Physiologically Based Pharmacokinetic Modeling: The Reversible Metabolism and Tissue-Specific Partitioning of Methylprednisolone and Methylprednisone in Rats.

The pharmacokinetics (PK) of methylprednisolone (MPL) exhibited tissue-specific saturable binding and reversible conversion with its metabolite, methylprednisone (MPN). Blood and 11 tissues were collected in male rats after intravenous (i.v.) bolus doses of 50 mg/kg MPL and 20 mg/kg MPN and upon i.v. infusion of MPL and MPN at 0.3, 3, and 10 mg/h per kg. The concentrations of MPL and MPN were simultaneously measured. A comprehensive physiologically based pharmacokinetic (PBPK) model was applied to describe the plasma and tissue profiles and estimate PK parameters of the MPL/MPN interconversion system. Both dosed and formed MPL and MPN were in rapid equilibrium or achieved steady-state rapidly in plasma and tissues. MPL tissue partitioning was nonlinear, with highest capacity in liver (322.9 ng/ml) followed by kidney, heart, intestine, skin, spleen, bone, brain, muscle, and lowest in adipose (2.74 ng/ml) and displaying high penetration in lung. The tissue partition coefficient of MPN was linear but widely variable (0.15∼5.38) across most tissues, with nonlinear binding in liver and kidney. The conversion of MPL to MPN occurred in kidney, lung, and intestine with total clearance of 429 ml/h, and the back conversion occurred in liver and kidney at 1342 ml/h. The irreversible elimination clearance of MPL was 789 ml/h from liver and that of MPN was 2758 ml/h with liver accounting for 44%, lung 35%, and kidney 21%. The reversible metabolism elevated MPL exposure in rats by 13%. This highly complex PBPK model provided unique and comprehensive insights into the disposition of a major corticosteroid. SIGNIFICANCE STATEMENT: Our dual physiologically based pharmacokinetic (PBPK) study and model of methylprednisolone/methylprednisone (MPL/MPN) with multiple complexities reasonably characterized and parameterized their disposition, and provided greater insights into the interpretation of their pharmacodynamics in rats. Drug knowledge gained in this study may be translatable to higher-order species to appreciate the clinical utility of MPL. The complex model itself is instructive for advanced PBPK analysis of drugs with reversible metabolism and/or nonlinear tissue partitioning features.

Pharmacokinetics and bioequivalence of two methylprednisolone tablet formulations in healthy Chinese subjects under fasting and fed conditions.

AIMS: The aims of this study were to evaluate and compare the pharmacokinetic profiles and bioequivalence of two tablet formulations of methylprednisolone (test formulation: Zhejiang Xianju Pharmaceutical Co., Ltd., China; reference formulation: Medrol, Pfizer Italia SRL) in healthy Chinese subjects under fasting and fed conditions. MATERIALS AND METHODS: Subjects were randomly allocated to either the fasting group or the fed group and also to one of two sequences (test-reference or reference-test), according to which they received a single 16-mg dose of the test or reference methylprednisolone tablet in the study periods. Blood samples were collected pre dose and at intervals up to 16 hours after administration. Plasma methylprednisolone concentrations were determined using a validated liquid chromatography tandem mass spectrometry method. The safety of the medications was monitored throughout the study. The primary pharmacokinetic parameters measured were Cmax, AUC0-t, and AUC0-∞. RESULTS: A total of 56 subjects were enrolled, and all completed the study. The 90% confidence intervals for Cmax, AUC0-t, and AUC0-∞, measured under both fasting and fed conditions, fell within the acceptable range for bioequivalence of 80 - 125%. Analysis of variance showed that there were no significant differences in the primary pharmacokinetic parameters (Cmax, AUC0-t, and AUC0-∞) between the test and reference formulation measured under both fasted and fed conditions. No serious or unexpected adverse drug reactions occurred during the study period. CONCLUSION: The test methylprednisolone 16 mg tablet produced in China is bioequivalent to the reference formulation (Medrol) in healthy Chinese subjects measured under both fasting and fed conditions. Both formulations were well tolerated by all study participants.

Polydopamine-Decorated Microcomposites Promote Functional Recovery of an Injured Spinal Cord by Inhibiting Neuroinflammation.

Neuroinflammation following spinal cord injury usually aggravates spinal cord damage. Many inflammatory cytokines are key players in neuroinflammation. Owing largely to the multiplicity of cytokine targets and the complexity of cytokine interactions, it is insufficient to suppress spinal cord damage progression by regulating only one or a few cytokines. Herein, we propose a two-pronged strategy to simultaneously capture the released cytokines and inhibit the synthesis of new ones in a broad-spectrum manner. To achieve this strategy, we designed a core/shell-structured microcomposite, which was composed of a methylprednisolone-incorporated polymer inner core and a biocompatible polydopamine outer shell. Thanks to the inherent adhesive nature of polydopamine, the obtained microcomposite (MP-PLGA@PDA) efficiently neutralized the excessive cytokines in a broad-spectrum manner within 1 day after spinal cord injury. Meanwhile, the controlled release of immunosuppressive methylprednisolone reduced the secretion of new inflammatory cytokines. Benefiting from its efficient and broad-spectrum capability in reducing the level of cytokines, this core/shell-structured microcomposite suppressed the recruitment of macrophages and protected the injured spinal cord, leading to an improved recovery of motor function. Overall, the designed microcomposite successfully achieved the two-pronged strategy in cytokine neutralization, providing an alternative approach to inhibit neuroinflammation in the injured spinal cord.

A preliminary study on urinary excretion patterns of methylprednisolone after oral and intra-articular administration and effect on endogenous glucocorticosteroids profile.

INTRODUCTION: The use of glucocorticosteroids (GCs) through oral, intravenous, intramuscular, or rectal routes is prohibited in sports. Its use is permitted through inhalation, topical and intra-articular route of administration. Methylprednisolone (MP) is available for use by different routes for anti-inflammatory and immunosuppressive purposes. To discriminate its intake by permitted & forbidden routes, a reporting level of 30 ng/ml is set by World Anti-Doping Agency. The aim of this study was to compare MP's excretion profile following oral & intra-articular administration & to evaluate its effect on endogenous GCs profile. MATERIALS & METHODS: The MP was administered through oral and intra-articular route to different patients & urine samples were collected up to 100 h. The urine samples were hydrolyzed, extracted, and analyzed on Liquid chromatography-mass spectrometry/MS. RESULTS: MP levels in urine exceeded the reporting limit of 30 ng/ml after oral (8 mg) and intra-articular administration (80 mg) routes. After oral intake (8 mg), MP levels exceeded the reporting level up to 24 h. However, after intra-articular injection (80 mg), the MP could be detected above the reporting level up to 80 h. CONCLUSION: The findings reveal that the MP can exceed the reporting level in urine even after administration by permitted route (i.a.). Further analysis of four endogenous GCs (Cortisol, Cortisone, TH Cortisone, and 11-deoxycortisol) showed a decreased excretion following administration of MP by oral & intra-articular routes.

Design, Synthesis, and Renal Targeting of Methylprednisolone-Lysozyme.

Methylprednisolone (MP) is often used in the treatment of various kidney diseases, but overcoming the systemic side effects caused by its nonspecific distribution in the body is a challenge. This article reports the design, synthesis, and renal targeting of methylprednisolone-lysozyme (MPS-LZM). This conjugate was obtained by covalently linking MP with the renal targeting carrier LZM through a linker containing an ester bond, which could utilize the renal targeting of LZM to deliver MP to renal proximal tubular epithelial cells and effectively release MP. The reaction conditions for the preparation of the conjugate were mild, and the quality was controllable. The number of drug payloads per LZM was 1.1. Cell-level studies have demonstrated the safety and endocytosis of the conjugate. Further pharmacokinetic experiments confirmed that, compared with that of free MP, the conjugate increased the renal exposure (AUC0-t) of active MP from 17.59 to 242.18 h*ng/mL, and the targeting efficiency improved by approximately 14 times. Tissue and organ imaging further revealed that the conjugate could reach the kidneys quickly, and fluorescence could be detected in the kidneys for up to 12 h. This study preliminarily validates the feasibility of a renal targeting design strategy for MPS-LZM, which is expected to provide a new option for improving kidney-specific distribution of glucocorticoids.

Population Pharmacokinetic/Pharmacodynamic Modeling of Methylprednisolone in Neonates Undergoing Cardiopulmonary Bypass.

Methylprednisolone is used in neonates to modulate cardiopulmonary bypass (CPB)-induced inflammation, but optimal dosing and exposure are unknown. We used plasma methylprednisolone and interleukin (IL)-6 and IL-10 concentrations from neonates enrolled in a randomized trial comparing one vs. two doses of methylprednisolone to develop indirect response population pharmacokinetic/pharmacodynamic models characterizing the exposure-response relationships. We applied the models to simulate methylprednisolone dosages resulting in the desired IL-6 and -10 exposures, known mediators of CPB-induced inflammation. A total of 64 neonates (median weight 3.2 kg, range 2.2-4.3) contributed 290 plasma methylprednisolone concentrations (range 1.07-12,700 ng/mL) and IL-6 (0-681 pg/mL) and IL-10 (0.1-1125 pg/mL). Methylprednisolone plasma exposure following a single 10 mg/kg intravenous dose inhibited IL-6 and stimulated IL-10 production when compared with placebo. Higher (30 mg/kg) or more frequent (twice) dosing did not confer additional benefit. Clinical efficacy studies are needed to evaluate the effect of optimized dosing on outcomes.

Modeling Corticosteroid Pharmacokinetics and Pharmacodynamics, Part II: Sex Differences in Methylprednisolone Pharmacokinetics and Corticosterone Suppression.

Methylprednisolone (MPL), a corticosteroid of intermediate potency, remains an important immunomodulatory agent for autoimmune diseases. Although sex differences in corticosteroid pharmacokinetics/pharmacodynamics (PK/PD) have been documented in humans, comprehensive preclinical assessments of such differences have not been conducted. Limited in vitro evidence indicates possible sex differences in corticosteroid PK and PD. Therefore, it is hypothesized that comparative PK/PD assessments of MPL disposition and selected PD actions in both sexes will provide insights into factors controlling sex differences in steroid responses. This report focused on the plasma and tissue pharmacokinetics of MPL and its adrenal suppressive effects. Because time-dependent (estrous) regulation of sex hormones in females can influence drug responses, female rats were studied in the proestrus (high estradiol/progesterone) and estrus (low estradiol/progesterone) phases of the reproductive cycle. Cohorts of male and female rats were given a 50 mg/kg bolus dose of MPL intramuscularly. Plasma and liver concentrations of MPL as well as plasma corticosterone concentrations were assayed using high-performance liquid chromatography. An enhanced minimal physiologically-based PK/PD model was developed to characterize MPL kinetics and corticosterone dynamics. The clearance of MPL was ∼3-fold higher in males compared with females, regardless of estrous phase, likely attributable to sex-specific hepatic metabolism in males. Strong inhibitory effects on adrenal suppression were observed in all animals. These temporal steroid profiles in plasma and tissues will be used to drive receptor/gene-mediated PD effects of MPL in both sexes, as described in a companion article (Part III). SIGNIFICANCE STATEMENT: Sex is a relevant factor influencing the pharmacokinetics (PK) and pharmacodynamics (PD) of drugs. Few preclinical PK/PD studies, however, include sex as a variable. Sex differences in the PK and adrenal suppressive effects of the synthetic corticosteroid, methylprednisolone, were assessed in male and female rats as a function of the 4-day rodent reproductive cycle. Drug exposure was 3-fold higher in females, regardless of estrous stage, compared with males. An extended minimal physiologically-based PK/PD model utilizing in vitro and in vivo measurements was developed and applied. These studies provide a framework to account for sex-dependent variability in drug and endogenous agonist (corticosterone) exposures, serving as a prelude to more intricate assessments of sex-related variability in receptor/gene-mediated PD corticosteroid actions.

Modeling Corticosteroid Pharmacokinetics and Pharmacodynamics, Part I: Determination and Prediction of Dexamethasone and Methylprednisolone Tissue Binding in the Rat.

The plasma and tissue binding properties of two corticosteroids, dexamethasone (DEX) and methylprednisolone (MPL), were assessed in the rat in anticipation of developing physiologically based pharmacokinetic and pharmacokinetic/pharmacodynamic models. The tissue-to-plasma partition coefficients (K P) of DEX and MPL were measured in liver, muscle, and lung in vivo after steady-state infusion and bolus injection in rats. Since K P is often governed by reversible binding to macromolecules in blood and tissue, an attempt was made to assess K P values of DEX and MPL by in vitro binding studies using rat tissue homogenates and to compare these estimates to those obtained from in vivo kinetics after dosing. The K P values of both steroids were also calculated in rat tissues using mechanistic tissue composition-based equations. The plasma binding of DEX and MPL was linear with moderate binding (60.5% and 82.5%) in male and female rats. In vivo estimates of steroid uptake appeared linear across the tested concentrations and K P was highest in liver and lowest in muscle for both steroids. Assessment of hepatic binding of MPL in vitro was severely affected by drug loss at 37°C in male liver homogenates, whereas DEX was stable in both male and female liver homogenates. With the exception of MPL in liver, in vitro-derived K P estimates reasonably agreed with in vivo values. The mechanistic equations modestly underpredicted K P for both drugs. Tissue metabolism, saturable tissue binding, and active uptake are possible factors that can complicate assessments of in vivo tissue binding of steroids when using tissue homogenates. SIGNIFICANCE STATEMENT: Assuming the free hormone hypothesis, the ratio of the unbound drug fraction in plasma and in tissues defines the tissue-to-plasma partition coefficient (K P), an important parameter in physiologically based pharmacokinetic modeling that determines total drug concentrations within tissues and the steady-state volume of distribution. This study assessed the plasma and tissue binding properties of the synthetic corticosteroids, dexamethasone and methylprednisolone, in rats using ultrafiltration and tissue homogenate techniques. In vitro-in vivo and in silico-in vivo extrapolation of K P was assessed for both drugs in liver, muscle, and lung. Although the extrapolation was fairly successful across the tissues, in vitro homogenate studies severely underpredicted the K P of methylprednisolone in liver, partly attributable to the extensive hepatic metabolism.

Modeling Corticosteroid Pharmacokinetics and Pharmacodynamics, Part III: Estrous Cycle and Estrogen Receptor-Dependent Antagonism of Glucocorticoid-Induced Leucine Zipper (GILZ) Enhancement by Corticosteroids.

Our previous report examined the pharmacokinetics (PK) of methylprednisolone (MPL) and adrenal suppression after a 50 mg/kg IM bolus in male and female rats, and we described in detail the development of a minimal physiologically based pharmacokinetic/pharmacodynamic (mPBPK/PD) model. In continuation of such assessments, we investigated sex differences in genomic MPL responses (PD). Message expression of the glucocorticoid-induced leucine zipper (GILZ) was chosen as a multitissue biomarker of glucocorticoid receptor (GR)-mediated drug response. Potential time-dependent interplay between sex hormone and glucocorticoid signaling in vivo was assessed by comparing the enhancement of GILZ by MPL in the uterus [high estrogen receptor (ER) density] and in liver (lower ER density) from male and female rats dosed within the proestrus (high estradiol/progesterone) and estrus (low estradiol/progesterone) phases of the rodent estrous cycle. An expanded-systems PD model of MPL considering circadian rhythms, multireceptor (ER and GR) control, and estrous variations delineated the determinants controlling receptor/gene-mediated steroid responses. Hepatic GILZ response was ∼3-fold greater in females, regardless of estrous stage, compared with males, driven predominantly by increased MPL exposure in females and a negligible influence of estrogen interaction. In contrast, GILZ response in the uterus during proestrus in females was 60% of that observed in estrus-phased females, despite no PK or receptor differences, providing in vivo support to the hypothesis of estrogen-mediated antagonism of glucocorticoid signaling. The developed model offers a mechanistic platform to assess the determinants of sex and tissue specificity in corticosteroid actions and, in turn, reveals a unique PD drug-hormone interaction occurring in vivo. SIGNIFICANCE STATEMENT: Mechanisms relating to sex-based pharmacodynamic variability in genomic responses to corticosteroids have been unclear. Using combined experimental and systems pharmacology modeling approaches, sex differences in both pharmacokinetic and pharmacodynamic mechanisms controlling the enhancement of a sensitive corticosteroid-regulated biomarker, the glucocorticoid-induced leucine zipper (GILZ), were clarified in vivo. The multiscale minimal physiologically based pharmacokinetics/pharmacodynamic model successfully captured the experimental observations and quantitatively discerned the roles of the rodent estrous cycle (hormonal variation) and tissue specificity in mediating the antagonistic coregulation of GILZ gene synthesis. These findings collectively support the hypothesis that estrogens antagonize pharmacodynamic signaling of genomic corticosteroid actions in vivo in a time- and estrogen receptor-dependent manner.

Biorelevant release testing of biodegradable microspheres intended for intra-articular administration.

Characterization of controlled release formulations used for intra-articular (IA) drug administration is challenging. Bio-relevant synovial fluids (BSF), containing physiologically relevant amounts of hyaluronic acid, phospholipids and proteins, were recently proposed to simulate healthy and osteoarthritic conditions. This work aims to evaluate the performance of different controlled release formulations of methylprednisolone (MP) for IA administration, under healthy and disease states simulated conditions. Microspheres differed in grade of poly(lactide-co-glycolide) and in the theoretical drug content (i.e. 23 or 30% w/w). Their performance was compared with the commercially available suspension of MP acetate (MPA). Under osteoarthritic state simulated condition, proteins increased the MPA release and reduced the MPA hydrolysis rate, over 48 h. Regarding microspheres, the release patterns over 40 days were significantly influenced by the composition of BSF. The pattern of the release mechanism and the amount released was affected by the presence of proteins. Protein concentration affected the release and the concentration used is critical, particularly given the relevance of the concentrations to target patient populations, i.e. patients with osteoarthritis.

Variability in plasma concentrations of methylprednisolone 6 days after intrasynovial injection of methylprednisolone acetate in racing horses: A field study.

BACKGROUND: Methylprednisolone (MP) acetate is a commonly used corticosteroid for suppression of inflammation in synovial structures in horses. Its use is often regulated in equine sports by plasma MP concentrations. OBJECTIVES: To describe variability in MP plasma concentrations after MP acetate injection in different synovial structures and with co-administration with hyaluronic acid (HA). STUDY DESIGN: Field study in actively racing horses in three disciplines (Thoroughbred, Standardbred and Quarter Horse). METHODS: Seventy-six horses (15 Thoroughbreds, 20 Standardbreds and 41 Quarter Horses) were included in the study. Injection of any synovial structure with a total body dose of 100 mg MP acetate was permitted, data were grouped according to the synovial structure injected and co-administration with HA. Plasma was collected before injection and at 6 days post-injection. Per cent censored data (below the limit of quantification) for each synovial structure were determined, and summary statistics generated by Robust Regression on Order. Differences between synovial structures and co-administration with HA were identified by ANOVA with Tukey's post hoc testing. RESULTS: The MP plasma concentration at 6 days for injection for the entire group (mean ± standard deviation [s.d.], pg/mL) was 96 ± 104. Metacarpophalangeal (MCP) plasma concentrations contained 86% censored data and could not be included in the statistical analysis. The carpal joints (CJO) group had a lower plasma MP concentration (P<0.05) than the distal tarsal joints (DTJ) or medial femorotibial (MFT), the no HA (NHA) group had a lower plasma MP concentration (P<0.05) than HA. MAIN LIMITATIONS: The synovial structures injected varied by racing discipline, so this study was unable to identify any differences between disciplines. CONCLUSIONS: Practitioners should be aware that injection of DTJ, CS and MFT joints, and combining MP acetate with HA may prolong its clearance, and withdrawal times for competition in regulated equine sports.

Granulocyte Colony-Stimulating Factor Combined with Methylprednisolone Improves Functional Outcomes in Rats with Experimental Acute Spinal Cord Injury.

OBJECTIVES: To evaluate the effects of combined treatment with granulocyte colony-stimulating factor (G-CSF) and methylprednisolone in rats subjected to experimental spinal cord injury. METHODS: Forty Wistar rats received a moderate spinal cord injury and were divided into four groups: control (no treatment); G-CSF (G-CSF at the time of injury and daily over the next five days); methylprednisolone (methylprednisolone for 24 h); and G-CSF/Methylprednisolone (methylprednisolone for 24 h and G-CSF at the time of injury and daily over the next five days). Functional evaluation was performed using the Basso, Beattie and Bresnahan score on days 2, 7, 14, 21, 28, 35 and 42 following injury. Motor-evoked potentials were evaluated. Histological examination of the spinal cord lesion was performed immediately after euthanasia on day 42. RESULTS: Eight animals were excluded (2 from each group) due to infection, a normal Basso, Beattie and Bresnahan score at their first evaluation, or autophagy, and 32 were evaluated. The combination of methylprednisolone and G-CSF promoted greater functional improvement than methylprednisolone or G-CSF alone (p<0.001). This combination also exhibited a synergistic effect, with improvements in hyperemia and cellular infiltration at the injury site (p<0.001). The groups displayed no neurophysiological differences (latency p=0.85; amplitude p=0.75). CONCLUSION: Methylprednisolone plus G-CSF promotes functional and histological improvements superior to those achieved by either of these drugs alone when treating spinal cord contusion injuries in rats. Combining the two drugs did have a synergistic effect.

Glutathione-PEGylated liposomal methylprednisolone in comparison to free methylprednisolone: slow release characteristics and prolonged lymphocyte depression in a first-in-human study.

AIMS: Intravenous high-dose free methylprednisolone (MP) hemisuccinate is the primary treatment for an acute relapse in relapsing-remitting multiple sclerosis. However, it is inconvenient and its side effects are undesirable. Both dose and dosing frequency can be reduced by incorporating free MP in glutathione-PEGylated liposomes, creating a slow-release formulation with reduced toxicity and prolonged peripheral efficacy. This first-in-human study was designed to assess the safety, pharmacokinetics and pharmacodynamics of glutathione-PEGylated liposomes containing MP (2B3-201). METHODS: The first part was a double-blind, three-way cross over study in 18 healthy male subjects, receiving ascending doses of 2B3-201, active comparator (free MP) or placebo. Part 2 of the study was an open-label infusion of 2B3-201 (different doses), exploring pretreatment with antihistamines and different infusion schedules in another 18 healthy male subjects, and a cross-over study in six healthy female subjects. MP plasma concentrations, lymphocyte counts, adrenocorticotropic hormone, osteocalcin and fasting glucose were determined. Safety and tolerability profiles were assessed based on adverse events, safety measurements and central nervous system tests. RESULTS: The most frequent recorded AE related to 2B3-201 was an infusion related reaction (89%). 2B3-201 was shown to have a plasma half-life between 24 and 37 h and caused a prolonged decrease in the lymphocyte count, adrenocorticotropic hormone and osteocalcin, and a rise in fasting glucose. CONCLUSION: 2B3-201 is considered safe, with no clinically relevant changes in central nervous system safety parameters and no serious adverse events. In addition, 2B3-201 shows a long plasma half-life and prolonged immunosuppressive effects.

Delayed logistic indirect response models: realization of oscillating behavior.

Indirect response (IDR) models are probably the most frequently applied tools relating the effect of a signal to a baseline response. A response modeled by such a classical IDR model will always return monotonously to its baseline after drug administration. We extend IDR models with a delay process, i.e. a retarded response state, that leads to oscillating response behavior. First, IDR models with a first-order production and second-order loss term based on the famous logistic equation are constructed. Second, a delay process similar to the delayed logistic equation is included. Relations of the classical IDR model with our extended IDR model concerning response and model parameters are revealed. Simulations of typical response profiles are presented and data fitting of a model for leptin and cholesterol dynamics after administration of methylprednisolone is performed. The influence of the delay parameter on the other model parameters is discussed.

Randomized phase 2 therapeutic equivalence study of abiraterone acetate fine particle formulation vs. originator abiraterone acetate in patients with metastatic castration-resistant prostate cancer: The STAAR study.

BACKGROUND: This multicenter, randomized, open-label, active-controlled study evaluated therapeutic equivalence, steady-state pharmacokinetics, and safety of a novel abiraterone acetate fine particle formulation (AAFP) 500mg plus methylprednisolone vs. the originator AA (OAA) 1000mg plus prednisone in men with metastatic castrate-resistant prostate cancer (mCRPC). The primary endpoint was a comparison of average of serum testosterone levels on treatment days 9 and 10 between groups. METHODS: Men with progressive mCRPC, receiving gonadotropin-releasing hormone agonist or antagonist therapy, and with a serum testosterone level of <50ng/dl were randomized 1:1 to either AAFP 500mg daily plus 4mg methylprednisolone orally twice daily (BID), or OAA 1000mg daily plus 5mg prednisone BID for 84 days. Serum testosterone, serum prostate-specific antigen (PSA), steady-state (trough) abiraterone pharmacokinetics, and safety were evaluated. RESULTS: Fifty-three patients were enrolled (n = 24, AAFP; n = 29, OAA). Mean age was 75.1 years and 54.7% had Gleason>7. Over 90% of patients in each group achieved absolute testosterone levels of ≤1ng/dl during the study. The averaged absolute testosterone levels ≤0.1ng/dl were achieved in 25% of AAFP-treated patients and 17% of OAA-treated patients. A PSA-50 response was observed in>65% of patients in both groups on days 28, 56, and 84 (P = NS, all timepoints). Days 9 and 10 averaged rounded-up least squares (LS) mean (SE) serum testosterone levels were comparable (1.05ng/dl [0.04], AAFP; 1.02ng/dl [0.03], OAA; P = 0.4703 for LS mean difference). The geometric mean ratio between groups was 1.021 (90% CI: 0.965-1.081); the 90% CI fell within 80.0% to 125.0% equivalence limits. The LS mean differences in abiraterone trough plasma concentrations were not statistically significant at any visit. Adverse event frequency was comparable between arms (75.0%, AAFP; 82.8%, OAA). Musculoskeletal events were more common among OAA-treated patients (37.9% vs. 12.5%). CONCLUSION: Therapeutic equivalence between AAFP 500mg daily and OAA 1000mg daily based on serum testosterone levels was confirmed in mCRPC patients. Both agents led to similar PSA-50 response rates. Abiraterone trough levels were similar between treatments. No new safety concerns were observed.

Assessment of drug-drug interactions between voriconazole and glucocorticoids.

Voriconazole is used to treat fungal infections in patients receiving glucocorticoid therapy in clinic. The objective of this study was to characterize the potential drug-drug interactions (DDIs) between voriconazole and glucocorticoids using physiologically based pharmacokinetic (PBPK) models. Voriconazole and glucocorticoids PBPK models were constructed by using physicochemical data and pharmacokinetic parameters in healthy subjects, and verified by comparing the predicted pharmacokinetic parameters with corresponding data acquired from published literatures. The refined PBPK models were employed to predict the potential DDIs between voriconazole and glucocorticoids. The results showed that the maximum plasma concentration (Cmax) and the area under the plasma concentration-time curve from 0 h to infinity (AUC0→inf) of dexamethasone were increased by 2.44-fold and 2.60-fold when combined with voriconazole, respectively. For methylprednisolone, the Cmax and AUC0→inf were increased by 1.56-fold and 2.23-fold, respectively. Our results indicate that the dose of dexamethasone or methylprednisolone can be reduced to maintain approximately similar exposures when used concomitantly with voriconazole.

Granulocyte colony-stimulating factor combined with Methylprednisolone improves functional outcomes in rats with experimental acute spinal cord injury

OBJECTIVES: To evaluate the effects of combined treatment with granulocyte colony-stimulating factor (G-CSF) and methylprednisolone in rats subjected to experimental spinal cord injury. METHODS: Forty Wistar rats received a moderate spinal cord injury and were divided into four groups: control (no treatment); G-CSF (G-CSF at the time of injury and daily over the next five days); methylprednisolone (methylprednisolone for 24 h); and G-CSF/Methylprednisolone (methylprednisolone for 24 h and G-CSF at the time of injury and daily over the next five days). Functional evaluation was performed using the Basso, Beattie and Bresnahan score on days 2, 7, 14, 21, 28, 35 and 42 following injury. Motor-evoked potentials were evaluated. Histological examination of the spinal cord lesion was performed immediately after euthanasia on day 42. RESULTS: Eight animals were excluded (2 from each group) due to infection, a normal Basso, Beattie and Bresnahan score at their first evaluation, or autophagy, and 32 were evaluated. The combination of methylprednisolone and G-CSF promoted greater functional improvement than methylprednisolone or G-CSF alone (p<0.001). This combination also exhibited a synergistic effect, with improvements in hyperemia and cellular infiltration at the injury site (p<0.001). The groups displayed no neurophysiological differences (latency p=0.85; amplitude p=0.75). CONCLUSION: Methylprednisolone plus G-CSF promotes functional and histological improvements superior to those achieved by either of these drugs alone when treating spinal cord contusion injuries in rats. Combining the two drugs did have a synergistic effect.

Clinical Implication of Mycophenolic Acid Trough Concentration Monitoring in Kidney Transplant Patients on a Tacrolimus Triple Maintenance Regimen: A Single-Center Experience.

BACKGROUND This study was designed to analyze the clinical implications of mycophenolic acid trough concentration monitoring. MATERIAL AND METHODS We collected data of patients with mycophenolic acid trough concentration monitoring after their first kidney transplant between November 2006 and March 2015 who were prescribed tacrolimus, mycophenolate, and methylprednisolone. Analyses were performed on 3 periods: 1 month, 1 month to 1 year, and after 1 year post-transplantation. To analyze factors related to acute cellular rejection, logistic regression was used for 1 month, while Cox analysis was used during 1 month to 1 year and after 1 year post-transplantation. RESULTS In the 145 patients receiving mycophenolate mofetil, mean tacrolimus trough ≥7.0 ng/mL (OR=0.177, CI=0.060-0.524, p=0.002) and mean mycophenolic acid trough ≥1.7 mg/L (OR=0.190, CI=0.040-0.896, p=0.036) were protective for rejection during 1 month. Mean mycophenolic acid trough ≥1.7 mg/L (HR=0.179, CI=0.040-0.806, p=0.025) and ≥0.7 mg/L (HR=0.142, CI=0.028-0.729, p=0.019) were related to better rejection-free survival during 1 month to 1 year and after 1 year, respectively. In 399 patients receiving enteric-coated mycophenolate sodium, mean tacrolimus trough ≥7.0 ng/mL (OR=0.258, CI=0.131-0.507, p<0.001) and mean mycophenolic acid trough ≥2.1 mg/L (OR=0.507, CI=0.264-0.973, p=0.041) were protective for rejection during 1 month. Mean mycophenolic acid trough ≥1.7 mg/L (HR=0.519, CI=0.289-0.932, p=0.028) and ≥0.7 mg/L (HR=0.208, CI=0.072-0.602, p=0.004) were related to better rejection-free survival during 1 month to 1 year and after 1 year, respectively. CONCLUSIONS Mycophenolic acid trough concentration monitoring can be useful in preventing acute cellular rejection in patients receiving tacrolimus, mycophenolate, and methylprednisolone.

Pharmacokinetic drug evaluation of budesonide in the treatment of Crohn's disease.

INTRODUCTION: Crohn's disease (CD) is a chronic inflammatory disorder that commonly affects the terminal ileum and proximal colon. Although systemic corticosteroids such as prednisone and methylprednisolone are widely used for treatment of CD, these agents have a high incidence of adverse drug reactions due to off-target effects. Budesonide is a locally acting corticosteroid with enhanced formulation properties that offer a superior therapeutic index in comparison to conventional members of the class. Areas covered: This review focuses on budesonide for the treatment of CD. The pharmacological and pharmacokinetics of the drug are summarized, along with clinical efficacy and safety data. We also indicate the role of budesonide in therapeutic algorithms. Expert opinion: Budesonide has an important role as an induction therapy in patients with mild to moderately active CD of the ileum and proximal colon. The most distinctive advantage of budesonide over conventional corticosteroids is a substantially reduced risk of corticosteroid-related side effects.

Methylprednisolone aceponate for atopic dermatitis.

BACKGROUND: The 4th generation topical corticosteroids (TCS) have demonstrated a most favorablerisk-benefit ratio. Methylprednisolone aceponate (MPA) is a non-halogenated corticosteroid with a methyl group at C6, which confers higher intrinsic activity. MPA is included in the group of potent TCS (category III/IV). METHODS: A literature review is carried out of the clinical efficacy, pharmacokinetics, and adverse effects of MPA, especially for the treatment of atopic dermatitis (AD). RESULTS: Several clinical studies support the use of MPA in infants and children, with minimal local or systemic adverse effects reported. The pharmacokinetic profile and the low rate of adverse effects of MPA are most suitable for the treatment of atopic dermatitis (AD), a chronic disease with frequent flaring that can involve extensive areas of the skin. CONCLUSIONS: Most patients with AD can be easily brought into control with the use of only TCS. Achieving a complete healing of eczema is key in AD, and once the skin is clinically healthy, emollients can be used according to the physician and patient preferences. Physicians should be trained in the recognition of early or subtle manifestations of active eczema that are most suitably treated with topical TCS to achieve a most rapid and satisfactory control of the disease. If the whole area with eczema is not treated, active eczema will remain and treatment will be ineffective. Insufficient use of TCS will lead to inefficiency and frustration.