Vethe, Nils Tore PhD; Andersen, Anders Mikal BSc; Gedde-Dahl, Tobias MD, PhD; Büchner, Jochen MD, PhD; Bergan, Stein PhD Author Information

Background and aims: Statin-associated muscle symptoms (SAMS) is a prevalent cause of statin discontinuation. It is challenging and time-consuming for clinicians to assess whether symptoms are caused by the statin or not, and diagnostic biomarkers are requested. Atorvastatin metabolites have been associated with SAMS. We aimed to compare atorvastatin pharmacokinetics between coronary heart disease (CHD) patients with and without clinically statin intolerance and statin-dependent histopathological alterations in muscle tissue. Secondarily we aimed to assess genetic variants relevant for the observed pharmacokinetic variables. Methods: Twenty-eight patients with CHD and subjective SAMS were included in the exploratory MUSE biomarker study in 2020. Participants received atorvastatin 40 mg/day for seven weeks followed by no statins for eight weeks. Muscle biopsies and blood were collected at the end of each period. Four patients were categorized as clinically intolerant to >= 3 statins prior to study start whereas four patients had signs of muscle cell damage during treatment. Results: We found significantly lower levels of atorvastatin acids, and higher lactone/acid ratios in the statin intolerant, both in muscle and plasma. With optimal cut-off, the combination of 2-OH-atorvastatin acid and the 2-OH-atorvastatin lactone/acid ratio provided sensitivity, specificity, and predictive values of 100 %. Patients with variants in UGT1A1 and UGT1A3 had higher lactone metabolite levels than those with wild type, both in muscle and plasma. Conclusion: Atorvastatin metabolites appear promising as biomarkers for the identification of clinical statin intolerance in patients with self-perceived SAMS, but the findings have to be confirmed in larger studies.

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): Vestre Viken Hospital Trust. Background In clinical practice, it is challenging and time-consuming to assess whether self-perceived statin associated muscle symptoms (SAMS) are caused by the statin or not, and diagnostic biomarkers are therefore requested [1]. Atorvastatin (ATV) metabolites, especially the lactones, have been associated with statin dependent muscular side effects [2, 3]. Purpose To assess ATV metabolites as potential diagnostic biomarkers for statin dependent muscular side effects in skeletal muscle tissue and correspondingly in blood plasma among patients with coronary heart disease (CHD). Methods In 2020, an open biomarker follow-up study included 26 of 71 CHD patients with self-perceived SAMS who had participated in a randomised double-blinded crossover trial (ATV 40 mg/day and matched placebo) in 2019. Twelve participants reported significantly more symptoms during blinded treatment with ATV than during placebo, whereas the remaining 14 patients reported no differences in muscle symptoms between the treatment periods. In the biomarker study, all participants received open treatment with ATV 40 mg/day for seven weeks followed by no statins for eight weeks. Muscle biopsies were collected from the vastus lateralis of the quadriceps muscle after the ATV treatment period (n=26) and after the no-statin period (n=23). Blood was collected both pre-dose, at the time of biopsy (T0) and one hour after statin intake (T1). ATV and its five major metabolites were measured in muscle homogenate and blood plasma with liquid chromatography tandem mass spectrometry. A subgroup of four patients had histological signs of statin dependent muscle cell damage and three paitent did not tolerate any statins (n=2) or only pravastatin 20mg/day (n=1). These seven patients were categorised as having statin dependent muscular side effects. Mann-Whitney test and ROC-analyses were performed with SPSS. Results The lactone/acid ratios (ATV lactone/acid, 2OH-ATV lactone/acid, 4OH-ATV lactone/acid, sum lactones/sum acids) in muscle were all numerically higher in the seven patients than the rest. A similar pattern was found for plasma ratios at T0 and T1. The 2OH-ATV ratio and the sum ATV ratio in muscle were significantly different (p= 0.008 and p=0.022) between those with and without statin dependent side effects. The areas under the ROC curve (AUC) were 0.84 and 0.82, with sensitivity of 71% and 67%, and specificity of 90% and 94% (Table 1 and Figure 1). In plasma, the sum ATV ratio at T0 and T1 and the ATV lactone/acid ratio at T1 appeared as the best discriminators: with AUCs ranging from 0.74 to 0.83 and sensitivity and specificity estimates at 86% and 74%, respectively. Conclusions ATV lactone/acid ratios, measured in blood plasma one hour after atorvastatin intake, appear as promising biomarkers for statin dependent muscular side effects. Our study provides candidate cut-off values that should be pursued further for the determination of diagnostic sensitivity and specificity.

Self-perceived statin-associated muscle symptoms (SAMS) are prevalent, but only a minority is drug-dependent. Diagnostic biomarkers are not yet identified. The local statin exposure in skeletal muscle tissue may correlate to the adverse effects. We aimed to determine whether atorvastatin metabolites in blood reflect the corresponding metabolite levels in skeletal muscle, and whether genetic variants of statin transporters modulate this relationship. We also addressed atorvastatin metabolites as potential objective biomarkers of SAMS. Muscle symptoms were examined in patients with coronary disease and self-perceived SAMS during 7 weeks of double-blinded treatment with atorvastatin 40 mg/day and placebo in randomized order. A subset of 12 patients individually identified with more muscle symptoms on atorvastatin than placebo (confirmed SAMS) and 15 patients with no difference in muscle symptom intensity (non-SAMS) attended the present follow-up study. All received 7 weeks of treatment with atorvastatin 40 mg/day followed by 8 weeks without statins. Biopsies from the quadriceps muscle and blood plasma were collected after each treatment period. Strong correlations (rho > 0.7) between muscle and blood plasma concentrations were found for most atorvastatin metabolites. The impact of the SLCO1B1 c.521T>C (rs4149056) gene variant on atorvastatin's systemic pharmacokinetics was translated into muscle tissue. The SLCO2B1 c.395G>A (rs12422149) variant did not modulate the accumulation of atorvastatin metabolites in muscle tissue. Atorvastatin pharmacokinetics in patients with confirmed SAMS were not different from patients with non-SAMS. In conclusion, atorvastatin metabolite levels in skeletal muscle and plasma are strongly correlated, implying that plasma measurements are suitable proxies of atorvastatin exposure in muscle tissue. The relationship between atorvastatin metabolites in plasma and SAMS deserves further investigation.

AimsFinger‐prick sampling has emerged as an attractive tool for therapeutic drug monitoring and associated diagnostics. We aimed to validate the clinical performance of using two volumetric devices (Capitainer® qDBS and Mitra®) for monitoring tacrolimus, creatinine and haemoglobin in kidney transplant (KTx) recipients. Secondarily, we evaluated potential differences between finger‐prick sampling performed by healthcare professionals vs. self‐sampling, and differences between the two devices.MethodsWe compared finger‐prick and venous sampling in three settings: microsampling performed by healthcare personnel, self‐sampling under supervision, unsupervised self‐sampling. The finger‐prick samples were analysed with adapted methods and results compared to routine method analysis of the venous blood samples.ResultsTwenty‐five KTx recipients completed the main study and 12 KTx recipients completed a post hoc validation study. For tacrolimus measurements and predicted area under the curve, the proportions within ±20% difference were 79%–96% for Capitainer and 77%–95% for Mitra. For creatinine and haemoglobin, the proportions within ±15% were 92%–100% and 93%–100% for Capitainer and 79%–96% and 67%–92% for Mitra, respectively. Comparing sampling situations, the success rate was consistent for Capitainer (92%–96%), whereas Mitra showed 72%–88% and 52%–72% success rates with samples collected by healthcare personnel and the patients themselves.ConclusionsCapitainer and Mitra are technically feasible for measuring tacrolimus, creatinine and haemoglobin. In the context of self‐sampling, Capitainer maintained consistent sampling success and analytical quality. Implementing volumetric finger‐prick self‐sampling for the monitoring of tacrolimus, creatinine and haemoglobin may simplify and improve the follow‐up of KTx recipients.

Background: Poor statin adherence remains a public health concern associated with adverse outcomes. We evaluated the use of pharmacokinetic measurements to monitor adherence to simvastatin in patients with coronary heart disease (CHD). Methods: Eighteen patients with CHD taking an evening dose of simvastatin 20 mg (n = 7), 40 mg (n = 5), or 80 mg (n = 6) were examined at steady-state pharmacokinetics. Ten patients were instructed to interrupt simvastatin dosing and return for blood sampling for the subsequent 3 days. Dose-normalized plasma concentrations of simvastatin lactone and simvastatin acid and the sum of the 2 were evaluated to discriminate between adherent dosing and dose omission. Bioanalytical quantification was performed using liquid chromatography–tandem mass spectrometry. Results: A simvastatin acid cutoff of 1.0 × 10 −2 nmol −1 ·L −1 ·mg −1 identified 100% of those omitting 2 doses and 60% of those omitting a single dose. Simvastatin acid showed superior ability to discriminate dose omission, as well as the best agreement between samples handled at ambient and cool temperatures (median deviation 3.5%; interquartile range −2.5% to 13%). The cutoff for a morning dose schedule, with a similar ability to discriminate, was estimated at 2.0 × 10 −3 nmol −1 ·L −1 ·mg −1 . Conclusions: The present method discriminated between adherence and reduced adherence to simvastatin therapy in patients with CHD. Sample handling is feasible for routine practice, and the assessment of adherence can be performed by direct measurement of simvastatin acid in a blood sample, according to defined cutoff values. Further studies validating the cutoff value and utility for clinical application are encouraged.

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): National Association of Health OnBehalf NORCOR Background Poor adherence to statin therapy remains a public health concern associated with adverse clinical outcome. Reliable classification and detection of statin adherence is needed in clinical practice and for clinical studies with overall aim to improve the lipid management. Simvastatin is a frequently used statin in cardiovascular disease prevention. Purpose To develop a feasible test based on spot blood samples to monitor the adherence to simvastatin therapy in coronary heart disease (CHD) patients. Methods Eighteen CHD patients on an evening dose of simvastatin 20 mg (n = 7), 40 mg (n = 5) and 80 mg (n = 6) were studied at steady-state pharmacokinetics. Ten patients were instructed to avoid simvastatin dosing and return for blood sampling the subsequent three days. Dose-normalized plasma concentrations of simvastatin lactone, simvastatin acid and the sum of the two were evaluated as discriminators between adherent dosing and dose avoidance. Bioanalytical quantifications were performed with liquid chromatography tandem mass spectrometry. Results The dose-normalized plasma concentrations at steady-state demonstrated 23-fold and 39-fold interindividual variabilities for simvastatin lactone and simvastatin acid. A simvastatin acid cut-off at 1.0·10^-2 nmol/L/mg identified 100% of those omitting 2 doses and 60% of those omitting a single dose (Figure 1). Simvastatin acid showed superior ability to discriminate dose avoidance from adherence, and also the best agreement between samples handled at ambient and cool temperature (median deviation 3.5%, interquartile range -2.5 to 13%). A cut-off for morning dose schedule, with similar ability to discriminate, was estimated at 2.0·10^-3 nmol/L/mg. Conclusion A novel method discriminating between good and poor adherence to simvastatin therapy in CHD patients has been developed. The sample handling is feasible for routine practice, and the assessment of adherence can be performed by direct measurements in spot blood samples, according to specific cut-off values. Abstract Figure 1 Drug levels vs dose avoidance

A fast and reliable method based on two-channel liquid chromatography coupled to tandem mass spectrometry was developed and successfully validated for quantification of busulfan. The drug vehicle polyethylene glycol 400 was quantified simultaneously in patient samples. The sample preparation consisted of simple protein precipitation using a mixture of methanol and zinc sulphate containing busulfan-d8 as internal standard. Chromatographic separation was performed on a short biphenyl column (30 mm × 3.0 mm, 5 μm particles) using a step gradient from 30 % to 85 % methanol, ensuring co-elution of the analyte and internal standard. Quantification was performed using the mass transition of 264.1 > 151.1 for busulfan and 272.1 > 159.1 for the internal standard. Using only 20 μL of plasma sample, the lower limit of quantification was 25 ng/mL. Signal to noise ratio at the lower limit of quantification exceeded 300. The assay performance was not adversely affected by matrix effects originating from drug formulation excipients or other sample components. The coefficient of variation was ≤4 % and the mean accuracy 101–108 % across the calibration range 25–5 000 ng/mL. Chromatographic run time was 2 min and 8 s, allowing an effective run-time of 1 min and 10 s when using two alternating LC-channels. The assay has been implemented in routine practice with accreditation according to the ISO 15189 standard, and performs well in external quality control assessments. We present for the first time that shortly after an IV infusion of busulfan, the plasma levels of polyethylene glycol 400 may be in the range of 400−800 mg/L. The presence of these levels of detergent in patient samples may have detrimental effects on assay performance in LC–MS/MS, not limited to busulfan assays. This may be a concern for any LC–MS/MS analysis performed on samples collected within the first 24 h after an IV infusion of busulfan.

Pseudomyxoma peritonei (PMP) is a rare cancer commonly originating from appendiceal neoplasms that presents with mucinous tumor spread in the peritoneal cavity. Patients with PMP are treated with curative intent by cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). The value of adding HIPEC to CRS has not been proven in randomized trials, and the objective of this study was to investigate the efficacy of intraperitoneal mitomycin C (MMC) and regional hyperthermia as components of this complex treatment. Xenograft tissue established from a patient with histologically high-grade PMP with signet ring cell differentiation was implanted intraperitoneally in 65 athymic nude male rats and the animals were stratified into three treatment groups; the cytoreductive surgery group (CRSG, CRS only), the normothermic group (NG, CRS and intraperitoneal chemotherapy perfusion (IPEC) with MMC at 35 ºC), and the hyperthermic group (HG, CRS and IPEC at 41 ºC). The main endpoints were survival and tumor weight at autopsy. Adequate imitation of the clinical setting and treatment approach was achieved. The median survival was 31 days in the CRSG, 60 days in NG and 67 days in HG. The median tumor weights at autopsy were 34 g in CRSG, 23 g NG and 20 g in HG. In conclusion, the addition of IPEC with MMC after CRS doubled the survival time and reduced tumor growth compared to CRS alone. Adding regional hyperthermia resulted in a modest improvement of treatment outcome.

Because several steroid hormones are metabolized to their respective 6β-hydroxy forms by CYP3A4 and CYP3A5, these isoenzymes have been assumed to metabolize the immunosuppressive drug prednisolone, with conflicting results in the literature with respect to their relative importance. A direct study of the metabolism of prednisolone by microsomal CYP3A4 and CYP3A5 is missing. The aim of this in vitro study was to investigate the relative importance of recombinant CYP3A4 and recombinant CYP3A5 in the metabolism of prednisolone and to compare the extent of formation of 6β-OH-prednisolone by the two enzymes. Through in vitro incubations using rCYP3A4 and rCYP3A5 enzymes, intrinsic clearance (CLint ) of prednisolone was determined by the substrate depletion approach. Formation of the metabolite 6β-OH-prednisolone by rCYP3A4 and rCYP3A5, respectively, was compared. Prednisolone concentrations were measured, and its metabolite 6β-OH-prednisolone was identified using a HPLC-MS/MS in-house method. CLint for prednisolone by rCYP3A5 was less than 26% relative to rCYP3A4. Formation of 6β-OH-prednisolone by rCYP3A5 was less than 11% relative to rCYP3A4. The study indicates that 6β-hydroxylation of prednisolone assessed in vitro in recombinant CYP enzymes depends on rCYP3A4 rather than rCYP3A5 and that CYP3A5 may be responsible for the formation of other prednisolone metabolite(s) in addition to 6β-OH-prednisolone.

Background: Prednisolone (PL) is a standard component of most immunosuppressive protocols after solid organ transplantation (Tx). Adverse effects are frequent and well known. The aim of this study was to characterize the pharmacokinetics (PKs) of PL and prednisone (PN), including cortisol (CL) and cortisone (CN) profiles, after PL treatment in renal Tx recipients in the early post-Tx phase. Methods: This single-center, prospective, observational study included stable renal Tx recipients, >18 years of age, and in the early postengraftment phase. Blood samples were obtained predose and during a 24-hour dose interval [n = 26 samples per area under the curve (AUC0–24)], within the first 8 weeks post-Tx. PL, PN, CL, and CN concentrations were measured using high-performance liquid chromatography−tandem mass spectrometry. Results: In renal Tx recipients (n = 28), our results indicated a relatively high PL exposure [median, range AUC0–24 = 3821 (2232–5382) mcg h/L], paralleled by strong suppression of endogenous CL profile, demonstrated by a low CL evening-to-morning ratio [median, range 11 (3–47)%]. A negative correlation (r = −0.83) between PL AUC0–24 and morning CL levels was observed. The best single PK variable to predict PL AUC0–24 was PL C6 (r 2 = 0.82). An algorithm based on 3 PK sampling time points: trough, 2, and 4 hours after PL dosing, predicted PL AUC0–24 with a low percentage prediction error (PPE = 5.2 ± 1.5%) and a good correlation of determination (r 2 = 0.91). PL AUC0–24 varied 3-fold among study participants, whereas CL AUC0–24 varied by 18-fold. Conclusions: The large interindividual variability in both PL exposure and suppression of endogenous CL implies a possible role for therapeutic drug monitoring. An abbreviated profile within the first 4 hours after PL dosing provides a good prediction of PL exposure in renal Tx recipients. The strong negative correlation between PL AUC0–24 and morning CL levels suggests a possible surrogate marker for drug exposure for further evaluation.

AIMS:To explore the pharmacodynamics of mycophenolic acid (MPA) through inosine monophosphate dehydrogenase (IMPDH) capacity measurement and purine levels in peripheral blood mononuclear cells (PBMC) longitudinally during the first year after renal transplantation (TX). METHODS:PBMC were isolated from renal recipients 0-4 days prior to and 6-9 days, 5-7 weeks and 1 year after TX (before and 1.5 hours after dose). IMPDH capacity and purine (guanine and adenine) levels were measured in stimulated and nonstimulated PBMC. RESULTS:Twenty-nine patients completed the follow-up period, of whom 24 received MPA. In stimulated PBMC, the IMPDH capacity (pmol 10-6 cells min-1 ) was median (interquartile range) 127 (95.8-147) before TX and thereafter 44.9 (19.2-93.2) predose and 12.1 (4.64-23.6) 1.5 hours postdose across study days after TX. The corresponding IMPDH capacity in nonstimulated PBMC was 5.71 (3.79-6.93), 3.35 (2.31-5.62) and 2.71 (1.38-4.08), respectively. Predose IMPDH capacity in nonstimulated PBMC increased with time, reaching pre-TX values at 1 year. In stimulated PBMC, both purines were reduced before (median 39% reduction across days after TX) and after (69% reduction) dose compared to before TX. No alteration in the purine levels was observed in nonstimulated PBMC. Patients needing dose reductions during the first year had lower pre-dose IMPDH capacity in nonstimulated PBMC (1.87 vs 3.00 pmol 10-6 cells min-1 , P = .049) at 6-9 days. CONCLUSION:The inhibitory effect of MPA was stronger in stimulated PBMC. Nonstimulated PBMC became less sensitive to MPA during the first year after TX. Early IMPDH capacity appeared to be predictive of dose reductions.

Background: Therapeutic drug monitoring is standard practice for the immunosuppressant tacrolimus (Tac). Venous blood sampling at outpatient clinics is time-consuming and impractical with regard to obtaining trough concentrations on clinical visit days. Home-based blood sampling may be patient friendly and pave the way for limited sampling strategies for the prediction of total drug exposure. The aim was to establish a Tac assay for dried capillary microsamples, ensuring reliable measurements during the full dose interval in renal transplant recipients. Methods: An assay based on volumetric absorptive microsampling and liquid chromatography tandem mass spectrometry was validated. The agreement between capillary microsamples and liquid venous samples was investigated in stable renal recipients on twice-daily Tac dosing. Sampling throughout the 12-hour dose interval was examined at 2 separate days, at least 1 week apart, for each participant. Two sets of samples were obtained at each time point, one delivered directly to the laboratory and one sent through mail. Results: Twenty-seven renal transplant recipients were included, of whom 26 were investigated twice. Tac was efficiently extracted from the dried microsamples (mean recovery 94%-103%). The between-series mean accuracy was 88%-98% with coefficients of variation <= 5.0% (<= 11% at the lower limit of quantification), measurement range 0.70-60 mcg/L. The mean difference between parallel microsamples was 5%-7%. Overall, the mean differences between dried microsamples and liquid samples were -3.1% when mailed (n = 679) and -4.2% when directly delivered (n = 682). Less than 8% were outside +/- 20%. The microsamples were stable for 1 month at ambient temperature. Conclusions: The microsample method demonstrated acceptable performance. Tac concentrations can be reliably quantified throughout the dose interval by using volumetric absorptive microsampling in renal transplant recipients, and the results are not influenced by postal shipment.

Background: Low adherence to statin therapy remains a public health concern associated with poor prognosis in cardiovascular disease patients. A feasible method for statin adherence monitoring in clinical practice has yet to be developed. In this article, we describe a novel method designed for the direct monitoring of atorvastatin adherence based on the sum of parent drug and major metabolites in blood samples. Methods: Acid and lactone forms of atorvastatin, 2-OH-atorvastatin, and 4-OH-atorvastatin were assayed. Plasma proteins were precipitated with an acidified mixture of methanol, acetonitrile, and aqueous zinc sulfate, and the supernatant was analyzed with 2-channel reversed-phase chromatography coupled to tandem mass spectrometry. Assay validation was performed according to the guidelines provided by the European Medicines Agency and the US Food and Drug Administration. Results: The effective run time was 1 minute and 45 seconds per sample. Mean accuracy ranged from 92% to 110%, and coefficients of variation were ≤8.1% over the measurement ranges for individual compounds. The sum of acids and corresponding lactones was stable in clinical plasma samples kept at ambient temperature for up to 6 days after blood sampling (mean sum within 96.6%–101% of baseline). Conclusions A fast and reliable assay for the quantification of atorvastatin and its 5 major metabolites in clinical blood samples is reported. Limitations of preanalytical stability were solved using the sum of the acid and lactone forms. The assay is feasible for implementation in clinical practice, and the sum of parent drug and metabolites may be used for direct monitoring of atorvastatin adherence.

The Oslo Study of Clonidine in Elderly Patients with Delirium (LUCID) is an RCT investigating the effect of clonidine in medical patients > 65 years with delirium. To assess the dosage regimen and safety measures of this study protocol, we measured the plasma concentrations and hemodynamic effects of clonidine in the first 20 patients.

Background: Tacrolimus (TAC) is currently the cornerstone of immunosuppressive protocols for renal transplant recipients. Despite therapeutic whole blood monitoring, TAC is associated with nephrotoxicity, and it has been hypothesized that intrarenal accumulation of TAC and/or its metabolites are involved. As TAC is a substrate of P-glycoprotein (P-gp), the expression and activity of this efflux transporter could influence the levels of TAC in renal tissue. The primary aim of this study was to develop and validate a method for quantification of TAC in tissue homogenates from single human renal core biopsies. The secondary aim was to provide measures of P-gp expression and of the demethylated metabolites of TAC in the same renal biopsy. Methods: Human renal tissue, with and without clinical TAC exposure, was used for method development and validation. Homogenates were prepared with bead-beating, and concentrations of TAC and its demethylated metabolites were analyzed with liquid chromatography tandem mass spectrometry after protein precipitation. A Western blot method was used for semiquantification of P-gp expression in the homogenates. The final methods were applied to renal core biopsies from 2 transplant patients. Results: The TAC assay showed within- and between-run mean accuracy between 99.7% and 107% and coefficients of variation ≤6.7%. Matrix effects were nonsignificant, and samples were stable for 3 months preanalytically when stored at −80°C. TAC concentrations in the renal core biopsies were 62.6 and 43.7 pg/mg tissue. The methods for measurement of desmethyl-TAC and P-gp expression were suitable for semiquantification in homogenates from renal core biopsies. Conclusions: These methods may be valuable for the elucidation of the pharmacokinetic mechanisms behind TAC-induced nephrotoxicity in renal transplant recipients.

Introduction: Tacrolimus (TAC) is an immunosuppressive drug used after organ transplantation. Dosing is adjusted using whole blood (WB-TAC) measurements. Patients within the therapeutic WB-TAC window still experience rejections and adverse effects. Alternative monitoring methods are therefore warranted. The authors developed a method for measuring TAC in peripheral blood mononuclear cell (PBMC) isolates (PBMC-TAC) and performed a pharmacokinetic study in a cohort of kidney transplant patients during the first year after transplantation. Methods: PBMCs were isolated from whole blood by gradient centrifugation. After methanol-based extraction, liquid chromatography with tandem mass spectrometry was used to determine TAC in the extract. PBMC-TAC was normalized to the number of cells and alternatively to the protein amount in cells. Predose and postdose (1.5 hours) samples from kidney transplant patients were collected at 1 week, 6 weeks, and 1 year after transplantation. WB-TAC was measured using immunoassay. Results: The PBMC-TAC assay fulfilled the validation criteria of the European Medicines Agency guidelines. Twenty-nine patients completed the study. Predose PBMC-TAC was (median) 23 (1 week), 33 (6 weeks), and 27 pg/106 cells (1 year). Postdose PBMC-TAC was 44, 30, and 27 pg/106 cells at 1 week, 6 weeks, and 1 year after transplantation, respectively. Predose WB-TAC (median) was 5.0, 6.0, and 5.4 mcg/L, and postdose WB-TAC was 10.5, 8.3, and 9.1 mcg/L, respectively, at 1 week, 6 weeks, and 1 year after transplantation. Whole blood and PBMC-TAC correlated at all timepoints (rho 0.40–0.82, P < 0.05) except before dosage at 6 weeks. PBMC-TAC normalized to the number of cells, and the amount of protein was modestly correlated (rho 0.36–0.81, P < 0.056). Conclusions: The correlation between WB-TAC and PBMC-TAC is modest during the first-year posttransplantation. Normalization of PBMC-TAC to cells or protein may yield different results. PBMC-TAC is increased 1.5 hours after dose at 1 week after transplantation, but not after 6 weeks or 1 year, indicating altered distribution kinetics.

Chronic Fatigue Syndrome (CFS) is a common and disabling condition in adolescence with few treatment options. A central feature of CFS is orthostatic intolerance and abnormal autonomic cardiovascular control characterized by sympathetic predominance. We hypothesized that symptoms as well as the underlying pathophysiology might improve by treatment with the alpha2A–adrenoceptor agonist clonidine.

IMPORTANCE Chronic fatigue syndrome (CFS) is a disabling condition with unknown disease mechanisms and few treatment options. OBJECTIVE To explore the pathophysiology of CFS and assess clonidine hydrochloride pharmacotherapy in adolescents with CFS by using a hypothesis that patients with CFS have enhanced sympathetic activity and that sympatho-inhibition by clonidine would improve symptoms and function. DESIGN, SETTING, AND PARTICIPANTS Participants were enrolled from a single referral center recruiting nationwide in Norway. A referred sample of 176 adolescents with CFS was assessed for eligibility; 120 were included (34 males and 86 females; mean age, 15.4 years). A volunteer sample of 68 healthy adolescents serving as controls was included (22 males and 46 females; mean age, 15.1 years). The CSF patients and healthy controls were assessed cross-sectionally at baseline. Thereafter, patients with CFS were randomized 1:1 to treatment with low-dose clonidine or placebo for 9 weeks and monitored for 30 weeks; double-blinding was provided. Data were collected from March 2010 until October 2012 as part of the Norwegian Study of Chronic Fatigue Syndrome in Adolescents: Pathophysiology and Intervention Trial. INTERVENTIONS Clonidine hydrochloride capsules (25 µg or 50 µg twice daily for body weight <35 kg or >35 kg, respectively) vs placebo capsules for 9 weeks. MAIN OUTCOMES AND MEASURES Number of steps per day. RESULTS At baseline, patients with CFS had a lower number of steps per day (P < .001), digit span backward score (P = .002), and urinary cortisol to creatinine ratio (P = .001), and a higher fatigue score (P < .001), heart rate responsiveness (P = .02), plasma norepinephrine level (P < .001), and serum C-reactive protein concentration (P = .04) compared with healthy controls. There were no significant differences regarding blood microbiology evaluation. During intervention, the clonidine group had a lower number of steps per day (mean difference, -637 steps; P = .07), lower plasma norepinephrine level (mean difference, -42 pg/mL; P = .01), and lower serum C-reactive protein concentration (mean ratio, 0.69; P = .02) compared with the CFS placebo group. CONCLUSIONS AND RELEVANCE Adolescent CFS is associated with enhanced sympathetic nervous activity, low-grade systemic inflammation, attenuated hypothalamus-pituitary-adrenal axis function, cognitive impairment, and large activity reduction, but not with common microorganisms. Low-dose clonidine attenuates sympathetic outflow and systemic inflammation in CFS but has a concomitant negative effect on physical activity; thus, sympathetic and inflammatory enhancement may be compensatory mechanisms. Low-dose clonidine is not clinically useful in CFS. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01040429.

Background and ObjectivesPatients with peritoneal surface malignancies are treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy, commonly using mitomycin C (MMC). The purpose of this study was to investigate impact of hyperthermia on pharmacokinetics of intraperitoneal MMC.MethodsIn 14 athymic nude male rats, microdialysis (MD) probes were implanted in jugular vein (V), hind leg muscle (M) and extraperitoneal space (XP). Probes were calibrated by retrodialysis. Intraperitonal chemotherapy perfusion (IPEC) was administered over 90 min with MMC 5 mg/kg and saline 0.9% 500 ml/kg at 35 and 41°C, defining the normothermic (NG) and hyperthermic groups (HG), respectively. MD and peritoneal perfusion fluid (PPF) samples were collected at 10 min intervals to determine MMC concentration.ResultsTime–concentration curves were virtually parallel between temperature groups, with equal peak concentrations (µM) of 0.3 (V), 0.7 (XP) and 0.3 (M). The following area under time–concentration curve (AUC) ratios were calculated: AUC PPF/AUC V were 69 in NG and 79 in HG (P = 0.54); AUC XP/AUC V were 2.7 in NG and 2.6 in HG (P = 0.90).ConclusionsIPEC provides high intraperitoneal MMC concentration and increased bioavailability in extraperitoneal tissue, combined with low systemic absorption. Hyperthermia at 41°C did not modify MMC pharmacokinetics. J. Surg. Oncol. 2014 109:521–526. © 2013 Wiley Periodicals, Inc.