Schwann Cell-Derived Exosomes and Methylprednisolone Composite Patch for Spinal Cord Injury Repair.

Spinal cord injury (SCI) can cause permanent loss of sensory and motor function, and there is no effective clinical treatment, to date. Due to the complex pathological process involved after injury, synergistic treatments are very urgently needed in clinical practice. We designed a nanofiber scaffold hyaluronic acid hydrogel patch to release both exosomes and methylprednisolone to the injured spinal cord in a non-invasive manner. This composite patch showed good biocompatibility in the stabilization of exosome morphology and toxicity to nerve cells. Meanwhile, the composite patch increased the proportion of M2-type macrophages and reduced neuronal apoptosis in an in vitro study. In vivo, the functional and electrophysiological performance of rats with SCI was significantly improved when the composite patch covered the surface of the hematoma. The composite patch inhibited the inflammatory response through macrophage polarization from M1 type to M2 type and increased the survival of neurons by inhibition neuronal of apoptosis after SCI. The therapeutic effects of this composite patch can be attributed to TLR4/NF-κB, MAPK, and Akt/mTOR pathways. Thus, the composite patch provides a medicine-exosomes dual-release system and may provide a non-invasive method for clinical treatment for individuals with SCI.

The effects of thymoquinone on steroid-induced femoral head osteonecrosis: An experimental study in rats.

OBJECTIVES: In this study, we aimed to evaluate the antioxidant, anti-apoptotic, osteoblastic and hypolipidemic effects of thymoquinone (TQ) treatment on the steroid-induced osteonecrosis of femoral head (ONFH) model in rats. MATERIALS AND METHODS: A total of 24 rats were randomly divided into four groups: the control group administered saline; the TQ group administered 10 mg/kg/day TQ orally; lipopolysaccharide/methylprednisolone (LPS/MPS) group administered 20 µg/kg intraperitoneally LPS and 40 mg/kg intramuscularly MPS to establish ONFH model; and the LPS/ MPS+TQ group administered both LPS/MPS and, then, TQ once daily for four weeks. All rats were sacrificed after intracardiac blood collection and their right femurs were removed. RESULTS: Micro-computed tomography showed a higher bone mineral density and lower porosity, Tr. Sp and Tr. Sep data were detected in the LPS/MPS+TQ group. In histopathology, osteonecrosis increased significantly in the LPS/MPS group and osteonecrosis decreased in the LPS/MPS+TQ group compared to the LPS/MPS group (p=0.0077). Histomorphometric examination revealed that the percentage of BV/TV in the LPS/MPS group was significantly lower compared to control and other groups (p<0.01 and p<0.05, respectively), while it reached normal rates in the LPS/MPS+TQ group. Immunohistochemically, antioxidant, anti-apoptotic, and angiogenesis indicators (8-hydroxy-20- deoxyguanosine [8-OHdG], malondialdehyde [MDA], B-cell lymphoma [Bcl-2], caspase-3, vascular endothelial growth factor [VEGF]) were significantly improved in tissue and serum with TQ. Furthermore, TQ significantly reduced low- and high-density lipoprotein cholesterol ratio and carboxy-terminal type 1 collagen crosslink (CTX) in serum. CONCLUSION: Vascular and hematopoietic cell damages that occur due to steroid-induced deoxyribonucleic acid (DNA) oxidative and lipid peroxidative damages in an ONFH model can be successfully ameliorated by TQ administration. This antioxidant and anti-apoptotic effects of TQ may be a promising treatment option for early stage of osteonecrosis.

Lupus nephritis with corticosteroid responsiveness: molecular changes of CD46-mediated type 1 regulatory T cells.

BACKGROUND: The engagement of the complement regulatory proteins CD46 and CD3 in human CD4+ T cells induces the type 1 regulatory T cells (Tr1) and interleukin-10 (IL-10) secretion. This study aimed to elucidate the molecular changes of Tr1 cells through CD46 cytoplasmic Cyt1 tail in lupus nephritis (LN) respond to intravenous methylprednisolone (ivMP) therapy. METHODS: We enrolled 40 pediatric patients with LN and 30 healthy controls. Clinical characteristics and peripheral blood mononuclear cells were collected before and 3 days after the administration of ivMP. Kidney specimens were taken from five LN and five minimal-change nephrotic syndrome patients. RESULTS: We found that defective CD46-mediated T-helper type 1 contraction (IL-10 switching) is present in active LN patients. The ivMP therapy enhanced LN remission, restored the production of IL-10, increased the CD46-Cyt1/Cyt2 ratio, AKT, and cAMP-responsive element-binding protein phosphorylation, and induced migration with the expression of chemokine receptor molecules CCR4, CCR6, and CCR7 of CD3/CD46-activated Tr1 cells. CONCLUSIONS: Pharmacologic interventions that alter the patterns of CD46-Cyt1/Cyt2 expression and the secretion of IL-10 by CD3/CD46-activated Tr1 cells can be used in patients with active LN. IMPACT: In patients with LN, ivMP was associated with increased IL-10 production and increased CD46-Cyt1/Cyt2 ratio and AKT phosphorylation by Tr1 cells, with enhanced potential to migration in response to CCL17. These results suggest that expression levels of CD46 isoforms Cyt1 and Cyt2 in CD4 + CD46 + Tr1 cells differ in patients with active LN but can be corrected by corticosteroid treatment. Enhancing the expression of functional CD4 + CD46 + Tr1 cells may be a useful therapeutic approach for LN.

Methylprednisolone Attenuates Lipopolysaccharide-Induced Sepsis by Modulating the Small Nucleolar RNA Host Gene 5/Copine 1 Pathway.

Sepsis has become a major public health problem worldwide. Methylprednisolone sodium succinate (MP) is a commonly used drug to prevent inflammation. However, the role and underlying mechanism of MP in sepsis remain vague. MP inhibited the lipopolysaccharide (LPS)-induced production of tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-17 and suppressed cell growth in alveolar type II epithelial cells (ATII cells). Small nucleolar RNA host gene 5 (SNHG5) expression was inhibited by LPS and restored by MP. Upregulation of SNHG5 inhibited the cellular role of LPS in ATII cells, and further, downregulation of SNHG5 inhibited the cellular role of MP in ATII cells under LPS conditions. SNHG5 elevated the expression of Copine 1 (CPNE1) by enhancing the mRNA stability of CPNE1. Increasing CPNE1 expression restored the silenced SNHG5-induced inhibitor role of MP in ATII cells under LPS conditions. Finally, MP attenuated lung injury and TNF-α and IL-17 secretion in an LPS-induced sepsis mouse model. Overall, this study investigated the mechanism underlying the effect of MP treatment in sepsis and, for the first time, revealed the important role of the SNHG5/CPNE1 pathway in the development and treatment of sepsis and the potential to serve as a diagnostic and therapeutic target for sepsis.

Perfusate adsorption during ex vivo lung perfusion improves early post-transplant lung function.

OBJECTIVE: Improvement in ex vivo lung perfusion protocols could increase the number of donors available for transplantation and protect the lungs from primary graft dysfunction. We hypothesize that perfusate adsorption during ex vivo lung perfusion reconditions the allograft to ischemia-reperfusion injury after lung transplantation. METHODS: Donor pig lungs were preserved for 24 hours at 4°C, followed by 6 hours of ex vivo lung perfusion according to the Toronto protocol. The perfusate was additionally adsorbed through a CytoSorb adsorber (CytoSorbents, Berlin, Germany) in the treatment group, whereas control lungs were perfused according to the standard protocol (n = 5, each). Ex vivo lung perfusion physiology and biochemistry were monitored. Upon completion of ex vivo lung perfusion, a left single lung transplantation was performed. Oxygenation function and lung mechanics were assessed during a 4-hour reperfusion period. The inflammatory response was determined during ex vivo lung perfusion and reperfusion. RESULTS: The cytokine concentrations in the perfusate were markedly lower with the adsorber, resulting in improved ex vivo lung perfusion physiology and biochemistry during the 6-hour perfusion period. Post-transplant dynamic lung compliance was markedly better during the 4-hour reperfusion period in the treatment group. Isolated allograft oxygenation function and dynamic compliance continued to be superior in the adsorber group at the end of reperfusion, accompanied by a markedly decreased local inflammatory response. CONCLUSIONS: Implementation of an additional cytokine adsorber has refined the standard ex vivo lung perfusion protocol. Furthermore, cytokine removal during ex vivo lung perfusion improved immediate post-transplant graft function together with a less intense inflammatory response to reperfusion in pigs. Further studies are warranted to understand the beneficial effects of perfusate adsorption during ex vivo lung perfusion in the clinical setting.

CNS Penetration Ability: A Critical Factor for Drugs in the Treatment of SARS-CoV-2 Brain Infection.

Now, it has been evidenced that Covid19 (SARS-CoV-2) infects the brain tissues. Along with this, a challenge has been raised for research professionals to find effective drugs for its treatment since the recent spread of this virus from Wuhan, China. Targeting the treatment of brain infection, it has also been a challenge that the clinical drug should have good CNS penetration ability to cross the blood-brain barrier.

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.

α-Methyl-prednisolone normalizes the PKC mediated brain angiogenesis in dystrophic mdx mice.

A fraction of patients affected by Duchenne Muscular Dystrophy (DMD) shows mental disability as a consequence of neuronal and metabolic alteration. In this study, we evaluated the effect of α-methyl-prednisolone (PDN) on the expression of the angiogenic marker HIF1α, VEGFA and VEGFR-2 (FLK1) in correlation with PKC expression in the brain of mdx mouse, an experimental model of DMD. We demonstrated that HIF1α, VEGFA and FLK1 are overexpressed in the brain of dystrophic mdx mice in parallel with an increase of PKC expression and reduction of the tight junctions Occludin leading to altered angiogenesis. Moreover, we demonstrated that PDN treatment induces a significant reduction in the HIF1α, VEGF, FLK1, and PKC mRNA and proteins levels and restores Occludin expression reducing its phosphorylation pattern. Our results suggest a new mechanism of action of PDN that through PKC suppression normalizes the angiogenesis in dystrophic mdx brains.

Effects of branching architecture and linker on the activity of hyperbranched polymer-drug conjugates.

Drug release from hyperbranched polymer-drug conjugates and the subsequent activity are influenced by the branching architecture and the linker. To gain an understanding of these effects, we used hyperbranched polyol and G4-OH polyamidoamine (PAMAM) dendrimer with methyl prednisolone (MP) as the model drug. The drug was conjugated to dendrimer or polyol using a glutaric acid (GA) or a succinic acid (SA) spacer. Drug payload was the highest with polyol, while in the case of dendrimer, a higher payload was achieved with the GA than the SA spacer. Cell uptake of the polymer conjugates in A549 lung epithelial cells was higher than that of the free drug, and the conjugates largely localized in the cytosol. The anti-inflammatory activity of polymer conjugated MP, as measured by inhibition of prostaglandin synthesis, was the highest for MP-SA-dendrimer conjugate, followed by MP-GA-polyol conjugate, and then MP-GA-dendrimer conjugate. This study suggests that the branching architecture and spacer influence the drug payload and pharmacological activity of a drug-nanopolymer conjugate, which may significantly influence the in vivo efficacy of these nanodevices. This has key implications in the eventual in vivo efficacy of these nanodevices.

Impact of human interleukin-10 on vector-induced inflammation and early graft function in rat lung transplantation.

This study was undertaken to examine the time course of human interleukin (hIL)-10 gene expression after transtracheal administration of adenoviral (Ad)hIL-10 and its effect on the early adenoviral proinflammatory cytokine response and on post-transplant lung function. Using a rat lung transplant model, we observed that lungs retrieved 12 h after the administration of AdhIL-10 were associated with significant improvement in post-transplant lung function. Shorter periods of transfection were associated with significantly elevated levels of tumor necrosis factor-alpha and macrophage inflammatory protein-2 in lung tissue, leading to an increased degree of injury. The release of proinflammatory cytokines secondary to the adenoviral vector was reduced by high-dose methylprednisolone (30 mg/kg) administered 3 h before transfection. Reduction in the early adenoviral inflammatory response was associated with significant improvement in post-transplant lung function when lungs were retrieved 6 or 12 h after transtracheal administration of AdhIL-10. Transtracheal administration of adenoviral-mediated hIL-10 to donor lungs is associated with a significant early inflammatory response that may enhance ischemia-reperfusion injury if insufficient hIL-10 is expressed in lung tissue before retrieval. The period between delivery of AdhIL-10 and lung retrieval can be reduced if the early inflammatory response is suppressed with methylprednisolone.

Regulation of mouse mast cell surface Fc epsilon RI expression by dexamethasone.

It is now clear that the mast cell's functional response to IgE-dependent stimulation can be influenced significantly by the level of expression of the high-affinity IgE receptor (Fc epsilon RI) on the cell's surface. Thus, modulation of Fc epsilon RI surface expression represents a potentially important mechanism for regulating mast cell activity in allergic reactions. In this study, we examined whether a glucocorticoid, dexamethasone (DEX), can influence levels of mast cell Fc epsilon RI expression either in the presence or absence of IgE, an up-regulator of the mast cell surface Fc epsilon RI level. In the absence of IgE, DEX decreased the surface Fc epsilon RI levels in mouse peritoneal mast cells, mouse bone marrow-derived cultured mast cells and a mouse mast cell line, Cl.MC/C57.1. Moreover, DEX also partially suppressed the ability of IgE to enhance surface expression of Fc epsilon RI in these cells. Three different glucocorticoids, DEX, methylprednisolone and hydrocortisone, suppressed Fc epsilon RI expression in mast cells, whereas sex steroids, i.e. estradiol, progesterone and testosterone, did not, indicating that the Fc epsilon RI-suppressing effect is glucocorticoid specific. On the other hand, DEX did not affect levels of Fc epsilon RI alpha, beta or gamma mRNA, suggesting that its ability to decrease surface Fc epsilon RI reflects a post-transcriptional mechanism. Finally, DEX-treated mast cells showed a reduced degranulation response to antigenic stimulation through down-regulation of surface Fc epsilon RI expression in addition to DEX-induced changes in downstream signals. These results show that mast cell surface Fc epsilon RI expression is suppressed by glucocorticoids in both the presence and absence of IgE, and suggest that reduction of mast cell surface Fc epsilon RI levels may be one of the favorable anti-allergic actions of glucocorticoids.

Effect of intravenous corticosteroid on ex vivo leukotriene generation by blood leucocytes of normal and asthmatic patients.

BACKGROUND: The cysteinyl-leukotrienes (LTC(4), LTD(4), LTE(4)) are critical bronchoconstrictor and eosinophilotactic mediators in asthma while LTB(4) is a potent neutrophil chemoattractant. Glucocorticosteroids are front line anti-inflammatory treatment for asthma but the evidence that they reduce leukotriene (LT) synthesis in vivo is poor. METHODS: In a randomised, double blind, placebo controlled, crossover trial immunoassays were used to measure ex vivo synthesis of LTC(4) and LTB(4) by calcium ionophore stimulated blood leucocytes and bronchoalveolar lavage (BAL) cells of eight normal subjects and eight patients with mild allergic asthma 4-6 hours after intravenous administration of a single 100 mg dose of methylprednisolone. RESULTS: Ionophore stimulated synthesis of LTC(4) (but not LTB(4)) in blood granulocytes tended to be higher in asthmatic subjects (mean 9.7 ng/10(6) cells) than in normal subjects (4.2 ng/10(6) cells; p = 0.08) and intravenous methylprednisolone reduced synthesis of LTC(4) (but not LTB(4)) to normal levels (2.9 ng/10(6) cells; 95% CI for the reduction 1.0 to 12.5 ng/10(6) cells; p = 0.03). In blood mononuclear cells methylprednisolone reduced LTC(4) synthesis in asthmatic subjects from 1.26 to 0.79 ng/10(6) cells (95% CI for the reduction 0.26 to 0.79, p = 0.014) and tended to reduce LTC(4) synthesis in normal subjects from 1.51 to 0.86 ng/10(6) cells (p = 0.08). Methylprednisolone also significantly reduced synthesis of LTB(4) in mononuclear cells from both subject groups (p = 0.014). It had no effect on LT synthesis in BAL cells from either group nor on LT levels in BAL fluid. CONCLUSIONS: Intravenous methylprednisolone can reduce synthesis of leukotrienes in blood granulocytes and mononuclear cells within six hours of a single intravenous dose.

High-performance liquid chromatography analysis, preliminary pharmacokinetics, metabolism and renal excretion of methylprednisolone with its C6 and C20 hydroxy metabolites in multiple sclerosis patients receiving high-dose pulse therapy.

A gradient eluent HPLC analysis in human plasma and urine was developed and validated for methylprednisolone (MP), its prodrug methylprednisolone-21-hemisuccinate (MPS) with the metabolites 6beta-hydroxy-6alpha-methylprednisolone (MPA), 20-hydroxymethylprednisolone (MPC), 6beta-hydroxy-20alpha-hydroxymethylprednisolone (MPB), 6beta-hydroxy-20beta-hydroxymethylprednisolone (MPE), 20-carboxymethylprednisolone (MPD), methylprednisolone-glucuronide (MPF) and 21-carboxymethylprednisolone (MPX). The column was Cp Spherisorb C8 5 microm, 250 mm x 4.6 mm I.D. (Chrompack, Bergen op Zoom, The Netherlands) with a guard column 75 mm x 2.1 mm, packed with pellicular reversed-phase. The eluent was a mixture of acetonitrile and 0.067 M KH2PO4 buffer, pH 4.5. At t=O, the eluent consisted of 2% acetonitrile and 98% buffer (v/v). Over the following 35 min the eluent changed linearly until it attained a composition of 50% acetonitrile and 50% buffer (v/v). At 37 min (t=37) the eluent was changed over 5 min to the initial composition, followed by equilibration over 3 min. The flow-rate was 1.5 ml/min and UV detection was achieved at 248 nm. Preliminary pharmacokinetic data were obtained from one patient who showed illustrative plasma concentration-time curves and renal excretion-time profiles after a short-lasting infusion (0.5 h) of 1 g of methylprednisolone hemisuccinate. The half-life of prodrug methylprednisolone-21-hemisuccinate (MPS) was 0.3 h, that of metabolite MPX (21-carboxy MP) was 0.4 h and that of the parent drug methylprednisolone (MP) was 1.4 h. The half-lives of the metabolites are almost similar (4 h). The main compounds in the urine are methylprednisolone hemisuccinate (prodrug, 15.0%), methylprednisolone (parent drug, 14.6%), metabolite MPD (20-carboxy, 11.7%), and metabolite MPB (13.2%). The renal clearance values of metabolites MPB, MPC and MPD are approximately 500 ml/min, that of MP is 100 ml/min.

Respuesta insulínica a una carga aguda de glucosa en pacientes con anemia aplástica / Insulin response to glucose tolerance test in children with aplastic anemia

Introducción. Para investigar la existencia de resistencia periférica a la insulina y de hiperinsulinemia en pacientes con anemia aplástica (AA) previas al inicio de la terapia esteroidea y con el objeto de evaluar el riesgo de desarrollar diabetes mellitus no dependiente de insulina se diseñó el presente estudio. Material y métodos. Se estudiaron once pacientes con diagnóstico de AA adquirida de idiopático y se compararon con diez niños sanos como grupo control; todos los pacientes con AA tenían pruebas de función hepática y renal normales, antecedentes negativos de transfusión durante las cuatro semanas previas al estudio. A todos se les realizó curva de tolerancia oral a la glucosa (CTOG) de dos horas con previa dieta de 150 g de carbohidratos al día por tres días; se determinó glucosa e insulina sérica a los 0, 5, 10, 15, 30, 60, 90, y 120 minutos, analizadas por métodos de glucosa oxidasa y radioinmunoanálisis respectivamente. Se determinó la presencia de resistencia periférica a la insulina (RPT) e hiperinsulinemia a través de calcular actividad periférica de insulina (API), secreción integrada de insulina (SII) y relación glucosa-insulina (G/I). Resultados. Todos nuestros pacientes con AA presentaron hiperinsulinemia y RPI, evidenciado la primera por hiperrespuesta a una CTOG, relación G/I disminuida, niveles mayores de SII versus controles (217.6 ñ 180 vs 112.3 ñ 68),P < 0.02 y la segunda por la API menor que en los controles (0.55 ñ 0.13 vs 1.19 ñ 0.5),P < 0.01; no se encontró correlación con cifras de hemoglobina (hipoxia) y los niveles de insulina. Posterior al estudio y durante su evolución tres pacientes con AA desarrollaron diabetes mellitus. Conclusiones. La existencia de una SII elevada en los pacientes con AA más una API menor que los controles, hacen evidente una RPI, previo al inicio del tratamiento esteroideo, por lo cual es conveniente realizar CTOG a los pacientes con AA al momento del diagnóstico para detectar en forma temprana a aquellos pacientes con alteración en la secreción de insulina

Binding of the anti-inflammatory steroid deflazacort to glucocorticoid receptors in brain and peripheral tissues. In vivo and in vitro studies.

Deflazacort (DFC) is a heterocyclic glucocorticoid with anti-inflammatory activity but with decreased side effects. In this study, we have evaluated the capacity of DFC and other glucocorticoids to reach the central nervous system (CNS) in vivo by measuring changes of [3H]dexamethasone (DEX) binding to glucocorticoid receptors (GR) in vitro. GR occupation was effected by DEX in the cerebral cortex, hippocampus, pituitary, liver and thymus, with DFC showing a similar profile except for the cerebral cortex. In contrast, corticosterone weakly occupied GR in the thymus, pituitary and hippocampus and methyl-prednisolone was active only in peripheral tissues. Furthermore, IC50 for DEX in vitro amounted to 15-17 nM in the hippocampus and liver, whereas IC50 for the active metabolite 21-deacetyl-DFC (21-OH-DFC) was 4 times higher. 21-OH-DFC bound to type II and was absent from type I GR. When tested in equipotent doses based on IC50 analysis, DFC and DEX similarly induced in vivo ornithine decarboxylase activity in hippocampus and liver, although body weight loss after chronic treatment was significantly less for DFC. The results show that DFC distributes on the CNS similarly to DEX, induces ornithine decarboxylase activity but presents less intensive catabolic effects, making it suitable for use as an anti-inflammatory steroid during chronic therapeutic regimes.

Enhancement of tissue delivery and receptor occupancy of methylprednisolone in rats by a liposomal formulation.

A liposomal formulation of methylprednisolone (L-MPL) was developed to improve localization of this immunosuppressant in lymphatic tissues. Liposomes containing MPL were formulated from a mixture of phosphatydylcholine and phosphatydylglycerol (molar ratio, 9:1) and sized by extrusion through a 0.1-micron membrane. Male Sprague-Dawley rats received a bolus dose of 2 mg/kg of L-MPL or free MPL in solution (control). Samples of blood, spleen, liver, thymus, and bone marrow were collected at intervals over a 66-hr period. Concentrations of MPL in plasma and organs and free cytosolic glucocorticoid receptors (GCR) in spleen and liver were determined. The plasma MPL profiles for free and L-MPL were bi- and triexponential. Although the alpha phase kinetics of both dosage forms were similar, L-MPL showed a substantially slower elimination phase than did free drug. Incorporation of MPL into liposomes caused the following increases: terminal half-life, from 0.48 (MPL) to 30.13 hr (L-MPL); MRT, from 0.42 to 11.95 hr, Vss, from 2.10 to 21.87 L/kg; and AUC, from 339 to 1093 ng x hr/mL. Uptake of liposomes enhanced significantly the delivery of drug to lymphatic tissues and liver; AUC tissue:plasma ratios for spleen increased 77-fold; for liver, 9-fold; and for thymus, 27-fold. The duration of GCR occupancy was extended 10-fold in spleen and 13-fold in liver by the liposomal formulation. Lymphatic tissue selectivity and extended receptor binding of liposome-delivered MPL offer promise for enhanced immunosuppression.

Metabolic fate of alclometasone dipropionate in rats, rabbits, and mice. Metabolic products and pathway following subcutaneous administration.

The metabolic fate of alclometasone dipropionate (ADP or S-3460) has been studied in rats, rabbits, and mice, with consideration of their interspecies differences. Several reference compounds related to ADP were synthesized for the determination and identification of the metabolites. After sc administration of 14C-labeled ADP, the metabolites in plasma, bile, and urine were separated and analyzed using TLC-ARG (autoradiography) and HPLC in comparison with the reference compounds. The metabolites identified, fully or tentatively, by MS and 1H-NMR totaled 11. The metabolic transformations were: hydrolysis of the side chain esters, dehydrochlorination leading to the formation of delta 6-double bond, 6 beta-hydroxylation, 6 beta, 7 beta-epoxides from 6 beta-hydroxylated metabolites, side chain oxidation to 21-oic and 20-oic acids in the 6 beta-hydroxylated metabolites, and conjugation to glucuronides and sulfates. The metabolic pathway, postulated on the basis of the identified and quantitated metabolites, was a rapid hydrolysis of 21-ester of ADP to the corresponding alcohol, M-1, after systemic uptake. This M-1 was a main metabolite in plasma of animals studied, and due to its relatively longer life time in the media, it seemed to allow a variety of metabolism to occur, giving the oxidative and conjugative metabolites mentioned above.

Echographic localization of corticosteroids after periocular injection.

The location of repository corticosteroid after subtenon injection was determined in 24 patients with macular edema associated with uveitis or anterior segment surgery. Standardized A-scan and B-scan echography were performed immediately before and after each injection. Localization was compared after subtenon injection in either the superior or inferior temporal quadrants. Echography showed that corticosteroid was deposited within the subtenon space over the macula in 11 of 24 cases. The therapeutic response manifested by improvement in macular function may be related to the proximity of the corticosteroid to the macular area. Lack of therapeutic response to repository corticosteroids may be because of placement at a site relatively far from the target zone.

Chronopharmacology.

The time of day that drugs are given can have a profound effect upon both their pharmacodynamics, i.e. their effectiveness and toxicity, and their pharmacokinetics, i.e. the way they themselves behave in the body. The chronopharmacokinetics of relatively few drugs have been investigated and are mostly those used for the treatment of cancer. We have shown that the toxicity and chronopharmacokinetics of drugs can be altered by pretreatment with steroids or melatonin.