Methylprednisolone Concentrations in Breast Milk and Serum of Patients with Multiple Sclerosis Treated with IV Pulse Methylprednisolone.

BACKGROUND: It is commonly known that women with multiple sclerosis (MS) have an increased risk for relapses during the post-partum period. High-dose IV methylprednisolone is the first-line treatment for acute relapses. Methylprednisolone is administered to lactating women although there is insufficient data as to the levels of concentration in breast milk and serum, and the calculated steroid exposure to infants. OBJECTIVES: The study aimed to measure the transfer of methylprednisolone into breast milk and the correlation of milk and serum methylprednisolone concentrations in breastfeeding MS patients during and after infusion therapy. METHODS: IV methylprednisolone pulse therapy was given to 12 lactating MS patients. Breast milk and maternal serum samples were obtained; before infusion, 30 minutes into the infusion, at the end of infusion and at the 1st, 2nd, 4th, 8th, 12th and 24th hours subsequently. RESULTS: The highest level of methylprednisolone concentration in breast milk (2.09 µg/ml) and serum (6.09 µg/ml) was detected at the end of the infusion. According to the measurements recorded at the 1st, 2nd, 4th, 8th, 12th, and 24th hours after infusion, the concentrations showed a gradual decrease both breast milk and serum. The milk and serum methylprednisolone concentrations were below detection limits just before infusion and at the 24th hour after infusion. A highly significant correlation was found between breast milk and maternal serum levels. The absolute infant dose was calculated to be 69.50 µg/kg/day and the relative infant dose (RID) was 0.50%. CONCLUSION: Results have shown that the transfer of methylprednisolone into breast milk seems to be low. Although, concentration levels may not seem to pose a threat to the infant, mothers can choose to wait 2 to 4 hours to further limit the level of exposure.

The Impact of Immunomodulatory Treatment on Kappa Free Light Chains as Biomarker in Neuroinflammation.

BACKGROUND: Kappa free light chains (KFLC) are a promising new biomarker to detect neuroinflammation. Still, the impact of pre-analytical effects on KFLC concentrations was not investigated. METHODS: KFLC concentrations were measured in serum and cerebrospinal fluid (CSF) of patients with a newly diagnosed multiple sclerosis (MS) or clinically isolated syndrome (CIS) before (n = 42) or after therapy with high-dose methylprednisolone (n = 65). In prospective experiments, KFLC concentrations were analyzed in the same patients in serum before and after treatment with high-dose methylprednisolone (n = 16), plasma exchange (n = 12), immunoadsorption (n = 10), or intravenous immunoglobulins (n = 10). In addition, the influence of storage time, sample method, and contamination of CSF with blood were investigated. RESULTS: Patients diagnosed with MS/CIS and treated with methylprednisolone showed significantly lower KFLC concentrations in serum as untreated patients. Repeated longitudinal investigations revealed that serum KFLC concentrations continuously decreased after each application of methylprednisolone. In contrast, other immune therapies and further pre-analytical conditions did not influence KFLC concentrations. CONCLUSION: Our results show prominent effects of steroids on KFLC concentrations. In contrast, various other pre-analytical conditions did not influence KFLC concentrations, indicating the stability of this biomarker.

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.

High-Dose Methylprednisolone Has No Benefit Over Moderate Dose for the Correction of Tetralogy of Fallot.

BACKGROUND: The optimal dose of methylprednisolone during pediatric open heart surgical procedures is unknown. This study compared the antiinflammatory and cardioprotective effects of high and lower doses of methylprednisolone in children undergoing cardiac operations. METHODS: Thirty children, between 1 and 18 months old and undergoing total correction of tetralogy of Fallot, were randomized in double-blind fashion to receive either 5 or 30 mg/kg of intravenous methylprednisolone after anesthesia induction. Plasma concentrations of methylprednisolone, interleukin-6 (IL-6), IL-8, and IL-10, troponin T, and glucose were measured at anesthesia induction before administration of the study drug, at 30 minutes on cardiopulmonary bypass (CPB), just after weaning from CPB, and at 6 hours after CPB. Troponin T and blood glucose were also measured on the first postoperative morning. RESULTS: Significantly higher methylprednisolone concentrations were measured in patients receiving 30 mg/kg of methylprednisolone at 30 minutes on CBP, after weaning from CPB and at 6 hours after CPB (p < 0.001). No differences were detected in IL-6, IL-8, IL-10, or troponin concentrations at any time point. Blood glucose levels were significantly higher in patients receiving 30 mg/kg of methylprednisolone at 6 hours after CPB (p = 0.04) and on the first postoperative morning (p = 0.02). CONCLUSIONS: Based on the measured concentrations of interleukins or troponin T, a 30 mg/kg dose of methylprednisolone during pediatric open heart operations does not offer any additional antiinflammatory or cardioprotective benefit over a 5 mg/kg dose. Higher dose of methylprednisolone exposes patients more frequently to hyperglycemia.

Prophylactic methylprednisolone to reduce inflammation and improve outcomes from one lung ventilation in children: a randomized clinical trial.

BACKGROUND: One lung ventilation (OLV) results in inflammatory and mechanical injury, leading to intraoperative and postoperative complications in children. No interventions have been studied in children to minimize such injury. OBJECTIVE: We hypothesized that a single 2-mg·kg(-1) dose of methylprednisolone given 45-60 min prior to lung collapse would minimize injury from OLV and improve physiological stability. METHODS: Twenty-eight children scheduled to undergo OLV were randomly assigned to receive 2 mg·kg(-1) methylprednisolone (MP) or normal saline (placebo group) prior to OLV. Anesthetic management was standardized, and data were collected for physiological stability (bronchospasm, respiratory resistance, and compliance). Plasma was assayed for inflammatory markers related to lung injury at timed intervals related to administration of methylprednisolone. RESULTS: Three children in the placebo group experienced clinically significant intraoperative and postoperative respiratory complications. Respiratory resistance was lower (P = 0.04) in the methylprednisolone group. Pro-inflammatory cytokine IL-6 was lower (P = 0.01), and anti-inflammatory cytokine IL-10 was higher (P = 0.001) in the methylprednisolone group. Tryptase, measured before and after OLV, was lower (P = 0.03) in the methylprednisolone group while increased levels of tryptase were seen in placebo group after OLV (did not achieve significance). There were no side effects observed that could be attributed to methylprednisolone in this study. CONCLUSIONS: Methylprednisolone at 2 mg·kg(-1) given as a single dose prior to OLV provides physiological stability to children undergoing OLV. In addition, methylprednisolone results in lower pro-inflammatory markers and higher anti-inflammatory markers in the children's plasma.

An Economical Online Solid-Phase Extraction LC-MS/MS Method for Quantifying Methylprednisolone.

An economical, reproducible and automated online solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry method was developed to quantify methylprednisolone in human plasma. The method was validated in terms of selectivity, precision/accuracy, process efficiency, stability, cartridge reproducibility and carryover studies. Sample pretreatment was performed by protein precipitation and elimination using methanol followed by water dilution. Then, the mixture was passed onto the HySphere C8 EC-SE online solid-phase extraction cartridge followed by the separation of the analytes on an Agilent Eclipse XDB column. Electrospray ionization in positive ion mode and multiple reaction monitoring were used to monitor the ion transitions at m/z 375.4/160.8 for methylprednisolone, and m/z 361.2/147.0 for prednisolone. The calibration curve ranged from 5.25 to 525 ng/mL. Meanwhile both the intra-day and inter-day precision values (relative standard deviation) were within 4.45%. The method which turns out to be less laborious, faster and lower consumable cost per sample has already been successfully applied to a pharmacokinetic study in which the oral administration of 16 mg methylprednisolone was conducted in Chinese volunteers.

What do we know about steroids metabolism and 'PK/PD approach' in AKI and CKD especially while on RRT--current status in 2014.

The knowledge on PK behavior of steroid drugs such as prednisolone or prednisone has indeed been expanding but at a rather slow pace. First, convenient, rapid, and specific determination of plasma levels of these steroids was largely indebted to the breakthrough of high performance liquid chromatography (HPLC). Second, prednisolone is non-linearly protein-bound. Since unbound prednisolone is the biologically active compound, only the measurement of this free fraction in plasma is relevant. Third, the short half-life of prednisolone precludes to reach steady-state levels and requires determination of the area under the concentration-time curve. Fourth, prednisolone and prednisone are mutually convertible. Intravenous prednisolone, however, is administered as a pro-drug ester, which renders comparison and interpretation of reported PK data of both agents unreliable. A poignant lack of awareness and knowledge regarding catabolism, clearance mechanisms, and elimination route of steroids fuels the ongoing controversy that surrounds adjunctive corticosteroid therapy in patients with chronic or acute inflammatory disease. This particular patient population is also more prone to develop early and significant kidney dysfunction, necessitating extra-renal support. A better understanding of steroid PK/PD, preferentially guided by HPLC measurement of plasma steroid concentrations, likely will have direct clinical implications, for instance by adapting steroid doses in IHD or implementing higher dose regimens during CRRT.

Polyethylene glycol modified magnetic carbon nanotubes as nanosorbents for the determination of methylprednisolone in rat plasma by high performance liquid chromatography.

In this paper, polyethylene glycol modified (PEGylated) magnetic carbon nanotubes were developed as solid-phase extraction nanosorbents for the determination of methylprednisolone in rat plasma. The procedure mainly involved two steps including preparation of PEGylated magnetic nanosorbents and bioanalysis. Monodisperse magnetites (Fe3O4) anchored onto multi-walled carbon nanotubes (MWCNTs) were synthesized by a facile solvothermal synthesis method. The obtained MWCNTs-Fe3O4 nanomaterials were further non-covalently functionalized by a surfactant phospholipids-polyethylene glycol (DSPE-PEG). Owing to dispersibility and high enrichment ability, water-soluble PEGylated MWCNTs-Fe3O4 nanomaterials can provide more efficient way for the extraction of methylprednisolone than only MWCNTs-Fe3O4 used. The methylprednisolone could be easily extracted via π-π stacking interactions with PEGylated MWCNTs-Fe3O4. The captured methylprednisolone/nanosorbents were isolated from the matrix by placing a magnet, and desorbed by the elution solvent composed of acetonitrile. Extraction conditions such as amount of nanosorbents added, adsorption time, desorption solvent, and desorption time were investigated and optimized. The method recoveries were obtained from 88.2% to 92.9%. Limits of quantification and limits of detection of 0.01 and 0.005µg/mL were acquired, respectively. The precision ranged from 4.2% to 7.8% for within-day measurement, and for between-day variation was in the range of 5.5-9.0%. Moreover, the analytical performance obtained by PEGylated magnetic MWCNTs was compared with that of magnetic MWCNTs. The results indicated that the approach based on PEGylated magnetic MWCNTs was useful for the analysis of methylprednisolone in the complex plasma.

Glutathione pegylated liposomal methylprednisolone administration after the early phase of status epilepticus did not modify epileptogenesis in the rat.

It has been reported that glucocorticoids (GCs) can effectively control seizures in pediatric epilepsy syndromes, possibly by inhibition of inflammation. Since inflammation is supposed to be involved in epileptogenesis, we hypothesized that treatment with GCs would reduce brain inflammation and thereby modify epileptogenesis in a rat model for temporal lobe epilepsy, in which epilepsy gradually develops after electrically induced status epilepticus (SE). To prevent the severe adverse effects that are inevitable with long-term GC treatment, we used liposome nanotechnology (G-Technology(®)) to enhance the sustained delivery to the brain. Starting 4h after onset of SE, rats were treated with glutathione pegylated liposomal methylprednisolone (GSH-PEG liposomal MP) according to a treatment protocol (1× per week; 10mg/kg) that is effective in other models of neuroinflammation. Continuous electro-encephalogram (EEG) recordings revealed that SE duration and onset of spontaneous seizures were not affected by GSH-PEG liposomal MP treatment. The number and duration of spontaneous seizures were also not different between vehicle and GSH-PEG liposomal MP-treated animals. Six weeks after SE, brain inflammation, as assessed by quantification of microglia activation, was not reduced by GSH-PEG liposomal MP-treatment. Also, neuronal cell loss and mossy fiber sprouting were not affected. Our study shows that the selected GSH-PEG liposomal MP treatment regimen that was administered beyond the acute SE phase does not reduce brain inflammation and development of temporal lobe epilepsy.

Simultaneous bilateral knee injection of methylprednisolone acetate and the hypothalamic-pituitary adrenal axis: a single-blind case-control study.

OBJECTIVE: The objective of this study was to evaluate the effect of simultaneous bilateral intra-articular injection (IAI) of methylprednisolone acetate (MPA) on the hypothalamic-pituitary-adrenal axis in patients with knee osteoarthritis. METHODS: Nonselected patients with symptomatic bilateral knee osteoarthritis had simultaneous IAI of 80 mg MPA at each knee (group 1). Just before the injection and on weeks 1, 2, 4, 6, and 8 after it, patients had 1 µg adrenocorticotropin hormone stimulation test. Age- and sex-matched patients had simultaneous IAI of 60 mg of hyaluronic acid in each knee (group 2) and the same protocol of adrenocorticotropin hormone stimulation tests. Demographic, clinical, and laboratory parameters were documented in all the patients. Secondary adrenal insufficiency (SAI) was defined as poststimulation serum cortisol levels of less than 18 µg/dL. RESULTS: Twenty patients were enrolled in each group. There were 15 women and 5 men in each group. Mean age of the patients in group 1 was 60.3 (SD, 7.6) years. Twelve patients (60%) from group 1 had evidence of SAI versus 3 patients in group 2 (P = 0.003). In all the patients who had SAI in group 1, it was observed in week 1 with decreasing frequency of SAI at the subsequent time points. Yet, 2 patients (10%) from group 1 had evidence of SAI 8 weeks after the IAI. Secondary adrenal insufficiency did not significantly correlate with any demographic, clinical, or laboratory parameter. CONCLUSIONS: Secondary adrenal insufficiency was very common following simultaneous bilateral IAI of 80 mg of MPA. Although it was transient, SAI could still be observed nearly 2 months after the IAI, in 10% of the patients.

Disposition of methylprednisolone acetate in plasma, urine, and synovial fluid following intra-articular administration to exercised thoroughbred horses.

Methylprednisolone acetate (MPA) is commonly administered to performance horses, and therefore, establishing appropriate withdrawal times prior to performance is critical. The objectives of this study were to describe the plasma pharmacokinetics of MPA and time-related urine and synovial fluid concentrations following intra-articular administration to sixteen racing fit adult Thoroughbred horses. Horses received a single intra-articular administration of MPA (100 mg). Blood, urine, and synovial fluid samples were collected prior to and at various times up to 77 days postdrug administration and analyzed using tandem liquid chromatography-mass spectrometry (LC-MS/MS). Maximum measured plasma MPA concentrations were 6.06 ± 1.57 at 0.271 days (6.5 h; range: 5.0-7.92 h) and 6.27 ± 1.29 ng/mL at 0.276 days (6.6 h; range: 4.03-12.0 h) for horses that had synovial fluid collected (group 1) and those that did not (group 2), respectively. The plasma terminal half-life was 1.33 ± 0.80 and 0.843 ± 0.414 days for groups 1 and 2, respectively. MPA was undetectable by day 6.25 ± 2.12 (group 1) and 4.81 ± 2.56 (group 2) in plasma and day 17 (group 1) and 14 (group 2) in urine. MPA concentrations in synovial fluid remained above the limit of detection (LOD) for up to 77 days following intra-articular administration, suggesting that plasma and urine concentrations are not a good indicator of synovial fluid concentrations.

Pharmacokinetics of methylprednisolone acetate after intra-articular administration and subsequent suppression of endogenous hydrocortisone secretion in exercising horses.

OBJECTIVE: To determine the pharmacokinetics of methylprednisolone (MP) and the relationship between MP and hydrocortisone (HYD) concentrations in plasma and urine after intra-articular (IA) administration of 100 or 200 mg of MP acetate (MPA) to horses. ANIMALS: Five 3-year-old Thoroughbred mares. PROCEDURES: Horses exercised on a treadmill 3 times/wk during the study. Horses received 100 mg of MPA IA, then 8 weeks later received 200 mg of MPA IA. Plasma and urine samples were obtained at various times for 8 weeks after horses received each dose of MPA; concentrations of MP and HYD were determined. Pharmacokinetic-pharmacodynamic estimates for noncompartmental and compartmental parameters were determined. RESULTS: Maximum concentration of MP in plasma was similar for each MPA dose; concentrations remained greater than the lower limit of quantitation for 18 and 7 days after IA administration of 200 and 100 mg of MPA, respectively. Maximum concentration and area under the observed concentration-time curve for MP in urine were significantly higher (approximately 10-and 17-fold, respectively) after administration of 200 versus 100 mg of MPA. Hydrocortisone concentration was below quantifiable limits for ≥ 48 hours in plasma and urine of all horses after administration of each MPA dose. CONCLUSIONS AND CLINICAL RELEVANCE: Pharmacokinetics of MP may differ among IA MPA dosing protocols, and MP may be detected in plasma and urine for a longer time than previously reported. This information may aid veterinarians treating sport horses. Further research is warranted to determine whether plasma HYD concentration can aid identification of horses that received exogenous glucocorticoids.

Mechanistic modeling of the effects of glucocorticoids and circadian rhythms on adipokine expression.

A mechanism-based model was developed to describe the effects of methylprednisolone (MPL), circadian rhythms, and the glucose/free fatty acid (FFA)/insulin system on leptin and adiponectin expression in white adipose tissue in rats. Fifty-four normal Wistar rats received 50 mg/kg MPL intramuscularly and were sacrificed at various times. An additional set of 54 normal Wistar rats were sacrificed at 18 time points across the 24-h light/dark cycle and served as controls. Measurements included plasma MPL, glucocorticoid receptor (GR) mRNA, leptin mRNA, adiponectin mRNA, plasma leptin, adiponectin, glucose, FFA, and insulin. MPL pharmacokinetics was described by a two-compartment model with two absorption components. All measured plasma markers and mRNA expression exhibited circadian patterns except for adiponectin and were described by Fourier harmonic functions. MPL caused significant down-regulation in GR mRNA with the nadir occurring at 5 h. MPL disrupted the circadian patterns in plasma glucose and FFA by stimulating their production. Plasma glucose and FFA subsequently caused an increase in plasma insulin. Furthermore, MPL disrupted the circadian patterns in leptin mRNA expression by stimulating its production. This rise was closely followed by an increase in plasma leptin. Both leptin mRNA and plasma leptin peaked at 12 h after MPL and eventually returned back to their circadian baselines. MPL and insulin had opposing effects on adiponectin mRNA expression and plasma adiponectin, which resulted in biphasic pharmacodynamic profiles. This small systems model quantitatively describes, integrates, and provides additional insights into various factors controlling adipokine gene expression.

Dynamic modeling of methylprednisolone effects on body weight and glucose regulation in rats.

Influences of methylprednisolone (MPL) and food consumption on body weight (BW), and the effects of MPL on glycemic control including food consumption and the dynamic interactions among glucose, insulin, and free fatty acids (FFA) were evaluated in normal male Wistar rats. Six groups of animals received either saline or MPL via subcutaneous infusions at the rate of 0.03, 0.1, 0.2, 0.3 and 0.4 mg/kg/h for different treatment periods. BW and food consumption were measured twice a week. Plasma concentrations of MPL and corticosterone (CST) were determined at animal sacrifice. Plasma glucose, insulin, and FFA were measured at various times after infusion. Plasma MPL concentrations were simulated by a two-compartment model and used as the driving force in the pharmacodynamic (PD) analysis. All data were modeled using ADAPT 5. The MPL treatments caused reduction of food consumption and body weights in all dosing groups. The steroid also caused changes in plasma glucose, insulin, and FFA concentrations. Hyperinsulinemia was achieved rapidly at the first sampling time of 6 h; significant elevations of FFA were observed in all drug treatment groups; whereas only modest increases in plasma glucose were observed in the low dosing groups (0.03 and 0.1 mg/kg/h). Body weight changes were modeled by dual actions of MPL: inhibition of food consumption and stimulation of weight loss, with food consumption accounting for the input of energy for body weight. Dynamic models of glucose and insulin feedback interactions were extended to capture the major metabolic effects of FFA: stimulation of insulin secretion and inhibition of insulin-stimulated glucose utilization. These models of body weight and glucose regulation adequately captured the experimental data and reflect significant physiological interactions among glucose, insulin, and FFA. These mechanism-based PD models provide further insights into the multi-factor control of this essential metabolic system.

Development of superparamagnetic high-magnetization C18-functionalized magnetic silica nanoparticles as sorbents for enrichment and determination of methylprednisolone in rat plasma by high performance liquid chromatography.

In this study, a novel extraction and enrichment technique based on superparamagnetic high-magnetization C(18)-functionalized magnetic silica nanoparticles (C(18)-MNPs) as sorbents was successfully developed for the determination of methylprednisolone (MP) in rat plasma by high performance liquid chromatography (HPLC). The synthesized silica-coated magnetite modified with chlorodimethyl-n-octadecylsilane was about 320 nm in diameter with strong magnetism and high surface area. It provided an efficient way for extraction and concentration of MP in the samples through hydrophobic interaction by the interior C(18) groups. Moreover, MP adsorbed with C(18)-MNPs could be simply and rapidly isolated through placing a strong magnet on the bottom of container, and then easily eluted from C(18)-MNPs by n-hexane solution. Extraction conditions such as amounts of C(18)-MNPs added, adsorption time and desorption solvent, were investigated. Method validations including linear range, detection limit, precision, and recovery were also studied. The results showed that the proposed method based on C(18)-MNPs was a simple, accurate and high efficient approach for the analysis of MP in the complex plasma samples.

Pharmacokinetics of mycophenolic acid in living donor liver transplantation.

PURPOSE: This study sought to define the pharmacokinetics of mycophenolic acid (MPA) in Korean living donor liver transplant recipients. METHODS: Thirty-two liver transplant recipients (29 males, 3 females) were administered 750 mg mycophenolate mofetil (MMF) twice daily with concomitant tacrolimus. Plasma MPA concentrations were measured by liquid chromatography with tandem mass spectrometry detection assay from samples drawn before dosing (C0) and after dosing at 0.5 hours (C1/2) and 2 hours (C2), providing a total of 114 pharmacokinetic profiles at various periods from 3 days to 6 months posttransplantation (D3, D7, D14, M1, M3, and M6). RESULTS: The mean area-under-the-curve from 0 to 2 hours (AUC0-2) was 30.0+/-11.6 microg.h/mL (range, 7.8-60.7). Of 114 pharmacokinetic profiles, 40 (35%) AUC and 7 (6.1%) trough values were within the target value (30-60 microg.h/mL and 1.7-4.0 microg/mL, respectively). The C0, C1/2, and C2 concentrations showed large interindividual variability: C0 (0.01-4.46 microg/mL), C1/2 (0.14-36.86 microg/mL), and C2 (0.79-18.19 microg/mL). A positive correlation was observed between AUC and C0 (r=.6374; P<.0001), and C2 (r=.7460; P<.0001). When analyzed according to the date posttransplant, a positive correlation between AUC and C0 was shown on day 7, day 14, and at month 1. There was no difference in any pharmacokinetic parameter relative to age, weight, or albumin level. CONCLUSION: This study demonstrated that C0 values on day 7, day 14, and at month 1 provided valuable information for MPA monitoring. C0 was shown to be the most reliable monitoring time in relation to AUC. However, results from a larger randomized trial with more time intervals are eagerly awaited.

Plasma pharmacokinetics and tissue disposition of novel dextran-methylprednisolone conjugates with peptide linkers in rats.

The plasma and tissue disposition of two novel dextran prodrugs of methylprednisolone (MP) containing one (DMP-1) or five (DMP-5) amino acids as linkers were studied in rats. Single 5-mg/kg doses (MP equivalent) of each prodrug or MP were administered intravenously, and blood and tissue samples were collected. Prodrug and drug concentrations were quantitated using HPLC, and noncompartmental pharmacokinetic parameters were estimated. Whereas conjugation of MP with dextran in both prodrugs substantially decreased the clearance of the drug by approximately 200-fold, the accumulations of the drug in the liver, spleen, and kidneys were significantly increased by conjugation. However, the extent of accumulation of DMP-1 in these tissues was substantially greater than that for DMP-5. Substantial amounts of MP were regenerated from both prodrugs in the liver and spleen, with the rate of release from DMP-5 being twice as fast as that from DMP-1. However, the AUCs of MP regenerated from DMP-1 in the liver and spleen were substantially higher than those after DMP-5. In contrast, in the kidneys, the AUC of MP regenerated from DMP-5 was higher than that after DMP-1 administration. These data suggest that DMP-1 may be more suitable than DMP-5 for targeting immunosuppression to the liver and spleen.

A rapid and sensitive LC-ESI-MS/MS method for detection and quantitation of methylprednisolone and methylprednisolone acetate in rat plasma after intra-articular administration.

A rapid, sensitive and specific liquid chromatography-electrospray-tandem mass spectrometric (LC-ESI-MS/MS) method for the simultaneous detection and quantitation of methylprednisolone acetate (MPA) and methylprednisolone (MP) in rat plasma, using a triple-stage quadrupole, has been developed and validated. MP-D(2) was used as internal standard (IS) and acetonitrile was added to plasma samples for protein precipitation. After extraction with dichloromethane, the analytes were separated on a C-12 reversed-phase column by isocratic elution (6min at a flow rate 0.2mLmin(-1)) with water containing 0.01% formic acid (A) and acetonitrile (B) (50:50, v/v). Quantitation was performed in positive ion multiple reaction monitoring (MRM) mode by applying the following precursor-to-product ion transitions: MPA m/z 417-->135+161+253; MP m/z 375-->135+161+253; IS m/z 377-->135+161+253. The method, validated over the concentration range 6-600ngmL(-1), has been shown to meet the current requirements of bioananalytical validation, providing satisfactory results in terms of linearity, recovery, intra-day and inter-day precision and accuracy. The lower limit of quantitation (LLOQ) was 6ngmL(-1) for both the analytes (0.080 and 0.072pmol injected for MP and MPA, respectively). The method was successfully applied to monitor the plasma levels of MPA and MP following intra-articular (IA) injections of a low MPA (Depo-Medrol((R))) dose in rats.

A single-wall carbon nanotubes modified edge plane pyrolytic graphite sensor for determination of methylprednisolone in biological fluids.

An electrochemical protocol based on reduction is developed to determine methylprednisolone using single-wall carbon nanotubes (SWNTs) modified edge plane pyrolytic graphite electrode (EPPGE). To obtain a good sensitivity, instrumental variables were studied using Square Wave Voltammetry (SWV). The voltammetric results indicate that SWNTs modified EPPGE remarkably enhances the reduction of methylprednisolone which leads to considerable improvement of peak current with shift of peak potential to less negative values. The voltammetric current showed a linear response for methylprednisolone concentration in the range 5-500 nM with a sensitivity of 98 nA nM(-1). The limit of detection was estimated to be 4.5x10(-9)M. The developed method is used for the determination of methylprednisolone in pharmaceutical dosages and human blood plasma samples of patients undergoing treatment with methylprednisolone. The major metabolites present in blood plasma did not interfere with the present investigation as they did not exhibit reduction peak in the experimental range used. A comparison of results with high performance liquid chromatography (HPLC) indicates a good agreement.

Effects of high-dose corticosteroids on post-traumatic inflammatory mediators.

OBJECTIVE: Plasma concentrations of inflammatory mediators are substantially increased in major orthopaedic surgery. It was our hypothesis that corticosteroids would reduce the post-operative levels of inflammatory mediators in patients with ankylosing spondylitis, and we performed a single-centre randomised controlled trial. PATIENTS AND METHODS: In 20 consecutive patients, an osteotomy of the lumbar spine was done. By concealed random allocation, 10 of the patients were given 10 mg/kg of methylprednisolone pre-operatively. The control patients received the same amount of saline. Samples of arterial blood and local blood from the surgical site were sampled and analysed for inflammatory cytokines and prostaglandin E2. RESULTS: There were significant increments in systemic levels of IL-6, IL-10 and sTNF-R1. Corticosteroids significantly reduced the increases of IL-6 and significantly increased the levels of IL-10 and sTNF-R1. Locally, the expressions of TNF-alpha, IL-1beta, IL-6 and sTNF-R1 were significantly increased in both groups post-operatively. Corticosteroids significantly increased the local expressions of IL-10 and sTNF-R1. There were significantly higher local than systemic levels of inflammatory mediators except for TNF-alpha. CONCLUSION: This study shows that in traumatic injury there are generally higher local than systemic expressions of inflammatory mediators, and that the main anti-inflammatory effects of high-dose corticosteroids are suppression of systemic IL-6 and increased expressions of IL-10 and sTNF-R1, both systemically and locally.