The atorvastatin metabolite pattern in muscle tissue and blood plasma is associated with statin muscle side effects in patients with coronary heart disease; An exploratory case-control study

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.

Validation of a novel direct method to determine reduced adherence to atorvastatin therapy

AIMS

Objective methods to determine statin adherence are requested to improve lipid management. We have recently established a method to detect reduced adherence to atorvastatin therapy with cut-off values based on the sum of atorvastatin and its major metabolites in blood. We aimed to validate this method in patients with and without cardiovascular disease, and optimize previous cut-off values.

METHODS AND RESULTS

The pharmacokinetic study included 60 participants treated with atorvastatin 20 mg (N=20), 40 mg (N=20), and 80 mg (N=20). Atorvastatin was then stopped and blood samples collected from day zero to day four. Quantification of the parent drug and its metabolites in blood plasma was performed with a liquid chromatography-tandem mass spectrometry assay. The cut-off values for reduced adherence were validated and optimized by calculating diagnostic sensitivity and specificity. Our candidate cut-off value of dose-normalized six-component sum of atorvastatin plus metabolites <0.10 nM/mg provided a sensitivity of 97% and a specificity of 93% for detecting ≥2 omitted doses. An optimized cut-off <0.062 nM/mg provided a sensitivity of 90% and a specificity of 100%. An alternative simplified two-component metabolite sum with cut-off value <0.05 nM/mg provided a sensitivity of 98% and a specificity of 76%. An optimized cut-off <0.02 nM/mg provided a sensitivity of 97% and a specificity of 98%.

CONCLUSION

This validation study confirms that our direct method discriminates reduced adherence from adherence to atorvastatin therapy with high diagnostic accuracy. The method may improve lipid management in clinical practice and serve as a useful tool in future studies.

Clinical performance of volumetric finger-prick sampling for the monitoring of tacrolimus, creatinine and haemoglobin in kidney transplant recipients

AIMS

Finger-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.

METHODS

We 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.

RESULTS

Twenty-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.

CONCLUSIONS

Capitainer 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.

Plasma concentration of atorvastatin metabolites correlates with low-density lipoprotein cholesterol reduction in patients with coronary heart disease

In this exploratory study from a randomized double-blinded crossover trial including 70 patients with coronary heart disease and self-perceived muscular side effects of statins, we aimed to determine the relationship between low-density lipoprotein cholesterol (LDL-C) reduction and atorvastatin metabolite plasma concentrations. All patients underwent a 7 weeks treatment period with atorvastatin 40 mg/day and a 7 weeks placebo period in random order. Nonlinear regression with a three-parameter equation explored the relationship between percentage LDL-C reduction (statin vs. placebo) and the pharmacokinetic variables. Mean LDL-C reduction was 49% (range 12% to 71%). The sum of 4-OH-atorvastatin acid and lactone correlated moderately with the LDL-C response (Spearman ρ 0.27, 95% confidence interval [CI]: 0.03 to 0.48). Accordingly, nonlinear regression showed R² of 0.14 (95% CI: 0.03 to 0.37, R² adjusted equaled 0.11). Even a perfect underlying correlation of 1.0 showed R²  = 0.32 by simulation, using historical intra-individual LDL-C variation (8.5%). The 90% inhibitory concentration was 2.1 nmol/L, and the 4-OH-metabolite sum exceeded this threshold in 34% of the patients. In conclusion, trough plasma concentrations of 4-OH-atorvastatin metabolites correlated moderately to the LDL-C reduction. A plateau LDL-C response was observed above a pharmacokinetic threshold, below which the response was highly variable. The usefulness of monitoring concentrations of atorvastatin metabolites to optimize the individual dosage have limitations, but its supportive potential may be pursued in relevant patient subsets to achieve adequate efficacy at the lowest possible dose. The results add knowledge to the overall understanding of the variable LDL-C response mediated by atorvastatin.

Atorvastatin Metabolite Pattern in Skeletal Muscle and Blood from Patients with Coronary Heart Disease and Statin-Associated Muscle Symptoms

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.

Monitoring Simvastatin Adherence in Patients With Coronary Heart Disease: A Proof-of-Concept Study Based on Pharmacokinetic Measurements in Blood Plasma

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.

Low-density lipoprotein cholesterol increased significantly after short-term discontinuation of atorvastatin, but did not correlate with plasma drug concentrations

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): The Dam foundation

Introduction

Statin non-adherence remains a prevalent challenge in cardiovascular disease prevention and robust methods to monitor adherence are needed. Large variations in low-density-lipoprotein cholesterol (LDL-C) response to a given type and dose of statin have been reported. The LDL-C response to short-term discontinuation of statins is not well defined. Moreover, the relationship between the blood concentrations of statin metabolites and LDL-C, and how clinical factors interact, are unknown.

Purpose

To determine changes in LDL-C at an individual and group level during four-day discontinuation of atorvastatin, and to investigate whether clinical factors and atorvastatin metabolites concentration correlate with changes in LDL-C.

Methods

This clinical pharmacokinetic adherence study conducted in 2021, included 60 adult participants treated with atorvastatin 20 mg (n=20), 40 mg (n=20) or 80 mg (n=20). The participants were instructed to take atorvastatin daily between 07 and 10 am the week before study start, to ensure steady state drug concentrations. The last dose of atorvastatin was taken 24 hours prior to the first blood sampling (day zero). Atorvastatin doses were omitted until after blood sampling on the fourth day. The concentrations of atorvastatin metabolites (acid and lactone forms, including 2-OH- and 4-OH metabolite) were measured by a liquid chromatography–tandem mass spectrometry assay. Paired-samples T-tests, Spearman rank correlations and linear regression analyses were performed with SPSS.

Results

Mean age was 65 (SD 11) years, 18 (30%) were female, 45 (75%) had cardiovascular disease and 11 (18%) had diabetes mellitus. Mean LDL-C at steady state on day zero was 1.9 (SD 0.6) mmol/L. LDL-C increased on average by 0.5 (SD 0.3) mmol/L (30%) from day zero to day four, during the period with atorvastatin discontinuation. The increase of LDL-C was significant already after the first omitted dose (day one) (Figure 1). LDL-C increased from day zero to day four in 78 out of the 80 patients (97.5%). Higher Body Mass Index was significantly associated with lager increase in LDL-C during the four-day discontinuation (B 0.02, 95% CI 0.01 to 0.04, p=0.028), whereas age, sex, kidney function, cardiovascular disease and diabetes were not. Changes in atorvastatin plus metabolites concentration from day zero to day four were not associated with changes in LDL-C during discontinuation (Figure 2). This also applied if we assessed the individual atorvastatin metabolites.

Conclusion

Atorvastatin discontinuation for only four days resulted in a statistically significant 30% increase of LDL-C. Atorvastatin pharmacokinetics did not correlate with change in LDL-C during the discontinuation. Even short-term non-adherence may have unfavourable consequences, and deserves further attention.

Clinical and psychological factors in coronary heart disease patients with statin associated muscle side-effects

Background

To compare clinical and psychological factors among patients with self-perceived statin-associated muscle symptoms (SAMS), confirmed SAMS, and refuted SAMS in coronary heart disease patients (CHD).

Methods

Data were obtained from a cross-sectional study of 1100 CHD outpatients and a study of 71 CHD outpatients attending a randomized, double-blinded, placebo-controlled, crossover study to test effects of atorvastatin 40 mg/day on muscle symptom intensity. Clinical and psychosocial factors were compared between patients with and without SAMS in the cross-sectional study, and between patients with confirmed SAMS and refuted SAMS in the randomized study.

Results

Bilateral, symmetric muscle symptoms in the lower extremities during statin treatment were more prevalent in patients with confirmed SAMS compared to patients with refuted SAMS (75% vs. 41%, p = 0.01) in the randomized study. No significant differences in psychological factors (anxiety, depression, worry, insomnia, type D personality characteristics) were detected between patients with and without self-perceived SAMS in the cross-sectional study, or between patients with confirmed SAMS and refuted SAMS, in the randomized study.

Conclusions

Patients with confirmed SAMS more often present with bilateral lower muscle symptoms compared to those with refuted SAMS. Psychological factors were not associated with self-perceived SAMS or confirmed SAMS. A careful pain history and a search for alternative causes of muscle symptoms are likely to promote communication in patients with SAMS, and may reduce the risk for statin discontinuation.

Effect of atorvastatin on muscle symptoms in coronary heart disease patients with self-perceived statin muscle side effects: a randomized, double-blinded crossover trial

AIMS

To estimate the effect of atorvastatin on muscle symptom intensity in coronary heart disease (CHD) patients with self-perceived statin-associated muscle symptoms (SAMS) and to determine the relationship to blood levels of atorvastatin and/or metabolites.

METHODS AND RESULTS

A randomized multi-centre trial consecutively identified 982 patients with previous or ongoing atorvastatin treatment after a CHD event. Of these, 97 (9.9%) reported SAMS and 77 were randomized to 7-week double-blinded treatment with atorvastatin 40 mg/day and placebo in a crossover design. The primary outcome was the individual mean difference in muscle symptom intensity between the treatment periods, measured by visual-analogue scale (VAS) scores. Atorvastatin did not affect the intensity of muscle symptoms among 71 patients who completed the trial. Mean VAS difference (statin-placebo) was 0.31 (95% CI: -0.24 to 0.86). The proportion with more muscle symptoms during placebo than atorvastatin was 17% (n = 12), 55% (n = 39) had the same muscle symptom intensity during both treatment periods whereas 28% (n = 20) had more symptoms during atorvastatin than placebo (confirmed SAMS). There were no differences in clinical or pharmacogenetic characteristics between these groups. The levels of atorvastatin and/or metabolites did not correlate to muscle symptom intensity among patients with confirmed SAMS (Spearman's rho ≤0.40, for all variables).

CONCLUSION

Re-challenge with high-intensity atorvastatin did not affect the intensity of muscle symptoms in CHD patients with self-perceived SAMS during previous atorvastatin therapy. There was no relationship between muscle symptoms and the systemic exposure to atorvastatin and/or its metabolites. The findings encourage an informed discussion to elucidate other causes of muscle complaints and continued statin use.

The relationship between directly measured statin adherence, self-reported adherence measures and cholesterol levels in patients with coronary heart disease

BACKGROUND AND AIMS

We aimed to determine the relationship between statin adherence measured directly, and by self-report measures and serum cholesterol levels.

METHODS

Patients prescribed atorvastatin (N = 373) participated in a cross-sectional study 2-36 months after a coronary event. Self-reported adherence included statin adherence the past week, the 8-item Morisky medication adherence scale (MMAS-8), and the Gehi et al. adherence question. Atorvastatin was measured directly in spot blood plasma by a novel liquid chromatography tandem mass-spectrometry method discriminating adherence (0-1 doses omitted) and reduced adherence (≥2 doses omitted). Participants were unaware of the atorvastatin analyses at study participation.

RESULTS

Mean age was 63 (SD 9) years and 8% had reduced atorvastatin adherence according to the direct method. In patients classified with reduced adherence by the direct method, 40% reported reduced statin adherence, 32% reported reduced adherence with the MMAS-8 and 22% with the Gehi question. In those adherent by the direct method, 96% also reported high statin adherence, 95% reported high adherence on the MMAS-8 whereas 94% reported high adherence on the Gehi question. Cohen's kappa agreement score with the direct method was 0.4 for self-reported statin adherence, 0.3 for the Gehi question and 0.2 for the MMAS-8. Adherence determined by the direct method, self-reported statin adherence last week, and the Gehi question was inversely related to LDL-cholesterol levels with a p-value of <0.001, 0.001 and 0.004, respectively.

CONCLUSIONS

Plasma-statin measurements reveal reduced adherence with higher sensitivity than self-report measures, relate to cholesterol levels, and may prove to be a useful tool to improve lipid management.

In vitro assessments predict that CYP3A4 contributes to a greater extent than CYP3A5 to prednisolone clearance

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 (CL_int ) of prednisolone was determined by the substrate depletion approach. Formation of the metabolite 6β-OH-prednisolone by rCYP3A4 and rCYP3A5, respectively, were compared. Prednisolone concentrations were measured and its metabolite 6β-OH-prednisolone was identified using a HPLC-MS/MS in-house method. CL_int 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.

Tacrolimus Measured in Capillary Volumetric Microsamples in Pediatric Patients-A Cross-Validation Study

BACKGROUND

Therapeutic drug monitoring of tacrolimus (Tac) is mandatory in solid organ transplant (SOT) recipients. Finger-prick microsampling is more flexible and tolerable during the therapeutic drug monitoring of tacrolimus and has been shown to be applicable in adult SOT recipients. In this study, a previously validated method applying volumetric absorptive microsampling (VAMS) to measure Tac in adults was cross-validated in a pediatric population.

METHODS

Patients with SOT scheduled for standard posttransplant follow-up visits were recruited. Blood samples were obtained by trained phlebotomists using standard venipuncture and capillary microsampling, before the morning dose of Tac as well as 2 and 5 hours after dosing. Tac concentrations were quantified using liquid chromatography-tandem mass spectrometry. Concordance between Tac concentrations obtained with venipuncture and VAMS was evaluated using Passing-Bablok regression, calculation of absolute and relative differences, and percentage of samples within ±20% and ±30% difference.

RESULTS

A total of 39 SOT patients aged 4-18 years (22 male) were included. The median (range) predose venous blood concentration was 4.8 (2.6-13.6) mcg/L, with a difference between VAMS and venous blood samples of -0.2 ± 0.7 mcg/L. The relative mean difference was -1.3% [95% confidence interval (CI), -5.9% to 3.4%]. Ninety-two percent and 97% of the sample pairs demonstrated differences within ±20% and ±30%, respectively. Postdose (2 hours and/or 5 hours, n = 17) median concentration in venous blood was 7.9 (4.8-19.2) mcg/L. The difference between VAMS and venous blood samples was 0.1 ± 1.0 mcg/L, with a relative mean difference of -2.5% (95% confidence interval, -8.8% to 3.8%). Eighty-eight percent of the postdose sample pairs were within ±20% difference, and all were within ±30% difference.

CONCLUSIONS

Tac concentrations can be accurately measured using VAMS technology in pediatric SOT recipients. This makes home-based Tac monitoring feasible in the pediatric population.

Tailored clinical management after blinded statin challenge improved long-term lipid control in coronary patients with self-perceived muscle side-effects

Funding Acknowledgements

Type of funding sources: Public hospital(s). Main funding source(s): Helse Sør-Øst, Vestre Viken Trust

Background

Statin discontinuation due to self-perceived muscle side-effects is a major challenge in clinical practice. Strategies are needed to improve lipid control in these patients.

Purpose

We studied if information about the results of a blinded statin challenge experiment, followed by tailored lipid lowering treatment, had long-term effects on lipid control in coronary patients with self-perceived muscle side-effects.

Methods

A post-trial intervention study of patients classified with statin dependent (N = 20) and independent (N = 50) muscle complaints in the MUscle Side-Effects of atorvastatin (MUSE), a randomized, double-blinded, crossover trial. All participants were informed of the MUSE trial results in an individual consultation and provided tailored lipid-lowering treatment according to protocol with 1-2 follow-up calls. Lipids were controlled at the end of follow-up.

Results

Mean age was 64 (SD 9.5) years and 33% (N = 23) were females. During an average follow-up of 13 months (SD 3.3), mean LDL-cholesterol was reduced by 0.3 (SD 0.6) mmol/L (p = 0.005) in patients with statins and by 1.7 (SD 1.0) mmol/L (p = 0.005) in patients without statins at inclusion in the MUSE trial (Table). We found no changes in the overall use of high-intensity statins, but ezetimibe was used by 11 additional patients and 4 patients were prescribed a PCSK9-inhibitor. Participants in the subgroup without statins at inclusion used; atorvastatin (N = 2), rosuvastatin (N = 3) or a PCSK9-inhibitor (N = 2) at follow-up. 90% found their own trial results useful in making decisions about future statin use.

Conclusions

Information about the results of a statin challenge experiment combined with tailored and systematical prescription of lipid-lowering agents had favourable long-term effects on lipid control in coronary patients with self-perceived muscle side-effects.

Characteristics of the study population Using statins at inclusion (n = 62) Not using statins at inclusion (n = 8) Classified with statin-dependent side-effects, n (%) 15 (24) 5 (63) LDL-cholesterol at inclusion, mean (SD) 2.2 (0.8) 4.2 (1.1) LDL-cholesterol at follow-up, mean (SD) 1.9 (0.7) 2.5 (0.8) High intensity statin (ie. ≥40 mg atorvastatin or ≥20 mg rosuvastatin) at inclusion, n (%) 40 (55.6) 0 (0) High intensity statin at follow-up, n (%) 38 (61) 2 (25) Ezetimibe at inclusion, n (%) 13 (21) 3 (38) Ezetimibe at follow-up, n (%) 26 (42) 1 (13) PCSK-9 inhibitor at follow-up, n (%) 2 (3) 2 (25) Usefulness of own trial result in making decisions about future statin use on a 0 to 10 Likert scale, mean (SD) 8.1 (2.0) 9.6 (0.6)

High but not low self-reported statin adherence was confirmed by a novel method based on plasma-statin measurements in coronary outpatients

Funding Acknowledgements

Type of funding sources: Public hospital(s). Main funding source(s): Helse Sør-Øst

Background

To what extent self-reported adherence measures correspond with directly measured statin adherence is unknown.

Purpose

 To determine the relationship between, self-reported adherence measures, low density lipoprotein-cholesterol (LDL-C) and directly measured statin adherence in coronary outpatients.

Methods

Patients on atorvastatin (N = 373) participated in a cross-sectional study median 16 months after a coronary event. Adherence to statins the past 7 days, general medication adherence assessed by the 8-item Morisky medication adherence scale (MMAS-8), and the Gehi adherence question was obtained by a self-report questionnaire. Atorvastatin was determined in spot blood plasma samples by a novel liquid-chromatography tandem mass-spectrometry method discriminating between adherence (0-1 doses omitted) and reduced (≥2 doses omitted) adherence. Participants were unaware of the atorvastatin analyses at study participation. 

Results

Mean age was 63 (SD 9) years and 19% were females. Mean atorvastatin dose was 64 (SD 21) mg. The number with reduced adherence by the different measurement methods, Cohens kappa agreement score between the self-reported and direct adherence measures, and LDL-C are shown in the Table. Statin adherence was confirmed by the direct method among 96% reporting high statin adherence the past 7 days, among 95% reporting high adherence on the MMAS-8 and among 94% reporting high adherence on the Gehi adherence question. In contrast, among patients classified with reduced statin adherence by the direct method, only 40% reported reduced statin adherence the past week, 32% reported reduced adherence with the MMAS-8 and 22% with the Gehi adherence question.

Conclusions

The direct method confirmed high, but not low, self-reported statin adherence in this selected sample of coronary outpatients. In patients with elevated LDL-cholesterol, plasma-statin measurements emerges as a potential improvement for clinical statin management.

Adherence measures and LDL cholesterol Directly measured atorvastatin adherence Self-reported statin adherence past 7 days Self-reported medication adherence past month (Gehi) 8-item Morisky medication adherence scale Number with reduced adherence, % 7.8 5.5 3.0 8.4 Cohen"s kappa (95% CI) Reference 0.4 (0.2 to 0.6) 0.3 (0.1 to 0.5) 0.2 (0.1 to 0.4) LDL-C, Adherent, mean (95% CI) 1.9 (1.8 to 1.9) 1.9 (1.8 to 2.0) 1.9 (1.8 to 2.0) 1.9 (1.8 to 1.9) LDL-C, Reduced adherence, mean (95% CI) 2.8 (2.4 to 3.2) 2.8 (2.3 to 3.2) 3.2 (2.5 to 3.8) 2.1 (1.9 to 2.4) LDL-C, Adherent versus reduced adherence P &lt;0.001 P = 0.001 P = 0.004 P = 0.07 Agreement between directly measured atorvastatin adherence, self-reported measures of adherence, and mean low density lipoprotein-cholesterol (LDL-C)

Personalized Therapy for Mycophenolate: Consensus Report by the International Association of Therapeutic Drug Monitoring and Clinical Toxicology

ABSTRACT

When mycophenolic acid (MPA) was originally marketed for immunosuppressive therapy, fixed doses were recommended by the manufacturer. Awareness of the potential for a more personalized dosing has led to development of methods to estimate MPA area under the curve based on the measurement of drug concentrations in only a few samples. This approach is feasible in the clinical routine and has proven successful in terms of correlation with outcome. However, the search for superior correlates has continued, and numerous studies in search of biomarkers that could better predict the perfect dosage for the individual patient have been published. As it was considered timely for an updated and comprehensive presentation of consensus on the status for personalized treatment with MPA, this report was prepared following an initiative from members of the International Association of Therapeutic Drug Monitoring and Clinical Toxicology (IATDMCT). Topics included are the criteria for analytics, methods to estimate exposure including pharmacometrics, the potential influence of pharmacogenetics, development of biomarkers, and the practical aspects of implementation of target concentration intervention. For selected topics with sufficient evidence, such as the application of limited sampling strategies for MPA area under the curve, graded recommendations on target ranges are presented. To provide a comprehensive review, this report also includes updates on the status of potential biomarkers including those which may be promising but with a low level of evidence. In view of the fact that there are very few new immunosuppressive drugs under development for the transplant field, it is likely that MPA will continue to be prescribed on a large scale in the upcoming years. Discontinuation of therapy due to adverse effects is relatively common, increasing the risk for late rejections, which may contribute to graft loss. Therefore, the continued search for innovative methods to better personalize MPA dosage is warranted.

Fasting Status and Circadian Variation Must be Considered When Performing AUC-based Therapeutic Drug Monitoring of Tacrolimus in Renal Transplant Recipients

Therapeutic drug monitoring (TDM) is mandatory for the immunosuppressive drug tacrolimus (Tac). For clinical applicability, TDM is performed using morning trough concentrations. With recent developments making tacrolimus concentration determination possible in capillary microsamples and Bayesian estimator predicted area under the concentration curve (AUC), AUC‐guided TDM may now be clinically applicable. Tac circadian variation has, however, been reported, with lower systemic exposure following the evening dose. The aim of the present study was to investigate tacrolimus pharmacokinetic (PK) after morning and evening administrations of twice‐daily tacrolimus in a real‐life setting without restrictions regarding food and concomitant drug timing. Two 12 hour tacrolimus investigations were performed; after the morning dose and the following evening dose, respectively, in 31 renal transplant recipients early after transplantation both in a fasting‐state and under real‐life nonfasting conditions (14 patients repeated the investigation). We observed circadian variation under fasting‐conditions: 45% higher peak‐concentration and 20% higher AUC following the morning dose. In the real‐life nonfasting setting, the PK‐profiles were flat but comparable after the morning and evening doses, showing slower absorption rate and lower AUC compared with the fasting‐state. Limited sampling strategies using concentrations at 0, 1, and 3 hours predicted AUC after fasting morning administration, and samples obtained at 1, 3, and 6 hours predicted AUC for the other conditions (evening and real‐life nonfasting). In conclusion, circadian variation of tacrolimus is present when performed in patients who are in the fasting‐state, whereas flatter PK‐profiles and no circadian variation was present in a real‐life, nonfasting setting.

Pharmacodynamic assessment of mycophenolic acid in resting and activated target cell population during the first year after renal transplantation

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.

Comparing the Effects of the mTOR Inhibitors Azithromycin and Rapamycin on In Vitro Expanded Regulatory T Cells

Adoptive transfer of autologous polyclonal regulatory T cells (Tregs) is a promising option for reducing graft rejection in allogeneic transplantation. To gain therapeutic levels of Tregs there is a need to expand obtained cells ex vivo, usually in the presence of the mTOR inhibitor Rapamycin due to its ability to suppress proliferation of non-Treg T cells, thus promoting a purer Treg yield. Azithromycin is a bacteriostatic macrolide with mTOR inhibitory activity that has been shown to exert immunomodulatory effects on several types of immune cells. In this study we investigated the effects of Azithromycin, compared with Rapamycin, on Treg phenotype, growth, and function when expanding bulk, naïve, and memory Tregs. Furthermore, the intracellular concentration of Rapamycin in CD4+ T cells as well as in the culture medium was measured for up to 48 h after supplemented. Treg phenotype was assessed by flow cytometry and Treg function was measured as inhibition of responder T-cell expansion in a suppression assay. The concentration of Rapamycin was quantified with liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Azithromycin and Rapamycin both promoted a FoxP3-positive Treg phenotype in bulk Tregs, while Rapamycin also increased FoxP3 and FoxP3+Helios positivity in naïve and memory Tregs. Furthermore, Rapamycin inhibited the expansion of naïve Tregs, but also increased their suppressive effect. Rapamycin was quickly degraded in 37°C medium, yet was retained intracellularly. While both compounds may benefit expansion of FoxP3+ Tregs in vitro, further studies elucidating the effects of Azithromycin treatment on Tregs are needed to determine its potential use.

BEtablocker Treatment After acute Myocardial Infarction in revascularized patients without reduced left ventricular ejection fraction (BETAMI): Rationale and design of a prospective, randomized, open, blinded end point study

BACKGROUND

Current guidelines on the use of β-blockers in post-acute myocardial infarction (MI) patients without reduced left ventricular ejection fraction (LVEF) are based on studies before the implementation of modern reperfusion and secondary prevention therapies. It remains unknown whether β-blockers will reduce mortality and recurrent MI in contemporary revascularized post-MI patients without reduced LVEF.

DESIGN

BETAMI is a prospective, randomized, open, blinded end point multicenter study in 10,000 MI patients designed to test the superiority of oral β-blocker therapy compared to no β-blocker therapy. Patients with LVEF ≥40% following treatment with percutaneous coronary intervention or thrombolysis and/or no clinical signs of heart failure are eligible to participate. The primary end point is a composite of all-cause mortality or recurrent MI obtained from national registries over a mean follow-up period of 3 years. Safety end points include rates of nonfatal MI, all-cause mortality, ventricular arrhythmias, and hospitalizations for heart failure obtained from hospital medical records 30 days after randomization, and from national registries after 6 and 18 months. Key secondary end points include recurrent MI, heart failure, cardiovascular and all-cause mortality, and clinical outcomes linked to β-blocker therapy including drug adherence, adverse effects, cardiovascular risk factors, psychosocial factors, and health economy. Statistical analyses will be conducted according to the intention-to-treat principle. A prespecified per-protocol analysis (patients truly on β-blockers or not) will also be conducted.

CONCLUSIONS

The results from the BETAMI trial may have the potential of changing current clinical practice for treatment with β-blockers following MI in patients without reduced LVEF. EudraCT number 2018-000590-75.

Treatment with Tacrolimus and Sirolimus Reveals No Additional Adverse Effects on Human Islets In Vitro Compared to Each Drug Alone but They Are Reduced by Adding Glucocorticoids

Tacrolimus and sirolimus are important immunosuppressive drugs used in human islet transplantation; however, they are linked to detrimental effects on islets and reduction of long-term graft function. Few studies investigate the direct effects of these drugs combined in parallel with single drug exposure. Human islets were treated with or without tacrolimus (30 μg/L), sirolimus (30 μg/L), or a combination thereof for 24 hrs. Islet function as well as apoptosis was assessed by glucose-stimulated insulin secretion (GSIS) and Cell Death ELISA. Proinflammatory cytokines were analysed by qRT-PCR and Bio-Plex. Islets exposed to the combination of sirolimus and tacrolimus were treated with or without methylprednisolone (1000 μg/L) and the expression of the proinflammatory cytokines was investigated. We found the following: (i) No additive reduction in function and viability in islets existed when tacrolimus and sirolimus were combined compared to the single drug. (ii) Increased expression of proinflammatory cytokines mRNA and protein levels in islets took place. (iii) Methylprednisolone significantly decreased the proinflammatory response in islets induced by the drug combination. Although human islets are prone to direct toxic effect of tacrolimus and sirolimus, we found no additive effects of the drug combination. Short-term exposure of glucocorticoids could effectively reduce the proinflammatory response in human islets induced by the combination of tacrolimus and sirolimus.

Drug target molecules to guide immunosuppression

The individual and interindividual variability of response to immunosuppressants combined with the prevailing concept of lifelong immunosuppression following any organ transplantation motivates the search for methods to further individualize such therapy. Traditional therapeutic drug monitoring, adapting dose according to concentrations in blood, targets the pharmacokinetic variability. It has been increasingly recognized, however, that there is also a considerable variability in the response to a given concentration. Attempts to overcome this variability in response include the efforts to identify relevant targets and methods for pharmacodynamic monitoring. For several of the currently used immunosuppressants there is experimental data suggesting markers that are relevant as indicators for individual monitoring of the effects of these drugs. There are also some clinical data to support these approaches; however what is generally missing, are studies that in a prospective manner demonstrates the benefits and effects on outcome. The monitoring of antithymocyte globulin by lymphocyte subset counts is actually the only well established example of pharmacodynamic monitoring. For drugs such as MPA and mTOR inhibitors, there are candidates such as IMPDH activity expression and p70SK6 phosphorylation status, respectively. The monitoring of CNIs using assays for NFAT RGE, either alone or combined with concentration measurements, is already well documented. Even here, some further investigations relating to the categories of organ transplant, combination of immunosuppressants etc. will be requested. Although some further standardization of the assay is warranted and there is a need for specific recommendations of target levels and how to adjust dose, the NFAT RGE approach to pharmacodynamic monitoring of CNIs may be close to implementation in clinical routine.

Clonidine in the treatment of adolescent chronic fatigue syndrome: a pilot study for the NorCAPITAL trial

BACKGROUND

This pilot study (ClinicalTrials.gov ID: NCT01507701) assessed the feasibility and safety of clonidine in adolescent chronic fatigue syndrome (CFS). Specifically, we assessed clonidine dosage in relation to a) plasma concentration levels, b) orthostatic cardiovascular responses, and c) possible adverse effects.

FINDINGS

Five adolescent CFS patients (14-19 years old) received 50 μg clonidine twice per day during 14 days in an open, uncontrolled design. Plasma concentration of clonidine was assayed by standard laboratory methods. Changes in orthostatic cardiovascular responses were assessed by a 20o head-up tilt-test (HUT). Adverse effects were mapped by a questionnaire.After 14 days, C0 median (range) of clonidine was 0.21 (0.18-0.36) μg/L, and Cmax median (range) of clonidine was 0.41 (0.38-0.56) μg/L. Also, supine blood pressures and heart rate were lower during clonidine treatment, and the HUT response was closer to the normal response. No serious adverse effects were registered.

CONCLUSION

Clonidine 50 μg BID seems to be safe enough to proceed from a pilot study to a controlled trial in a select group of adolescents with CFS (ClinicalTrials.gov ID: NCT01040429).

IMP dehydrogenase basal activity in MOLT-4 human leukaemia cells is altered by mycophenolic acid and 6-thioguanosine

OBJECTIVE

Depletion of guanine and deoxyguanine nucleotides by inhibition of inosine 5'-monophosphate dehydrogenase (IMPDH, EC 1.1.1.205) or introduction of 6-thioguanine nucleotide antimetabolites are two principles of retarding cell proliferation by interference with the cellular purine nucleotide pool. IMPDH activity may be a promising pharmacodynamic biomarker during immunosuppressive and anticancer pharmacotherapy. The aim of the study was to investigate the impact of mycophenolic acid (MPA) and 6-thioguanosine (tGuO) on IMPDH basal activity.

MATERIAL AND METHODS

We studied the IMPDH basal activity (i.e. the enzyme activity following inhibitor exposure, but measured in absence of the inhibitor) in response to increasing concentrations of the IMPDH inhibitor MPA and the antimetabolite tGuO in MOLT-4 human leukaemia cells. In parallel, IMPDH gene expression and cellular purine nucleotide concentrations were examined.

RESULTS

A biphasic concentration-dependent influence of MPA on the IMPDH basal activity was observed. At concentrations < or =IC50, MPA increased the IMPDH basal activity. The increase was associated with elevated expression of IMPDH2. Despite increased expression, the basal enzyme activity decreased following exposure to high MPA concentrations. The IMPDH2 expression increased modestly in response to tGuO exposure. However, the IMPDH basal activity decreased when the cells were exposed to a proliferation-blocking tGuO concentration.

CONCLUSIONS

These findings demonstrate that IMPDH basal activity is influenced by MPA and tGuO, and suggest that reduced IMPDH basal activity is related to the proliferation-blocking effects of these agents.

Cinacalcet's effect on the pharmacokinetics of tacrolimus, cyclosporine and mycophenolate in renal transplant recipients

BACKGROUND

The calcimimetic drug cinacalcet offers a novel therapeutic option to treat post-transplant hypercalcemia and hyperparathyroidism; however, the interaction with calcineurin inhibitors and mycophenolate has not been evaluated.

METHODS

In the present study the effects of cinacalcet on the pharmacokinetics of cyclosporine A (CsA), tacrolimus (Tac) and mycophenolate were investigated in 14 renal transplant recipients with stable renal function (mean creatinine 126.4 +/- 45.3 micromol/L). The patients were treated with either CsA (n = 8) or Tac (n = 6) in combination with mycophenolate/azathioprine and steroids. Twelve-hour pharmacokinetic investigations to measure CsA and its six main metabolites, Tac and mycophenolate concentrations were performed before and after 1-week treatment with 30 mg cinacalcet once daily.

RESULTS

Cinacalcet treatment induced a significant 14.3 +/- 12.1% decrease in Tac AUC(0-12) (P = 0.039). Tac C(max), T(max) and T(1/2) also tended to decrease. The pharmacokinetics of CsA and mycophenolate were not significantly affected by concomitant treatment with cinacalcet. However, the secondary CsA metabolite, AM19, showed a significant increase of 9.0 +/- 9.5% during cinacalcet treatment (P = 0.040). Renal function decreased significantly from 78 +/- 11 to 72 +/- 12 mL/min (P = 0.019) and correlated with the increased levels of metabolite AM19 in the CsA group. Renal function was unchanged in the Tac group.

CONCLUSION

Cinacalcet treatment showed a moderate effect on the Tac, but not CsA or mycophenolate, pharmacokinetics after 1-week concomitant treatment. This interaction appears to have minor clinical relevance. However, it is advisable to monitor renal function in CsA-treated patients due to the observed decrease in renal function.

Determination of inosine monophosphate dehydrogenase activity in human CD4+ cells isolated from whole blood during mycophenolic acid therapy

Inosine 5'-monophosphate dehydrogenase (IMPDH) is an established target in immunosuppression following organ transplantation. In lymphocytes, reversible inhibition of this enzyme by mycophenolic acid (MPA) results in reduced production of guanine and deoxyguanine nucleotides and thereby retarded proliferation of activated cells. In order to examine MPA pharmacodynamics in renal allograft recipients, the authors have developed an assay for the determination of IMPDH activity in CD4+ cells directly isolated from a small blood volume. Paramagnetic beads coated with anti-CD4 antibodies were utilized for the cell isolation. The intracellular MPA concentration was restored by incubating the cells in microfiltrated plasma from the original sample. Inosine 5'-monophosphate (IMP; substrate) and nicotine adenine dinucleotide (NAD; co-factor) were added to cell lysates, and IMPDH activity was quantified as the xanthosine 5'-monophosphate (XMP) production rate (pmol/10 cells/min) determined by liquid chromatography after hydrolytic cleavage to xanthine. The reaction kinetics were saturated with IMP and NAD concentrations of 1.79 micromol/L and 0.38 micromol/L, respectively. The production rate was linear in the interval 0.13 to 8.7 pmol XMP/min. Total interseries CVs based on seven replicates at each MPA concentration 0, 2.2, and 8.6 microg/mL were 25%, 16%, and 13%, respectively. When a single 1 gram mycophenolate mofetil dose was administered to a healthy individual, the measured IMPDH activity was 13% of predose value at the MPA peak concentration. The present assay allows reliable determination of IMPDH activity in CD4+ cells during MPA exposure, reducing the potential influence of sample preparation on the measured enzyme activity to a minimum. The assay may be applied to assess MPA pharmacodynamics during immunosuppressive treatment, maintaining the influence of intracellular MPA on the IMPDH activity.

Inosine monophosphate dehydrogenase activity in renal allograft recipients during mycophenolate treatment

OBJECTIVE

Mycophenolic acid (MPA) exerts its immunosuppression by inhibiting inosine 5'-monophosphate dehydrogenase (IMPDH), depleting activated lymphocytes of guanine nucleotides and retarding their proliferation. An optimal strategy for monitoring has not been established for mycophenolate mofetil (MMF) in renal transplantation, and clinical investigations of the pharmacokinetic-pharmacodynamic relationship are warranted.

MATERIAL AND METHODS

Mycophenolic acid pharmacokinetics and whole blood cell IMPDH activity were investigated in two separate groups of renal allograft recipients. One group was studied within the 12-h dose interval, while the second group was examined by pre-dose samples pre-transplant and then repeatedly during 8 weeks post-transplant.

RESULTS

An inverse relationship between plasma MPA and IMPDH activity within the dose interval was demonstrated. Minimum IMPDH activity was a median 8 % of values pre-MMF dose, coinciding with the MPA peak. Six hours post-dose, IMPDH activity had returned to pre-dose values. Patients receiving MMF had a 4.5-fold higher pre-dose enzyme activity than transplanted patients without MMF. During the 8 weeks post-transplant, the median MPA trough concentration was fairly stable. Following an initial decrease during the first 4 days post-transplant, IMPDH activity gradually increased during the 40 days post-transplant, reaching 5-fold the pre-transplant values.

CONCLUSIONS

Provided that the changes in IMPDH activity in whole blood cells predict the clinical effect, these pharmacokinetic-pharmacodynamic findings may prove useful in the attempts to identify optimal timing and range for the monitoring of mycophenolate in renal transplantation. The question of whether MPA concentrations or measurements of IMPDH activity per se will be the optimal way of monitoring this immunosuppressant remains open and will only be answered by prospective clinical testing.