL formation from various esters, absorption from several oral dose formulations, and modest variability across numerous PK studies in healthy humans.

Small volume rapid equilibrium dialysis (RED) measures effects of interstitial parameters on the protein-bound fraction of topical drugs

The importance of plasma protein binding in the early stages of drug development is well recognized. Free and bound drug fractions in plasma are routinely determined with well-established methods. However, for physiological fluids with a small accessible volume and low protein concentrations, such as dermal interstitial fluid (dISF) validated methods are currently missing. Due to the low protein concentration and highly dynamic processes in the dermis, protein binding data obtained from plasma samples may underestimate in-vivo efficacy. This study aimed to validate a small volume rapid equilibrium dialysis (RED) for low protein samples, as a tool to examine drug-protein binding directly in the biological fluid at the site of action. The sample volume required for RED was successfully downscaled to 50 µl and plasma protein binding values of the four model drugs were consistent with previous studies with an average recovery of 88 ± 8% which makes all tested drugs suitable for small volume RED. Inter- and intra-batch variability showed sufficient reproducibility across RED plates. Small volume RED was successfully applied to assess the effects of interstitial parameters, including the evaluation of the major binding protein and the effects of binding protein concentration, drug concentration, and pH on the protein-bound drug fraction using 2% HSA and/or diluted human plasma as a surrogate for dISF.

Theory and Practice of Glucocorticoids in COVID-19: Getting to the Heart of the Matter-A Critical Review and Viewpoints

Prolonged, low-dose glucocorticoids (GCs) have shown the highest efficacy among pharmacological and non-pharmacological treatments for COVID-19. Despite the World Health Organization's recommendation against their use at the beginning of the pandemic, GCs at a dose equivalent to dexamethasone 6 mg/day for 10 days are now indicated in all COVID-19 cases who require respiratory support. However, the efficacy of the intervention depends on the timing of initiation, the dose, and other individual factors. Indeed, patients treated with similar GC protocols often experience different outcomes, which do not always correlate with the presence of comorbidities or with the severity of respiratory involvement at baseline. This prompted us to critically review the literature on the rationale, pharmacological principles, and clinical evidence that should guide GC treatment. Based on these data, the best treatment protocol probably involves an initial bolus dose to saturate the glucocorticoid receptors, followed by a continuous infusion to maintain constant plasma levels, and eventually a slow tapering to interruption. Methylprednisolone has shown the highest efficacy among different GC molecules, most likely thanks to its higher ability to penetrate the lung. Decreased tissue sensitivity to glucocorticoids is thought to be the main mechanism accounting for the lower response to the treatment in some individuals. We do not have a readily available test to identify GC resistance; therefore, to address inter-individual variability, future research should aim at investigating clinical, physiological, and laboratory markers to guide a personalized GC treatment approach.

The impact of sepsis on hepatic drug metabolism in critically ill patients: a narrative review

INTRODUCTION

Hepatic drug metabolism is important in improving drug dosing strategies in sepsis. Pharmacokinetics in the critically ill population are severely altered due to changes in absorption, distribution, excretion and metabolization. Hepatic drug metabolism might be altered due to changes in hepatic blood flow, drug metabolizing protein availability, and protein binding. The purpose of this review is to examine evidence on whether hepatic drug metabolism is significantly affected in septic patients, and to provide insights in the need for future research.

AREAS COVERED

This review describes the effect of sepsis on hepatic drug metabolism in humans. Clinical trials, pathophysiological background information and example drug groups are further discussed. The literature search has been conducted in Embase, Medline ALL Ovid, and Cochrane CENTRAL register of trials.

EXPERT OPINION

Limited research has been conducted on drug metabolism in the sepsis population, with some trials having researched healthy individuals using endotoxin injections. Notwithstanding this limitation, hepatic drug metabolism seems to be decreased for certain drugs in sepsis. More research on the pharmacokinetic behavior of hepatic metabolized drugs in sepsis is warranted, using inflammatory biomarkers, hemodynamic changes, mechanical ventilation, organ support, and catecholamine infusion as possible confounders.

Low-dose methylprednisolone treatment in critically ill patients with severe community-acquired pneumonia

Purpose

Severe community-acquired pneumonia (CAP) requiring intensive care unit admission is associated with significant acute and long-term morbidity and mortality. We hypothesized that downregulation of systemic and pulmonary inflammation with prolonged low-dose methylprednisolone treatment would accelerate pneumonia resolution and improve clinical outcomes.

Methods

This double-blind, randomized, placebo-controlled clinical trial recruited adult patients within 72–96 h of hospital presentation. Patients were randomized in 1:1 ratio; an intravenous 40 mg loading bolus was followed by 40 mg/day through day 7 and progressive tapering during the 20-day treatment course. Randomization was stratified by site and need for mechanical ventilation (MV) at the time of randomization. Outcomes included a primary endpoint of 60-day all-cause mortality and secondary endpoints of morbidity and mortality up to 1 year of follow-up.

Results

Between January 2012 and April 2016, 586 patients from 42 Veterans Affairs Medical Centers were randomized, short of the 1420 target sample size because of low recruitment. 584 patients were included in the analysis. There was no significant difference in 60-day mortality between the methylprednisolone and placebo arms (16% vs. 18%; adjusted odds ratio 0.90, 95% CI 0.57–1.40). There were no significant differences in secondary outcomes or complications.

Conclusions

In patients with severe CAP, prolonged low-dose methylprednisolone treatment did not significantly reduce 60-day mortality. Treatment was not associated with increased complications.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00134-022-06684-3.

Biocompatible N-acetyl-nanoconstruct alleviates lipopolysaccharide-induced acute lung injury in vivo

Oxidative stress plays important roles in inflammatory responses during acute lung injury (ALI). Recently, nanoconstruct (Nano)-based drug-delivery systems have shown promise in many models of inflammation. In this study, we evaluated the anti-inflammatory effects of N-acetylcysteine (NAC) loaded in a biocompatible Nano using a rat model of ALI. We synthesized a Nano with a good NAC-releasing capacity using porous silica Nano, which was used to produce Nano/NAC complexes. For in vivo experiments, Sprague–Dawley rats were intraperitoneally administered NAC or Nano/NAC 30 min after intratracheal instillation of lipopolysaccharide. After 6 h, bronchoalveolar lavage fluids and lung tissues were collected. The anti-oxidative effect of the Nano/NAC complex was confirmed by demonstrating reduced levels of reactive oxygen species after treatment with the Nano/NAC in vitro. In vivo experiments also showed that the Nano/NAC treatment may protect against LPS‐induced ALI thorough anti‐oxidative and anti‐inflammatory effects, which may be attributed to the inactivation of the NF‐κB and MAPK pathways. In addition, the effects of Nano/NAC treatment were shown to be superior to those of NAC alone. We suggest the therapeutic potential of Nano/NAC treatment as an anti‐inflammatory agent against ALI. Furthermore, our study can provide basic data for developing nanotechnology-based pharmacotherapeutics for ALI.

Tailoring glucocorticoids in patients with severe COVID-19: a narrative review

OBJECTIVE

To discuss the pathogenesis of severe coronavirus disease 2019 (COVID-19) infection and the pharmacological effects of glucocorticoids (GCs) toward this infection. To review randomized controlled trials (RCTs) using GCs to treat patients with severe COVID-19, and investigate whether GC timing, dosage, or duration affect clinical outcomes. Finally. to discuss the use of biological markers, respiratory parameters, and radiological evidence to select patients for improved GC therapeutic precision.

BACKGROUND

COVID-19 has become an unprecedented global challenge. As GCs have been used as key immunomodulators to treat inflammation-related diseases, they may play key roles in limiting disease progression by modulating immune responses, cytokine production, and endothelial function in patients with severe COVID-19, who often experience excessive cytokine production and endothelial and renin-angiotensin system (RAS) dysfunction. Current clinical trials have partially proven this efficacy, but GC timing, dosage, and duration vary greatly, with no unifying consensus, thereby creating confusion.

METHODS

Publications through March 2021 were retrieved from the Web of Science and PubMed. Results from cited references in published articles were also included.

CONCLUSIONS

GCs play key roles in treating severe COVID-19 infections. Pharmacologically, GCs could modulate immune cells, reduce cytokine and chemokine, and improve endothelial functions in patients with severe COVID-19. Benefits of GCs have been observed in multiple clinical trials, but the timing, dosage and duration vary across studies. Tapering as an option is not widely accepted. However, early initiation of treatment, a tailored dosage with appropriate tapering may be of particular importance, but evidence is inconclusive and more investigations are needed. Biological markers, respiratory parameters, and radiological evidence could also help select patients for specific tailored treatments.

Pharmacological principles guiding prolonged glucocorticoid treatment in ARDS

Current literature addressing the pharmacological principles guiding glucocorticoid (GC) administration in ARDS is scant. This paucity of information may have led to the heterogeneity of treatment protocols and misinterpretation of available findings. GCs are agonist compounds that bind to the GC receptor (GR) producing a pharmacological response. Clinical efficacy depends on the magnitude and duration of exposure to GR. We updated the meta-analysis of randomized trials investigating GC treatment in ARDS, focusing on treatment protocols and response. We synthesized the current literature on the role of the GR in GC therapy including genomic and non-genomic effects, and integrated current clinical pharmacology knowledge of various GCs, including hydrocortisone, methylprednisolone and dexamethasone. This review addresses the role dosage, timing of initiation, mode of administration, duration, and tapering play in achieving optimal response to GC therapy in ARDS. Based on RCTs' findings, GC plasma concentration-time profiles, and pharmacodynamic studies, optimal results are most likely achievable with early intervention, an initial bolus dose to achieve close to maximal GRα saturation, followed by a continuous infusion to maintain high levels of response throughout the treatment period. In addition, patients receiving similar GC doses may experience substantial between-patient variability in plasma concentrations affecting clinical response. GC should be dose-adjusted and administered for a duration targeting clinical and laboratory improvement, followed by dose-tapering to achieve gradual recovery of the suppressed hypothalamic-pituitary-adrenal (HPA) axis. These findings have practical clinical relevance. Future RCTs should consider these pharmacological principles in the study design and interpretation of findings.

An Exploratory Reanalysis of the Randomized Trial on Efficacy of Corticosteroids as Rescue Therapy for the Late Phase of Acute Respiratory Distress Syndrome

OBJECTIVES

In the Acute Respiratory Distress Syndrome Network randomized controlled trial, methylprednisolone treatment was associated with increased return to mechanical ventilation with partial loss of early improvements. We hypothesize a causal relationship between protocol-driven rapid discontinuation of methylprednisolone post extubation and return to mechanical ventilation. To explore this possibility, we investigated the timing that events occurred in each treatment arm during active treatment intervention (efficacy) and after stopping therapy.

DESIGN AND SETTINGS

Retrospective intention-to-treat analysis of multicenter randomized controlled trial.

PATIENTS AND INTERVENTIONS

Patients were randomized to methylprednisolone (2 mg/kg/d) or placebo (89 vs 91). The target sample size was reduced post hoc and provided 80% power for an optimistic 50% mortality reduction.

MEASUREMENTS AND MAIN RESULTS

Findings are reported as methylprednisolone versus placebo. By day 28, fewer patients died before achieving extubation (15.7% vs 25.3% and risk ratio, 0.62; 95% CI, 0.34-1.13), more achieved successful extubation (71.9% vs 49.5% and risk ratio, 1.45; CI, 1.14-1.85), time to successful extubation was shorter (hazard ratio, 2.05; CI, 1.42-2.96), and more were discharged alive from the ICU (65.2% vs 48.3%; risk ratio, 1.35; CI, 1.04-1.75). After treatment discontinuation, more methylprednisolone-treated patients returned to mechanical ventilation (26.6% vs 6.7%; risk ratio, 3.98; CI, 1.24-12.79)-consistent with reconstituted systemic inflammation in the presence of adrenal suppression. Participants returning to mechanical ventilation without reinstitution of methylprednisolone had increased risk of ventilator dependence and mortality. Despite loss of early benefits, methylprednisolone was associated with sizable and significant improvements in all secondary outcomes and reduction in serious complications (shock and severe infections).

CONCLUSIONS

During active intervention, methylprednisolone was safe and effective in achieving disease resolution. Our findings support rapid glucocorticoid discontinuation post extubation as likely cause of disease relapse. Gradual tapering might be necessary to preserve the significant improvements achieved during methylprednisolone administration.

Adaptive trials in paediatric development: dealing with heterogeneity and uncertainty in pharmacokinetic differences in children

AIMS

To assess whether an adaptive design in early clinical trials based on the paradigm of variable dosing and controlled exposure can provide better dosing recommendations compared with the standard fixed dose approach.

METHODS

In a clinical trial simulation setting, a paediatric study was simulated using a pharmacokinetic model previously developed for abacavir. Plasma concentrations following the current recommended dose (8 mg kg⁻¹) were taken at standard sampling times, exposures (AUC) were calculated and doses individually adapted to reach the target exposure (i.e. effective exposure in adults). A second round of simulations followed with the adapted doses, and the resulting concentrations were fitted again with the same model. Exposure distributions in both conditions (i.e. fixed dose and controlled exposure) were compared with the target exposure.

RESULTS

The AUC distribution after the current dose resulted in a median exposure of 6.43 mg h l⁻¹ (90th percentile 3.13-10.67 mg h l⁻¹). A total of 61 of 128 subjects showed AUC values either too low or to high compared with the target exposure. After dose adjustment, the median exposure was 6.94 mg h l⁻¹ (5.57-8.25 mg h l⁻¹), and only 14 subjects deviated from the target range.

CONCLUSIONS

Adaptive randomization can be used to optimize dosing regimens in early paediatric clinical trials. The randomization of patients to target exposure rather than dose increases the probability of demonstrating efficacy (i.e. study power) compared with dose-controlled trials. Furthermore, it contributes to further understanding of the role of dose on the total heterogeneity in clinical response.

Corticosteroids and ARDS: A review of treatment and prevention evidence

To systematically review the role of corticosteroids in prevention of acute respiratory distress syndrome (ARDS) in high-risk patients, and in treatment of established ARDS. Primary articles were identified by English-language Pubmed/MEDLINE, Cochrane central register of controlled trials, and Cochrane systemic review database search (1960–June 2009) using the MeSH headings: ARDS, adult respiratory distress syndrome, ARDS, corticosteroids, and methylprednisolone (MP). The identified studies were reviewed and information regarding role of corticosteroids in prevention and treatment of ARDS was evaluated. Nine trials have evaluated the role of corticosteroid drugs in management of ARDS at various stages. Of the 9, 4 trials evaluated role of corticosteroids in prevention of ARDS, while other 5 trials were focused on treatment after variable periods of onset of ARDS. Trials with preventive corticosteroids, mostly using high doses of MP, showed negative results with patients in treatment arm, showing higher mortality and rate of ARDS development. While trials of corticosteroids in early ARDS showed variable results, somewhat, favoring use of these agents to reduce associated morbidities. In late stage of ARDS, these drugs have no benefits and are associated with adverse outcome. Use of corticosteroids in patients with early ARDS showed equivocal results in decreasing mortality; however, there is evidence that these drugs reduce organ dysfunction score, lung injury score, ventilator requirement, and intensive care unit stay. However, most of these trials are small, having a significant heterogeneity regarding study design, etiology of ARDS, and dosage of corticosteroids. Further research involving large-scale trials on relatively homogeneous cohort is necessary to establish the role of corticosteroids for this condition.

Methylprednisolone Infusion in Early Severe ARDS

OBJECTIVE

To determine the effects of low-dose prolonged methylprednisolone infusion on lung function in patients with early severe ARDS.

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

ICUs of five hospitals in Memphis.

PARTICIPANTS

Ninety-one patients with severe early ARDS (</= 72 h), 66% with sepsis.

INTERVENTIONS

Patients were randomized (2:1 fashion) to methylprednisolone infusion (1 mg/kg/d) vs placebo. The duration of treatment was up to 28 days. Infection surveillance and avoidance of paralysis were integral components of the protocol.

MAIN OUTCOME MEASURE

The predefined primary end point was a 1-point reduction in lung injury score (LIS) or successful extubation by day 7.

RESULTS

In intention-to-treat analysis, the response of the two groups (63 treated and 28 control) clearly diverged by day 7, with twice the proportion of treated patients achieving a 1-point reduction in LIS (69.8% vs 35.7%; p = 0.002) and breathing without assistance (53.9% vs 25.0%; p = 0.01). Treated patients had significant reduction in C-reactive protein levels, and by day 7 had lower LIS and multiple organ dysfunction syndrome scores. Treatment was associated with a reduction in the duration of mechanical ventilation (p = 0.002), ICU stay (p = 0.007), and ICU mortality (20.6% vs 42.9%; p = 0.03). Treated patients had a lower rate of infections (p = 0.0002), and infection surveillance identified 56% of nosocomial infections in patients without fever.

CONCLUSIONS

Methylprednisolone-induced down-regulation of systemic inflammation was associated with significant improvement in pulmonary and extrapulmonary organ dysfunction and reduction in duration of mechanical ventilation and ICU length of stay.

Pharmacokinetics and pharmacodynamics of systemically administered glucocorticoids

Glucocorticoids have pleiotropic effects that are used to treat diverse diseases such as asthma, rheumatoid arthritis, systemic lupus erythematosus and acute kidney transplant rejection. The most commonly used systemic glucocorticoids are hydrocortisone, prednisolone, methylprednisolone and dexamethasone. These glucocorticoids have good oral bioavailability and are eliminated mainly by hepatic metabolism and renal excretion of the metabolites. Plasma concentrations follow a biexponential pattern. Two-compartment models are used after intravenous administration, but one-compartment models are sufficient after oral administration.The effects of glucocorticoids are mediated by genomic and possibly nongenomic mechanisms. Genomic mechanisms include activation of the cytosolic glucocorticoid receptor that leads to activation or repression of protein synthesis, including cytokines, chemokines, inflammatory enzymes and adhesion molecules. Thus, inflammation and immune response mechanisms may be modified. Nongenomic mechanisms might play an additional role in glucocorticoid pulse therapy. Clinical efficacy depends on glucocorticoid pharmacokinetics and pharmacodynamics. Pharmacokinetic parameters such as the elimination half-life, and pharmacodynamic parameters such as the concentration producing the half-maximal effect, determine the duration and intensity of glucocorticoid effects. The special contribution of either of these can be distinguished with pharmacokinetic/pharmacodynamic analysis. We performed simulations with a pharmacokinetic/pharmacodynamic model using T helper cell counts and endogenous cortisol as biomarkers for the effects of methylprednisolone. These simulations suggest that the clinical efficacy of low-dose glucocorticoid regimens might be increased with twice-daily glucocorticoid administration.

Models for time-varying covariates in population pharmacokinetic-pharmacodynamic analysis

AIM

If appropriately accounted for in a pharmacokinetic (PK)-pharmacodynamic (PD) model, time-varying covariates can provide additional information to that obtained from time-constant covariates. The aim was to present and apply two models applicable to time-varying covariates that capture such additional information.

METHODS

The first model estimates different covariate-parameter relationships for within- and between-individual variation in covariate values, by splitting the standard covariate model into a baseline covariate (BCOV) effect and a difference from baseline covariate (DCOV) effect. The second model allows the magnitude of the covariate effect to vary between individuals, by inclusion of interindividual variability in the covariate effect. The models were applied to four previously analysed data sets.

RESULTS

The models were applied to 10 covariate-parameter relationships and for three of these the first extended model resulted in a significant improvement of the fit. Even when this model did not improve the fit significantly, it provided useful information because the standard covariate model, which assumes within- and between-patient covariate relationships of the same magnitude, was only supported by the data in four cases. The inclusion of BCOV was not supported in two cases and DCOV was unnecessary in three cases. In one case, significantly different, nonzero, relationships were found for DCOV and BCOV. The second extended model was found to be significant for four of the 10 covariate-parameter relationships.

CONCLUSIONS

On the basis of the examples presented, traditionally made simplifications of covariate-parameter relationships are often inadequate. Extensions to the covariate-parameter relationships that include time-varying covariates have been developed, and their appropriateness and benefits have been described.

Structural determinants of P-glycoprotein-mediated transport of glucocorticoids

PURPOSE

The aim of this study was to determine requisite structural features for P-glycoprotein-mediated transport of a series of structurally related glucocorticoids (GCs).

METHODS

Transport experiments were conducted in wild-type and stably transfected MDRI LLC-PK cell line. Transport efficiency (Teff = Peff, B-->A / Peff, A-->B) in both cell lines was compared as a measure of passive diffusion and P-glycoprotein-mediated transepithelial transport for each steroid. Three-dimensional structure-activity relationships were built to determine how specific structural features within the steroids affect their P-gp-mediated efflux.

RESULTS

Mean (+/- SD) Teff in LLC-PK cells was 1.1 +/- 0.17, indicating that differences in structure and partition coefficient did not affect drug flux in the absence of P-glycoprotein. Teff in L-MDRI cells ranged from 3.6 to 26.6, demonstrating the importance of glucocorticoid structure to P-glycoprotein transport. The rank order of Teff in MDR1 cells was: methylprednisolone> prednisolone > betamethasone > dexamethasone/prednisone > cortisol. There was no correlation between individual Teff values and partition coefficient. 3D-QSAR models were built using CoMFA and CoMSIA with a q2 (r2) of 0.48 (0.99) and 0.41 (0.95), respectively.

CONCLUSIONS

Nonpolar bulky substituents around the C-6alpha position, as well as a hydrogen-bond donor at position C-11, enhance P-glycoprotein affinity and cellular efflux, whereas bulky substituents at C-16 diminish transporter affinity.

Systemic Inflammation-Associated Glucocorticoid Resistance and Outcome of ARDS

Dysregulated systemic inflammation with excess activation of pro-inflammatory transcription factor nuclear factor-kappaB (NF-kappaB)-activated by inflammatory signals-compared to the anti-inflammatory transcription factor glucocorticoid receptor-alpha (GRalpha)-activated by endogenous or exogenous glucocorticoids (GCs)-is an important pathogenetic mechanism for pulmonary and extrapulmonary organ dysfunction in patients with acute respiratory distress syndrome (ARDS). Activation of one transcription factor in excess of the binding (inhibitory) capacity of the other shifts cellular responses toward increased (dysregulated) or decreased (regulated) transcription of inflammatory mediators over time. Recent data indicate that failure to improve in ARDS (unresolving ARDS) is frequently associated with failure of the activated GRs to downregulate the transcription of inflammatory cytokines despite elevated levels of circulating cortisol, a condition defined as systemic inflammation-associated acquired GC resistance; it is potentially reversible with prolonged GC supplementation. In the first part of this paper, after a brief description of inflammation in ARDS and our model of translational research, we review the two cellular signaling pathways that are central to the regulation of inflammation-the stimulatory NF-alphaB and the inhibitory GRalpha. In the second part, we review findings of recent studies indicating that excessive inflammatory activity in patients with unresolving ARDS may induce noncompensated GC resistance in target organs. In the third part, we review factors affecting cellular response to GC and potential mechanisms involved in inflammation-associated GC resistance.