Therapy of hyperlipidemia with lovastatin in kidney transplant patients on cyclosporine A immunosuppression: three-year experience

Incidence, predictors and associated outcomes of rhabdomyolysis after kidney transplantation

BACKGROUND

There are several case reports of rhabdomyolysis (RM) in renal transplant recipients, but the actual incidence of this complication is not known. Most of the reported cases have been attributed to drug-drug interactions with calcineurin inhibitors, with the majority of interactions reported between cyclosporine and 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins). Pharmacokinetic studies have demonstrated that cyclosporine increases statin drug levels, presumably via competitive inhibition of cytochrome P450 3A4.

METHODS

In a retrospective cohort of 20 366 adult Medicare primary renal transplant recipients in the USRDS database transplanted from 1 January 2003 to 31 July 2005 and followed through 31 December 2005, we assessed Medicare claims for RM and dyslipidaemia (HPL), which was used as a surrogate for statin use.

RESULTS

The incidence rate of RM post-transplant for the study period was 1.4 (95% CI 1.1-1.8) per 1000 person-years. By Cox regression analysis, cyclosporine (versus tacrolimus) use [AHR 2.36 (95% CI 1.23-4.35); P = 0.006] and black race [AHR 2.33 (95% CI 1.30-4.17); P = 0.005] were associated with RM. By Cox non-proportional hazards regression, RM was associated with graft loss (including death) [AHR 2.84 (95% CI 1.70-4.72); P < 0.001].

CONCLUSIONS

RM is a rare complication after renal transplantation and is significantly associated with allograft loss (including death). RM is significantly more likely to occur with cyclosporine (versus tacrolimus)-based immunosuppression and possibly in persons of black race. Increased surveillance for RM is warranted in these at-risk patients.

Drug Therapy in Transplant Recipients

Elderly patients with end-stage organ failure are now more frequently undergoing transplantation. Medication management in this population is challenging because of the combination of multiple comorbidities, polypharmacy, and immunological, pharmacokinetic and pharmacodynamic changes attributable to the aging process. Immunosuppressive medications can exacerbate pre-existing medical conditions and promote the development of disease processes. Cardiovascular disorders, such as hypertension, coronary artery disease, congestive heart failure and arrhythmias are common in elderly transplant recipients, and account for most of the deaths in this population. Blood pressure, blood glucose and cholesterol control is of particular concern because elderly transplant recipients frequently have or develop these complications. Elderly transplant recipients are commonly receiving anticoagulation therapy with warfarin and are at a higher risk of bleeding, especially if they have renal dysfunction. Infectious complications occur frequently in the transplanted population, with pneumonia being the most common infection seen in hospitalised patients. Attention to vaccination for the prevention of influenza and pneumococcal infections is important because of the increased risk of these diseases in this population. Depression itself has been associated with decreased survival in older individuals, and depression in elderly transplant recipients may be reversible with the administration of pharmacological agents. Effective long-term care of transplant recipients demands an understanding of how particular medications affect clinical evaluation and treatment. This article addresses some of the practical issues surrounding medication management and prevention of these particular problems in elderly transplant recipients.

Management of selected lipid abnormalities: hypertriglyceridemia, isolated low HDL-cholesterol, lipoprotein(a), and lipid abnormalities in renal diseases and following solid organ transplantation

Although the focus in treating lipid disorders is on reducing LDL-C levels, additional lipid-related independent risk factors, such as TG, HDL-C, and Lp(a) levels, should be used clinically to assess cardiovascular risk. Decisions to initiate drug therapy for LDL-C reduction may be influenced by levels of these other lipoprotein fractions. Data supporting intervention to modify these factors are less abundant than for LDL-C reduction, but in certain circumstances. drug therapy targeted at TGs or HDL-C may be appropriate. Patients who have nephrotic syndrome and end-stage renal disease are at particularly high risk for the development of CVD and should be treated aggressively for their lipid disorders. Finally, solid organ transplant recipients are almost always hyperlipidemic and appropriate therapy could reduce cardiovascular events.

[Pharmacological interactions of statins]

OBJECTIVE

To determine in primary care the frequency of pharmacological interactions of statins.

DESIGN

Transversal observational study.Setting. Urban health centre.Participants. 384 patients taking statins who were chosen by systematic sampling based on long-treatment cards (95% CI, accuracy 5% and expected proportion of possible interactions unknown).

MAIN MEASUREMENTS

Consumption of statins, the accompanying medication taken, presence of interactions according to the technical details of statins (Spanish Medication Agency, Ministry of Health and Consumption) and social and demographic variables.

RESULTS

In 55 patients (14.3%) (95% CI, 10.8%-17.8%) one of the statin interactions with the other drugs was checked, especially with acenocoumarol, digoxin and anti-acid drugs. In patients with some interaction, the mean number of other drugs was significantly higher (4.51.5 vs 3.31.9 SD; P<.001). 19.1% of men and 10.8% of women showed interactions, the difference being statistically significant (P=.02). By means of logistic regression, both masculine gender (OR=1.8) and taking of other medication in quantities of 5 or more (OR=2.7) appeared as variables associated with the presence of interactions.

CONCLUSIONS

The potential pharmacological interactions of statins reach 14.3% of patients with hypercholesterolaemia who take medication long-term. The possibility of reaching high plasma concentrations of statins and/or of modifying the therapeutic effect of various drugs enables a more appropriate use of statins to be recommended, with prescription of those statins that metabolise less through the P450 cytochrome.

Calcineurin inhibitors and post-transplant hyperlipidaemias

Cardiovascular disease is now the leading cause of death in transplant recipients. This is due, in part, to the vulnerability of these patients to a complicated set of conditions including hypertension, diabetes mellitus, and post-transplant hyperlipidaemia (PTHL). PTHL is characterised by persistent elevations in total serum cholesterol, low density lipoprotein cholesterol and triglyceride levels. The causes of PTHL are complex and not fully understood, however several classes of immunosuppressants including the corticosteroids, rapamycins and calcineurin inhibitors, appear to play a role. PTHL has been observed in most studies in which patients received calcineurin inhibitor-based regimens, and has been observed with both tacrolimus and cyclosporin. Comparing these calcineurin inhibitors with regard to the relative incidence or severity of PTHL occurring during treatment is difficult because of the use of higher doses of corticosteroids in cyclosporin-based regimens, as compared with tacrolimus-based regimens. However, current expert opinion suggests that the discrepancies in the relative incidence and severity of PTHL are largely accounted for by this difference in corticosteroid dose. At this point in time, evidence for potential differences is scant and inconclusive. Further study is needed, not only to investigate differences in lipid profile, but also of the relative effects of these immunosuppressants on long term graft function as well as on cardiovascular morbidity and mortality. PTHL can be successfully managed with a combination of dietary management, reduction and, if appropriate, withdrawal of corticosteroids, and the administration of lipid-lowering drugs. With this combination of therapeutic options, the threats to long term health posed by PTHL may be effectively addressed.

Pharmacokinetics and pharmacodynamics of fluvastatin in heart transplant recipients taking cyclosporine A

During the last decades, transplantation has become an established tool for the treatment of terminal organ failure. Beside immunological factors, hyperlipidemia is the main problem after heart transplantation, causing rapid transplant coronary artery disease (TxCAD) and poor long-term prognosis at the beginning of the transplantation. Heart transplant recipients are now effectively treated with lipid lowering substances, of which HMG-CoA-reductase inhibitors are the most potent. However, treatment with these substances correlates with an increased risk for the development of rhabdomyolysis due to therapy with the immunosuppressive cyclosporine A. Our study monitored the safety and efficacy of treatment with the HMG-CoA reductase inhibitor fluvastatin in heart transplant recipients compared to healthy controls. We investigated 10 patients receiving immunosuppressive therapy consisting of cyclosporine A, prednisone, and azathioprine who had increased concentrations of LDL-cholesterol (LDL-C), and 10 age-matched healthy controls. The patients were treated with 40 mg/day fluvastatin for 4 weeks and 20 mg/day for 4 additional weeks. Control individuals received 40 mg/day fluvastatin for 4 weeks only. Parameters of fluvastatin pharmacokinetics (maximum concentration of the drug (C(max.)), time (t(max.)) to reach C(max.), area under the concentration vs. time curve (AUC(0h-24h)), elimination half-life time (t(1/2))), apparent total body clearance (CL), blood cyclosporine A concentration, plasma lipids, and safety parameters were determined in both study groups at the beginning of the study and after 4 weeks. The latter were determined in the patient group also after 8 and 12 weeks. Treatment with 40 mg/day fluvastatin caused a significant decrease in total cholesterol (patients: 5.47 +/- 1.32 mmol/L vs. 7.30 +/- 1.83 mmol/L; controls: 4.69 +/- 0.64 mmol/L vs. 5.81 +/- 0.72 mmol/L), LDL-C (patients: 3.28 +/- 1.25 mmol/L vs. 5.00 +/- 1.85 mmol/L; controls: 2.58 +/- 0.63 mmol/L vs. 3.50 +/- 0.70 mmol/L), and triglycerides (patients: 1.99 +/- 0.77 mmol/L vs. 2.50 +/- 1.00 mmol/L; controls: 1.24 +/- 0.46 mmol/L vs. 1.72 +/- 0.67 mmol/L) in both study groups, whereas HDL-C was not significantly changed (patients: 1.29 +/- 0.35 mmol/L vs. 1.17 +/- 0.32 mmol/L; controls: 1.55 +/- 0.30 mmol/L vs. 1.53 +/- 0.26 mmol/L). Values of C(max.) and AUC(0h-24h) were higher in the patient group than in the control group (day 1, patients vs. controls, C(max.): 869.4 +/- 604.0 ng/mL vs. 211.9 +/- 113.9 ng/mL; AUC(0h-24h): 1948.8 +/- 1347.9 ng/mL*h vs. 549.4 +/- 247.4 ng/mL*h), whereas the corresponding value of CL was lower in the patient group (33.3 +/- 24.5 L/h vs. 107.9 +/- 95.8 L/h), and the values of t(max.) and t(1/2) showed no differences. In addition, values of C(max.) and AUC(0h-24h) after administration of 40 mg/day fluvastatin for 4 weeks in both groups were slightly higher than at the beginning, whereas the value of CL was slightly lower (day 28, patients vs. controls, C(max.): 1530.4 +/- 960.4 ng/mL vs. 254.7 +/- 199.8 ng/mL; AUC(0h-24h): 2615.3 +/- 1379.4 ng/mL*h vs. 841.8 +/- 421.4 ng/mL*h; CL: day 28, 21.4 +/- 15.3 L/h vs. 61.5 +/- 36.6 L/h). Except for an intermittent increase of creatine kinase, safety parameters showed no increases within the observation period. Our data suggest that fluvastatin effectively lowers plasma concentrations of cholesterol and LDL-C in patients after heart transplantation, however, the metabolism of fluvastatin is affected by concomitant therapy with cyclosporine A. Serum concentrations of fluvastatin should be monitored in cases of concomitant therapy with other substances interfering in the metabolism by competing cytochrome enzymes.

Management of selected lipid abnormalities. Hypertriglyceridemia, low HDL cholesterol, lipoprotein(a), in thyroid and renal diseases, and post-transplantation

Although the focus in treating lipid disorders is on reducing LDL cholesterol levels, triglycerides, HDL cholesterol, and Lp(a) are all independent risk factors that can be used clinically to assess cardiovascular risk. Decisions to initiate drug therapy for LDL cholesterol reduction may be influenced by levels of these other lipoprotein fractions. Data supporting intervention to modify these factors is less abundant than for LDL cholesterol reduction, but in certain circumstances drug therapy targeted at triglycerides or HDL cholesterol may be appropriate. Patients with nephrotic syndrome and end-stage renal disease are at particularly high risk for the development of cardiovascular disease and should be treated aggressively for lipid disorders. Finally, solid organ transplant recipients are almost always hyperlipidemic, and appropriate therapy could reduce cardiovascular events.

New insights into the pharmacodynamic and pharmacokinetic properties of statins

The beneficial effects of statins are assumed to result from their ability to reduce cholesterol biosynthesis. However, because mevalonic acid is the precursor not only of cholesterol, but also of many nonsteroidal isoprenoid compounds, inhibition of 3-hydroxy-3-methylglutaryl coenzyme A reductase may result in pleiotropic effects. It has been shown that several statins decrease smooth muscle cell migration and proliferation and that sera from fluvastatin-treated patients interfere with its proliferation. Cholesterol accumulation in macrophages can be inhibited by different statins, while both fluvastatin and simvastatin inhibit secretion of metalloproteinases by human monocyte-derived macrophages. The antiatherosclerotic effects of statins may be achieved by modifying hypercholesterolemia and the arterial wall environment as well. Although statins rarely have severe adverse effects, interactions with other drugs deserve attention. Simvastatin, lovastatin, cerivastatin, and atorvastatin are biotransformed in the liver primarily by cytochrome P450-3A4, and are susceptible to drug interactions when co-administered with potential inhibitors of this enzyme. Indeed, pharmacokinetic interactions (e.g., increased bioavailability), myositis, and rhabdomyolysis have been reported following concurrent use of simvastatin or lovastatin and cyclosporine A, mibefradil, or nefazodone. In contrast, fluvastatin (mainly metabolized by cytochrome P450-2C9) and pravastatin (eliminated by other metabolic routes) are less subject to this interaction. Nevertheless, a 5- to 23-fold increase in pravastatin bioavailability has been reported in the presence of cyclosporine A. In summary, statins may have direct effects on the arterial wall, which may contribute to their antiatherosclerotic actions. Furthermore, some statins may have lower adverse drug interaction potential than others, which is an important determinant of safety during long-term therapy.