Pharmacokinetic/pharmacodynamic modelling of effects of dexamethasone and prednisolone in combination with endogenous cortisol on lymphocyte counts and systemic markers of bone turn over and inflammation in healthy and asthmatic men

IL-6-induced response of human osteoblasts from patients with rheumatoid arthritis after inhibition of the signaling pathway

Interleukin (IL-) 6 is a critical factor in inflammatory processes of rheumatoid arthritis (RA). This is of high interest as the progression of RA may lead to the implantation of joint endoprostheses, which is associated with a pro-inflammatory increase in IL-6 in the periprosthetic tissue. Biological agents such as sarilumab have been developed to inhibit IL-6-mediated signaling. However, IL-6 signaling blockade should consider the inhibition of inflammatory processes and the regenerative functions of IL-6. This in vitro study investigated whether inhibiting IL-6 receptors can affect the differentiation of osteoblasts isolated from patients with RA. Since wear particles can be generated at the articular surfaces of endoprostheses leading to osteolysis and implant loosening, the potential of sarilumab to inhibit wear particle-induced pro-inflammatory processes should be investigated. Both in monocultures and indirect co-cultures with osteoclast-like cells (OLCs), human osteoblasts were stimulated with 50 ng/mL each of IL-6 + sIL-6R and in combination with sarilumab (250 nM) to characterize cell viability and osteogenic differentiation capacity. Furthermore, the influence of IL-6 + sIL-6R or sarilumab on viability, differentiation, and inflammation was evaluated in osteoblasts exposed to particles. Stimulation with IL-6 + sIL-6R and sarilumab did not affect cell viability. Except for the significant induction of RUNX2 mRNA by IL-6 + sIL-6R and a significant reduction with sarilumab, no effects on cell differentiation and mineralization could be detected. Furthermore, the different stimulations did not affect the osteogenic and osteoclastic differentiation of co-cultured cells. Compared to the osteoblastic monocultures, a decreased release of IL-8 was triggered in the co-culture. Among these, treatment with sarilumab alone resulted in the greatest reduction of IL-8. The co-culture also showed clearly increased OPN concentrations than the respective monocultures, with OPN secretion apparently triggered by the OLCs. Particle exposure demonstrated decreased osteogenic differentiation using different treatment strategies. However, sarilumab administration caused a trend toward a decrease in IL-8 production after stimulation with IL-6 + sIL-6R. The blockade of IL-6 and its pathway have no significant effect on the osteogenic and osteoclastic differentiation of bone cells derived from patients with RA. Nonetheless, observed effects on the reduced IL-8 secretion need further investigation.

Effects of early dexamethasone treatment on several markers of inflammation and fibrosis in an animal model of lung silicosis in rats – A pilot study

Lung silicosis is primarily caused by inhalation of particles of silicon oxide (silica). Despite a huge progress in understanding the interactions among the pathomechanisms of lung silicosis in the last years, there is a lack of effective therapy. With respect to a wide therapeutic action of corticosteroids, the purpose of this pilot study was to evaluate early effects of dexamethasone on several markers of inflammation and lung fibrosis in a rat model of silicosis. The silicosis model was induced by a single transoral intratracheal instillation of silica (50 mg/ml/animal), while the controls received an equivalent volume of sterile saline. The treatment with intraperitoneal dexamethasone initiated the next day after the silica instillation and was given 2-times a week at a dose of 1 mg/kg, while the controls received an equivalent volume of saline. The animals were euthanized 14 or 28 days after the treatment onset. Total and differential counts of leukocytes in the blood and bronchoalveolar lavage (BAL) fluid were determined. The presence of collagen in the bronchioles and lung vessels was detected by Sirius red staining and a smooth muscle mass was detected by smooth muscle actin. In comparison to saline, the instillation of silica increased the total count of circulating leukocytes after 14 and 28 days of the experiment (both p<0.05), which was associated with higher counts of lymphocytes (p<0.05 after 14 days, p>0.05 after 28 days) and slight but non-significant increases in neutrophils and eosinophils (both p>0.05). Although the total cell count in the BAL fluid did not change significantly, the percentages and absolute counts of neutrophils, eosinophils, and lymphocytes (p<0.05, p<0.01 or p<0.001) elevated after 14 and 28 days of the experiment. Silica induced an accumulation of collagen in the bronchioles (p<0.001 after both 14 and 28 days) and pulmonary vessels (p<0.01 after both 14 and 28 days) and elevated a formation of smooth muscle mass (p<0.05 after 14 days, p<0.01 or p<0.001 after 28 days). Treatment with dexamethasone decreased circulating leukocytes (p<0.01) and lymphocytes (p<0.001) and increased neutrophils (p<0.05), which was associated with a slightly decreased total cell count in BAL (p>0.05), decline in lymphocytes (p<0.01), and slight decreases in neutrophils and eosinophils after 28 days of the treatment. Moreover, dexamethasone reduced the accumulation of collagen (p<0.01 after 14 days and p<0.001 after 28 days) and the formation of smooth muscle mass (p<0.01 for bronchioles and p>0.05 for vessels after 24 days, p<0.001 for both bronchioles and vessels after 28 days). In conclusion, early dexamethasone treatment mitigated silica-induced granulocytic-lymphocytic inflammation and decreased a formation of collagen and smooth muscle mass in the bronchiolar and vascular walls, demonstrating a therapeutic potential of dexamethasone in the lung silicosis.

Mortality Risk in Patients With Adrenal Insufficiency Using Prednisolone or Hydrocortisone: A Retrospective Cohort Study

CONTEXT

Prednisolone has been recommended rather than hydrocortisone for glucocorticoid replacement in adrenal insufficiency due its longer duration of action and lower cost.

OBJECTIVE

To determine mortality rates with prednisolone versus hydrocortisone.

METHODS

In this observational study, we used data extracted from a UK primary care database (Clinical Practice Research Datalink) to measure the relative mortality of patients with primary and secondary adrenal insufficiency, who were treated with either prednisolone or hydrocortisone, and control individuals who were individually matched for age, sex, period, and place of follow-up.

RESULTS

As expected, mortality in adrenal insufficiency irrespective of cause was increased, based on 5478 patients (4228 on hydrocortisone; 1250 on prednisolone) and 54 314 controls (41 934 and 12 380, respectively). Overall, the adjusted hazard ratio (HR) was similar with the 2 treatments (prednisolone, 1.76 [95% CI, 1.54-2.01] vs hydrocortisone 1.69 [1.57-1.82]; P = 0.65). This was also the case for secondary adrenal insufficiency. In primary disease (1405 on hydrocortisone vs 137 on prednisolone; 13 965 and 1347 controls, respectively), prednisolone users were older, more likely to have another autoimmune disease and malignancy, and less likely to have mineralocorticoid replacement. Nevertheless, after adjustment, the HR for prednisolone-treated patients remained higher than for those taking hydrocortisone (2.92 [2.19-3.91] vs 1.90 [1.66-2.16]; P = 0.0020).

CONCLUSION

In primary but not in secondary adrenal insufficiency, mortality was higher with prednisolone. The study was large, but the number of prednisolone-treated patients was small, and they had greater risk factors. Nonetheless, the increased mortality associated with prednisolone persisted despite statistical adjustment. Further evidence is needed regarding the long-term safety of prednisolone as routine replacement.

Population pharmacodynamic modeling of intramuscular and oral dexamethasone and betamethasone effects on six biomarkers with circadian complexities in Indian women

Population pharmacokinetic/pharmacodynamic (PK/PD) analysis was performed for extensive data for differing dosage forms and routes for dexamethasone (DEX) and betamethasone (BET) in 48 healthy nonpregnant Indian women in a partial and complex cross-over design. Single doses of 6 mg dexamethasone phosphate (DEX-P), betamethasone phosphate (BET-P), or 1:1 mixture of betamethasone phosphate and acetate (BET-PA) were administered orally (PO) or intramuscularly (IM) where each woman enrolled in a two-period cross-over study. Plasma concentrations collected over 96 h were described with a two-compartment model with differing PO and IM first-order absorption inputs. Overall, BET exhibited slower clearance, similar volume of distribution, faster absorption, and longer persistence than DEX with BET acetate producing extremely slow absorption but full bioavailability of BET. Six biomarkers were assessed over a 24-h baseline period with four showing circadian rhythms with complex baselines. These baselines and the strong responses seen after drug dosing were fitted with various indirect response models using the Laplace estimation methods in NONMEM 7.4. Both the PK and six biomarker responses were well-described with modest variability likely due to the homogeneous ages, weights, and ethnicities of the women. The drugs either inhibited or stimulated the influx processes with some models requiring joint inclusion of drug effects on circadian cortisol suppression. The biomarkers and order of sensitivity (lowest IC₅₀/SC₅₀ to highest) were: cortisol, T-helper cells, basophils, glucose, neutrophils, and T-cytotoxic cells. DEX sensitivities were generally greater than BET with corresponding mean ratios for these biomarkers of 2.86, 1.27, 1.72, 1.27, 2.69, and 1.06. Overall, the longer PK (e.g. half-life) of BET, but lesser PD activity (e.g. higher IC₅₀), produces single-dose response profiles that appear quite similar, except for the extended effects from BET-PA. This comprehensive population modeling effort provides the first detailed comparison of the PK profiles and six biomarker responses of five commonly used dosage forms of DEX and BET in healthy women.

Procaterol but not dexamethasone protects 16HBE cells from H₂O₂-induced oxidative stress

Oxidative stress is an important pathophysiological factor of asthma and chronic obstructive pulmonary disease (COPD). We hypothesized that procaterol and dexamethasone might treat inflammation through inhibiting oxidative stress in vitro. This study evaluated procaterol and dexamethasone in the hydrogen peroxide (H2O2)-induced immortal human bronchial epithelial cell model of oxidative stress and investigated the underlying mechanisms. Results showed that exposure to 125 μM H2O2 for 2 h led to a 50% reduction in the cell viability, significantly increased the percentage of apoptosis, and elevated levels of malondialdehyde and reactive oxygen species. Pretreatment with procaterol (25 - 200 nM) could reduce these effects in a dose-dependent manner. In contrast, pretreatment with dexamethasone (100 nM, 1000 nM) was inefficient. Pretreatment with procaterol plus dexamethasone (100 nM procaterol + 1000 nM dexamethasone) was effective, but the combined effect was not more effective than the sole pretreatment with 100 nM procaterol. The nuclear factor kappa-B (NF-κB) pathway was involved in the pathogenic mechanisms of H2O2. Procaterol may indirectly inhibit H2O2-induced activation of the NF-κB pathway due to its capability of antioxidation. Glucocorticoids may be not recommended to treat asthma or COPD complicated with severe oxidative stress.

A physiologically based pharmacokinetics model for melatonin--effects of light and routes of administration

Physiologically based pharmacokinetic (PBPK) models were developed using MATLAB Simulink(®) to predict diurnal variations of endogenous melatonin with light as well as pharmacokinetics of exogenous melatonin via different routes of administration. The model was structured using whole body, including pineal and saliva compartments, and parameterized based on the literature values for endogenous melatonin. It was then optimized by including various intensities of light and various dosage and formulation of melatonin. The model predictions generally have a good fit with available experimental data as evaluated by mean squared errors and ratios between model-predicted and observed values considering large variations in melatonin secretion and pharmacokinetics as reported in the literature. It also demonstrates the capability and usefulness in simulating plasma and salivary concentrations of melatonin under different light conditions and the interaction of endogenous melatonin with the pharmacokinetics of exogenous melatonin. Given the mechanistic approach and programming flexibility of MATLAB Simulink(®), the PBPK model could provide predictions of endogenous melatonin rhythms and pharmacokinetic changes in response to environmental (light) and experimental (dosage and route of administration) conditions. Furthermore, the model may be used to optimize the combined treatment using light exposure and exogenous melatonin for maximal phase advances or delays.

Synergistic stimulation of myogenesis by glucocorticoid and IGF-I signaling

Muscle wasting is associated with poor prognosis in chronic obstructive pulmonary disease (COPD). Exercise stimulates muscle recovery, but its efficacy is variable, depending on the clinical condition and medical treatment. Systemic glucocorticoids, commonly administered in high doses during acute disease exacerbations or as maintenance treatment in end-stage disease, are known to contribute to muscle wasting. As muscle mass recovery involves insulin-like growth factor (IGF)-I signaling, which can be stimulated by anabolic steroids, the impact of glucocorticoids and the effect of simultaneous IGF-I stimulation by anabolic steroids on muscle recovery and growth were investigated. The effects of, and interactions between, glucocorticoid and IGF-I signaling on skeletal muscle growth were assessed in differentiating C2C12 myocytes. As proof of principle, we performed a post hoc analysis stratifying patients by glucocorticoid use of a clinical trial investigating the efficacy of anabolic steroid supplementation on muscle recovery in muscle-wasted patients with COPD. Glucocorticoids strongly impaired protein synthesis signaling, myotube formation, and muscle-specific protein expression. In contrast, in the presence of glucocorticoids, IGF-I synergistically stimulated myotube fusion and myofibrillar protein expression, which corresponded with restored protein synthesis signaling by IGF-I and increased transcriptional activation of muscle-specific genes by glucocorticoids. In COPD patients on maintenance glucocorticoid treatment, the clinical trial also revealed an enhanced effect of anabolic steroids on muscle mass and respiratory muscle strength. In conclusion, synergistic effects of anabolic steroids and glucocorticoids on muscle recovery may be caused by relief of the glucocorticoid-imposed blockade on protein synthesis signaling, allowing effective translation of glucocorticoid-induced accumulation of muscle-specific gene transcripts.

A Pilot Study Comparing the Diabetogenic Effects of Dexamethasone and Prednisolone in Cats

Fourteen cats received either daily prednisolone (4.4 mg/kg per os [PO]) or dexamethasone (0.55 mg/kg PO) for 56 days. These doses were clinically equipotent. Serum fructosamine and urine glucose were measured on days 0, 28, and 56. Insulin sensitivity, glucose tolerance, and peak insulin secretion were measured in each group prior to and at the end of the courses of glucocorticoid administration. On day 56, the prevalence of glucosuria was significantly greater (P=0.027), and a trend was seen toward greater fructosamine concentrations (P=0.083) in dexamethasone-treated cats compared to prednisolone-treated cats. The results of this pilot study also showed a trend toward a greater decrease in insulin sensitivity (P=0.061) and a significantly lower compensatory increase in insulin secretion (P=0.081) in the dexamethasone-treated cats than in cats administered prednisolone. These preliminary data suggest that dexamethasone exhibits greater diabetogenic effects in cats than equipotent doses of prednisolone. Further study is justified to support this hypothesis.

Inadequacies of glucocorticoid replacement and improvements by physiological circadian therapy

Patients with adrenal insufficiency need lifelong glucocorticoid replacement, but many suffer from poor quality of life, and overall there is increased mortality. Moreover, it appears that use of glucocorticoids at the higher end of the replacement dose range is associated with increased risk for cardiovascular and metabolic bone disease. These data highlight some of the inadequacies of current regimes. The cortisol production rate is estimated to be equivalent to 5.7-7.4 mg/m(2) per day, and a major difficulty for replacement regimes is the inability to match the distinct circadian rhythm of circulating cortisol levels, which are low at the time of sleep onset, rise between 0200 and 0400 h, peaking just after waking and then fall during the day. Another issue is that current dose equivalents of glucocorticoids used for replacement are based on anti-inflammatory potency, and few data exist as to doses needed for equivalent cardiovascular and bone effects. Weight-adjusted, thrice-daily dosing using hydrocortisone (HC) reduces glucocorticoid overexposure and represents the most refined regime for current oral therapy, but does not replicate the normal cortisol rhythm. Recently, proof-of-concept studies have shown that more physiological circadian glucocorticoid therapy using HC infusions and newly developed oral formulations of HC have the potential for better biochemical control in patients with adrenal insufficiency. Whether such physiological replacement will have an impact on the complications seen in patients with adrenal insufficiency will need to be analysed in future clinical trials.

Deflazacort: a glucocorticoid with few metabolic adverse effects but important immunosuppressive activity

Deflazacort (DFZ) is a synthetic glucocorticoid that has few adverse effects on glucose and calcium metabolism and fewer deleterious effects on the neuronal population. Therefore, it may have a crucial role in the treatment of patients with autoimmune disorders associated with central nervous system or metabolic affectations. To date, the pharmacologic safety profile of DFZ is considered similar to that of other glucocorticoids. Nevertheless, cumulative clinical and laboratory evidence suggests that DFZ has, in fact, greater immunosuppressive activity than was previously thought. Therefore, it is possible that DFZ increases the risk of acquiring opportunistic infection compared with other synthetic glucocorticoids. Additional pharmacologic studies are needed to fully establish the immunosuppressive potency of DFZ and, consequently, to determine the appropriate ratio of bioequivalence in humans.

Systemic corticosteroid therapy for acute asthma exacerbations

Acute exacerbations of asthma may represent reactions to airway irritants or failures of chronic treatment. The costs to both the patient and society are high. Exacerbations often are frightening episodes that can cause significant morbidity and sometimes death. The emergency department (ED) visits and hospitalizations often required lead to significant health care expenses. Thus, preventing and optimizing management of acute exacerbations is critical. Corticosteroids are a cornerstone of asthma therapy. They have been shown to lower admission rates and reduce risk of relapse. This article provides an overview of the role of corticosteroids (including betamethasone, dexamethasone, methylprednisolone, and prednisolone) in the management of acute asthma exacerbations, with an aim toward effective decision making about the choice of therapy.