Rhabdomyolysis after concomitant use of cyclosporine, simvastatin, gemfibrozil, and itraconazole

Simultaneous administration of fluoxetine and simvastatin ameliorates lipid profile, improves brain level of neurotransmitters, and increases bioavailability of simvastatin

Simvastatin (STT), a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, is widely prescribed for dyslipidemia, whereas fluoxetine (FLX) is the first-choice drug for the treatment of depression and anxiety. A recent report suggests that selective serotonin reuptake inhibitors can interact with the cytochrome P450 3A4 substrate, and another one suggests that STT enhances the antidepressant activity of FLX. However, the data are inconclusive. The present study was designed to explore the pharmacokinetic and pharmacodynamic consequences of coadministration of STT and FLX in experimental animals. For this, Wistar rats weighing 250±10 g were divided into four groups, including control, STT (40 mg/kg/day), FLX (20 mg/kg/day), and STT+FLX group, respectively. After the dosing period of 4 weeks, the animals were sacrificed, and the blood and brain samples were collected for the analysis of STT, simvastatin acid (STA), FLX, total cholesterol, triglyceride, high-density lipoprotein (HDL), 5-hydroxytryptamine, dopamine, and hydroxy indole acetic acid. It was found that the coadministration resulted in a significant increase in the bioavailability of STT in the plasma (41.8%) and brain (68.7%) compared to administration of STT alone (p<0.05). The maximum drug concentration (C_max) of STT was also found to be increased significantly in the plasma and brain compared to that achieved after monotherapy (p<0.05). However, STT failed to improve the pharmacokinetics of FLX up to a significant level. The results of this study showed that the combined regimen significantly reduced the level of cholesterol and triglyceride and increased the level of HDL when compared to STT monotherapy. Furthermore, the coadministration of STT with FLX led to an elevated level of neurotransmitters in the brain (p<0.05). FLX increased the concentration of STT in the plasma and brain. The coadministration of these drugs also led to an improved lipid profile. However, in the long-term, this interaction may have a vital clinical importance because the increase in STT level may lead to life-threatening side effects associated with statins.

Feasibility of Prioritizing Drug-Drug-Event Associations Found in Electronic Health Records

Background and Objective

Several studies have demonstrated the ability to detect adverse events potentially related to multiple drug exposure via data mining. However, the number of putative associations produced by such computational approaches is typically large, making experimental validation difficult. We theorized that those potential associations for which there is evidence from multiple complementary sources are more likely to be true, and explored this idea using a published database of drug–drug-adverse event associations derived from electronic health records (EHRs).

Methods

We prioritized drug–drug-event associations derived from EHRs using four sources of information: (1) public databases, (2) sources of spontaneous reports, (3) literature, and (4) non-EHR drug–drug interaction (DDI) prediction methods. After pre-filtering the associations by removing those found in public databases, we devised a ranking for associations based on the support from the remaining sources, and evaluated the results of this rank-based prioritization.

Results

We collected information for 5983 putative EHR-derived drug–drug-event associations involving 345 drugs and ten adverse events from four data sources and four prediction methods. Only seven drug–drug-event associations (<0.5 %) had support from the majority of evidence sources, and about one third (1777) had support from at least one of the evidence sources.

Conclusions

Our proof-of-concept method for scoring putative drug–drug-event associations from EHRs offers a systematic and reproducible way of prioritizing associations for further study. Our findings also quantify the agreement (or lack thereof) among complementary sources of evidence for drug–drug-event associations and highlight the challenges of developing a robust approach for prioritizing signals of these associations.

Electronic supplementary material

The online version of this article (doi:10.1007/s40264-015-0352-2) contains supplementary material, which is available to authorized users.

Statin-associated rhabdomyolysis triggered by drug-drug interaction with itraconazole

A 47-year-old woman had been treated with high-dose simvastatin for several years. After systemic treatment with the antifungal agent itraconazole, she developed muscle pain and highly elevated levels of creatine kinase and myoglobin. Muscle biopsy was compatible with statin-associated rhabdomyolysis, probably caused by a drug-drug interaction between simvastatin and itraconazole. The patient made full recovery. Three commonly used statins-simvastatin, atorvastatin and lovastatin-are metabolised by the liver enzyme CYP3A4. Several potent inhibitors of this enzyme are known, for example, azole antifungal agents such as itraconazole and posaconazole. If antifungal treatment is indicated in a patient using a CYP3A4-metabolised statin, we recommend (1) topical administration of the antifungal agent if possible, (2) the use of a non-CYP3A4-inhibiting antifungal drug such as terbinafine or (3) temporary discontinuation of statin treatment.

Pharmacokinetic model for the inhibition of simvastatin metabolism by itraconazole

BACKGROUND

Concomitant use of simvastatin, a HMG-CoA reductase inhibitor, with a potent CYP3A4 inhibitor, itraconazole, can result in a serious drug-drug interaction induced severe adverse event, rhabdomyolysis. Even though pharmacokinetic data regarding such interaction are available, they cannot be used for quantitative prediction. For this reason, we aimed to develop a pharmacokinetic model for predicting the magnitude of inhibition of simvastatin metabolism by itraconazole.

METHODS

Published data involving pharmacokinetic of simvastatin, itraconazole, and pharmacokinetic interaction between simvastatin and itraconazole were selected from PubMed search. Serum simvastatin concentrations were subsequently extracted and used for model development. Advanced Continuous Simulating Language Extreme (ACSLX) was used for modeling.

RESULTS

The drug-drug interaction model between simvastatin and itraconazole was simultaneously modeled using a one compartment parent-metabolite model for simvastatin, and a two-compartment model for itraconazole.

CONCLUSION

The final drug-drug interaction model can adequately describe the actual simvastatin concentrations. Model application can be of advantage for dosing adjustment to avoid serious adverse effects resulted from concomitant use of both drugs.

Rhabdomyolysis as a clinical manifestation of association with ciprofibrate, sirolimus, cyclosporine, and pegylated interferon-α in liver-transplanted patients: a case report and literature review

BACKGROUND

Rhabdomyolysis is a syndrome characterized by impaired metabolic integrity of myocytes, causing the release of intracellular constituents into the circulation, and can be a serious side effect of drug intake.

CASE REPORT

This report describes a unique case of rabdomyolysis secondary in which ciprofibrate, sirolimus, cyclosporine, and pegylated interferon-α in a liver transplant patient was used. A 47-year-old male liver transplant recipient in 2009, who had hepatitis C and incidental hepatocellular carcinoma, underwent immunosuppressive therapy (cyclosporine and sirolimus). The patient is currently in treatment for viral recurrence with pegylated interferon-α and ribavirin; he had a history of hypertriglyceridemia treated with ciprofibrate. He had development of severe and generalized myalgia and fever after the eighth application of pegylated interferon-α and increasing doses of cyclosporine. Laboratorial tests showed acute renal failure and significant increase in creatine kinase. Rhabdomyolysis secondary to interaction of fibrate-cyclosporine-pegylated interferon-α was postulated.

CONCLUSIONS

Medical professionals should be aware of possible drug interactions and should monitor patients receiving these drugs.

Adverse effects of low-dose systemic cyclosporine therapy in high-risk penetrating keratoplasty

PURPOSE

The purpose of this study was to investigate the adverse effects of low-dose oral cyclosporine (CsA) therapy following high-risk corneal transplantation.

METHODS

The medical records from 88 subjects who had undergone high-risk penetrating keratoplasties and had been administered oral CsA were retrospectively analyzed. High risk was defined as a history of graft rejection, three or more quadrants of vascularization, or the presence or history of intraocular inflammation. An initial CsA dose of 3-5 mg/kg per day was given for 3-7 days, followed by 2.5-3.5 mg/kg per day for approximately 1 month. The concentration of CsA was maintained at the target trough level of 120-150 ng/ml for at least 6 months or until serious complications developed. The relationship between the cumulative dose and duration of CsA administration and the adverse systemic effects, including the frequency of herpes keratitis, was evaluated. The incidence of herpes keratitis in the study subjects was compared with the incidence in 185 patients who had not received CsA therapy following penetrating keratoplasty.

RESULTS

The mean survival time of the grafts was 33.6 months. Adverse effects occurred in 81.8 % of subjects. Hypertension, elevated liver enzyme levels, elevated serum creatinine level, and decreased absolute neutrophil count (ANC) were observed in 14.8, 6.8, 5.7, and 5.7 % of subjects, respectively. Simvastatin-induced rhabdomyolysis also developed in one case. Some patients exhibited minor complications, with gastrointestinal problems and hypertrichosis recorded in 5.7 and 3.4 % of subjects, respectively. Hypertension and hepatotoxicity most frequently occurred after 4 to 8 weeks of medication, while ANC decrease and nephrotoxicity generally developed after 24 weeks of treatment, with incidence related to the cumulative dose. Herpes keratitis occurred more frequently (31.8 %) in the CsA-treated subjects than in subjects that did not receive CsA therapy (p = 0.005). Most of the adverse effects were reversed after discontinuation of CsA therapy.

CONCLUSION

The results of this study suggest that low-dose oral CsA therapy may induce various adverse effects, the most common of which are herpes keratitis and hypertension.

Effect of vitamin D on bioavailability and lipid lowering efficacy of simvastatin

The 3-hydroxy 3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) inhibitors known as "statins" are widely prescribed for the management of dyslipidemia. In spite of their muscle toxicity, use of statins has alarmingly increased worldwide. A recent report suggests that vitamin D (VD) levels are closely associated with lipid lowering activity and muscular toxicity of statins. However, data are limited and inconclusive. The present study was undertaken to investigate the effect of VD supplementation on the bioavailability and lipid lowering effect of simvastatin (ST). Adult Sprague-Dawley male rats (250 ± 10 g) were divided into four groups including control, ST (100 mg/kg/day), VD (100 μg/kg/day) and ST + VD group, respectively. After the dosing period of 8 days the animals were sacrificed and the blood was collected for the analysis of ST, its active metabolite simvastatin acid (STA), total cholesterol, triglyceride and liver enzymes including aspartate transaminase and alanine transaminase. The result of this study showed a significant decrease in the level of cholesterol and triglyceride in ST alone treated group, whereas VD alone failed to alter the blood lipid levels. Concomitant treatment with VD produced significant decrease in the bioavailability of ST and STA. However, there was no significant difference in the level of cholesterol in ST alone and in ST + VD treated group. Our results on the liver enzyme suggest that ST alone or in combination with VD does not produce any hepatotoxicity. Further studies using VD along with various statins for a longer duration are suggested.

[Maximal initial dose of simvastatin causing acute renal failure through rhabdomyolysis: risk factors, pathomechanism and therapy related to a case]

Rhabdomyolysis (RML) is a rare and severe adverse effect of simvastatin (SIM). Several risk factors have been described which play a role in its pathogenesis, namely age >65, diabetes mellitus, renal disease, high-dose statin therapy, chemicals metabolized by cytochrome P450 3A4 or idiosyncrasy.

CASE SUMMARY

A 66-year-old man with diabetes, ischaemic heart disease and hypertension, on medication of CYP3A4 substrates amlodipine and alprazolam, maximal daily dose of SIM has been started for unknown cholesterol level. On the second day dark-brown urine, paraparesis, bile-like vomiting, on his fourth day of treatment total tetraparesis and oliguria characterized RML with acute renal failure. During his hospitalization of one-hundred-six days he underwent fourty-nine dialysis treatments. Sixteen months follow-up after discharge from hospital, his walking improved up to using one stick now. His cholesterol level is in physiological range with no statin therapy.

CONCLUSIONS

On account of risk factors listed above this case should have been administered to low initial dose of SIM. Developing myalgia or weakness in muscles, treatment must be stopped. In a case of predisposition to RML statin therapy and dosage can only be performed under continuous supervision.

A Comparison of Adverse Effects of Simvastatin plus Gemfibrozil and Atorvastatin plus Gemfibrozil

Background

The manufacturer of simvastatin recommends a dose limitation of 10 mg daily when used in combination with gemfibrozil, due to increased risk of myopathy and rhabdomyolysis. Little information is available regarding the risk of adverse effects of atorvastatin when used in combination with gemfibrozil.

Purpose

To compare the rate of discontinuation or dose reduction due to adverse effects with simvastatin and gemfibrozil versus atorvastatin and gemfibrozil.

Methods

Retrospective review of patients taking gemfibrozil in combination with simvastatin 10 mg, simvastatin 80 mg, or atorvastatin 40 mg for at least 6 months.

Results

A total of 166 patients were included; 59 were taking simvastatin 10 mg (S10), 47 were taking simvastatin 80 mg (S80), and 60 were taking atorvastatin 40 mg (A40). There was no significant difference in the rate of discontinuation or dose reduction due to adverse effects among the groups (10.2% for S10, 21.2% for S80, and 10% for A40, P = 0.159). A paired comparison of discontinuation or dose reduction due to adverse effects between the simvastatin 80 mg and atorvastatin 40 mg groups approached a trend toward a difference ( P = 0.104). Severe adverse effects occurred in the simvastatin 80 mg and atorvastatin 40 mg groups.

Conclusion

Our results did not show a significant difference in discontinuation or dose reduction due to adverse effects between patient groups taking gemfibrozil in combination with simvastatin 10 mg, simvastatin 80 mg, or atorvastatin 40 mg. However, the rate of this outcome in the S80 group was approximately double that for the S10 and A40 groups. Further studies are needed to compare the safety of these statin-gemfibrozil combinations.

What Do Medical Records Tell Us About Potentially Harmful Co-Prescribing?

BACKGROUND

Previous efforts document drug-drug interactions in ambulatory care. Yet little is known about medical record documentation or clinical management when interacting medications are received.

METHODS

The study population was identified from the HMO Research Network's Centers for Education and Research on Therapeutics (n = 2,020,037). A random subsample of patients > or = 18 years of age with drug coverage in 2000 initiating a co-dispensing for (1) warfarin with a nonsteroidal anti-inflammatory drug (n = 97), (2) digoxin with verapamil or diltiazem (n = 100), or (3) lovastatin/simvastatin with diltiazem or verapamil (n = 89) was identified.

RESULTS

The majority (63%-74%) of patients had documentation indicating receipt of both drugs during a single office visit. Documentation of risks and patient education was less common (< or = 14%, with all corresponding upper bounds of the 95% CIs < 23%). Clinical management changes were more frequently documented, ranging from 64% (95% CI: 47-81%) for lovastatin/simvastatin patients to 79% (95% CI: 60-99%) for warfarin patients.

CONCLUSIONS

The findings, although indicating that clinicians are likely aware of concomitant receipt of interacting medications, call into question the adequacy of medical record documentation as well as clinical management when interacting drugs are co-prescribed in the ambulatory setting.

Intravenous and oral sequential itraconazole antifungal prophylaxis in paediatric stem cell transplantation recipients: a pilot study for evaluation of safety and efficacy

This single-centre, retrospective, observational pilot study was performed to evaluate the safety and efficacy of intravenous and oral itraconazole prophylaxis in paediatric haematopoietic stem cell transplantation (HCT). Study end-points were proven invasive fungal infection (IFI), survival, adverse reactions and graft-vs.-host disease (GVHD); 53 children and one young adult (median age 8.6 yr; range 0.4-18.3) transplanted between November 2001 and August 2004 were included in this study. Itraconazole was given intravenously from day +3 after HCT until oral medication became possible and continued until day +100 after HCT. Two proven new IFI in the itraconazole group (candidiasis, n = 1; aspergillosis, n = 1) were observed. After a median follow-up of 1.6 yr (0.3-6.1), six deaths (8%) were seen; 24 patients (45%) developed GVHD degree I-II, three children (6%) had GVHD degree III-IV. In 11 of 53 patients (21%), itraconazole prophylaxis was discontinued prematurely, mostly because of fever of unknown origin (n = 7). In total, 21 of 53 (40%) of the children had abnormal results of laboratory investigations during the prophylaxis. The results of this pilot study indicate that itraconazole prophylaxis during HCT in children is feasible and safe, despite abnormal laboratory results. The efficacy in terms of prevention of IFI, however, has to be addressed in a prospective large-scale study.

Lipid Lowering Inefficacy of High-dose Statin Therapy Due to Concurrent Use of Phenytoin

HMG-CoA reductase inhibitors ("statins") are the most commonly prescribed lipid lowering agents. Most of the statins are metabolized by the CYP450 cytochrome system. A number of medications either induce or inhibit this system which leads to changes in the bioavailability of the statins and the potential for either an increase in adverse effects or reduction in efficacy. Phenytoin induces the CYP3A4 isoform of the CYP450 system and can reduce the bioavailability, and thus the efficacy of the statins metabolized by this enzyme, including atorvastatin and lovastatin. A case of a patient on multiple lipid-lowering medications, including high-dose atorvastatin whose LDL cholesterol improved significantly after discontinuation of phenytoin is presented, and a review of the literature for similar cases is discussed.

Treating dyslipidaemia in the setting of diabetes mellitus and cardiovascular disease: a less commonly perceived therapeutic perspective in clinical practice

Diabetes mellitus and cardiovascular disease are being managed more belligerently in recent times, with multifactorial cardiovascular risk reduction being the focus of therapeutic interventions. We review some of the caveats to be exercised in the treatment of these patients that are pertinent to clinicians in daily clinical practice.

Potential Drug–Drug Interactions in the Outpatient Setting

BACKGROUND

Although medication safety research has tended to focus on inpatients, the safety of drug use among outpatients is also a concern.

OBJECTIVE

We estimate the frequency of potentially interacting concomitant medication dispensing among outpatients.

RESEARCH DESIGN

We report the number and percent of patients annually dispensed an object drug of interest (ie, warfarin, digoxin, cyclosporine, or lovastatin/simvastatin) with a potentially interacting drug among a random sample of insured adults receiving care from 10 integrated delivery systems. We use 2 definitions of concomitant dispensing: medications dispensed: 1) during the time period for which the patient had the other medication available ('days supply') and 2) on the same day. We also estimate the number of insured U.S. population codispensed these medication pairs.

RESULTS

Among patients dispensed a drug of interest, between 17.8% (95% confidence interval [CI]=17.1-18.6%) and 28.0% (95% CI=24.0-32.1%) were concomitantly dispensed a potentially interacting drug using the "days supply" definition, and between 7.1% (95% CI=6.6-7.7%) and 17.7% (95% CI=14.4-21.1%) using the "same day" definition. Extrapolating to the insured U.S. population, between 1.29 (95% CI=1.25-1.33; same day) and 2.67 (95% CI=2.62-2.72; days supply) million insured adults are dispensed 1 of these 4 potentially interacting pairs.

CONCLUSIONS

We found evidence of potentially interacting concomitant medication dispensing among outpatients. An opportunity exists to better understand how such dispensing translates into adverse events and ultimately to improved medication safety.

Clinical perspectives of statin-induced rhabdomyolysis

Fear of muscle toxicity remains a major reason that patients with hyperlipidemia are undertreated. Recent evaluations of statin-induced rhabdomyolysis offer new insights on the clinical management of both muscle symptoms and hyperlipidemia after rhabdomyolysis. The incidence of statin-induced rhabdomyolysis is higher in practice than in controlled trials in which high-risk subjects are excluded. Accepted risks include age; renal, hepatic, and thyroid dysfunction; and hypertriglyceridemia. New findings suggest that exercise, Asian race, and perioperative status also may increase the risk of statin muscle toxicity. The proposed causes and the relationship of drug levels to statin rhabdomyolysis are briefly reviewed along with the problems with the pharmacokinetic theory. Data suggesting that patients with certain metabolic abnormalities are predisposed to statin rhabdomyolysis are presented. The evaluation and treatment of patients' muscle symptoms and hyperlipidemia after statin rhabdomyolysis are presented. Patients whose symptoms are related to other disorders need to be identified. Lipid management of those whose symptoms are statin-related is reviewed including treatment suggestions.

Pharmacokinetic Evaluation of the Drug Interaction between Intravenous Itraconazole and Intravenous Tacrolimus or Intravenous Cyclosporin A in Allogeneic Hematopoietic Stem Cell Transplant Recipients

A single-institution, open-label prospective pharmacokinetic evaluation of the interaction between intravenous itraconazole and intravenous cyclosporin A and tacrolimus was conducted in allogeneic hematopoietic stem cell transplant recipients. The study was conducted in 2 phases, with patients acting as their own controls. In phase 1, steady-state concentrations and clearance of cyclosporin A and tacrolimus administered alone were evaluated. Phase 2 evaluated serum concentrations and clearance of cyclosporin A and tacrolimus under the influence of itraconazole therapy. Among 17 patients who completed both phases of the study, the mean increase in the serum tacrolimus concentration was 83% (P<.0001), and the mean increase in the serum cyclosporin A concentration was 80% (P=.0001). There was no correlation between serum itraconazole concentrations and the serum concentrations of tacrolimus or cyclosporin A. The drug interaction between itraconazole and calcineurin inhibitors is predictable and occurs within 48 hours of concomitant drug administration. The data suggest that dose reductions of tacrolimus and cyclosporin A in the range of 50% to 100% are necessary when itraconazole therapy is initiated and that subsequent close monitoring of serum concentrations is necessary to guide further dose modifications.

Frequency of potential azole drug-drug interactions and consequences of potential fluconazole drug interactions

PURPOSE

To assess the frequency of potential azole-drug interactions and consequences of interactions between fluconazole and other drugs in routine inpatient care.

METHODS

We performed a retrospective cohort study of hospitalized patients treated for systemic fungal infections with an oral or intravenous azole medication between July 1997 and June 2001 in a tertiary care hospital. We recorded the concomitant use of medications known to interact with azole antifungals and measured the frequency of potential azole drug interactions, which we considered to be present when both drugs were given together. We then performed a chart review on a random sample of admissions in which patients were exposed to a potential moderate or major drug interaction with fluconazole. The list of azole-interacting medications and the severity of interaction were derived from the DRUGDEX System and Drug Interaction Facts.

RESULTS

Among the 4,185 admissions in which azole agents (fluconazole, itraconazole or ketoconazole) were given, 2,941 (70.3%) admissions experienced potential azole-drug interactions, which included 2,716 (92.3%) admissions experiencing potential fluconazole interactions. The most frequent interactions with potential moderate to major severity were co-administration of fluconazole with prednisone (25.3%), midazolam (17.5%), warfarin (14.7%), methylprednisolone (14.1%), cyclosporine (10.7%) and nifedipine (10.1%). Charts were reviewed for 199 admissions in which patients were exposed to potential fluconazole drug interactions. While four adverse drug events (ADEs) caused by fluconazole were found, none was felt to be caused by a drug-drug interaction (DDI), although in one instance fluconazole may have contributed.

CONCLUSIONS

Potential fluconazole drug interactions were very frequent among hospitalized patients on systemic azole antifungal therapy, but they had few apparent clinical consequences.

Analysis of the global RNA expression profiles of skeletal muscle cells treated with statins

The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) are the most effective drugs for hypercholesteloremia. However, a significant side effect of statin treatment is rhabdomyolysis. In order to study the effect of statins in skeletal muscle cells, we used a DNA microarray analysis to investigate the changes in gene expression profiles brought about by statins in two skeletal muscle cell lines, namely, differentiated rat L6 myotubes and a human skeletal muscle cell line (hSkMC). In both cell lines, the statins (atorvastatin, cerivastatin and pitavastatin) induced the expression of four genes, which relate to cholesterol metabolism, namely, HMG-CoA synthase 1, HMG-CoA reductase, farnesyl diphosphate synthase and isopentenyl-diphosphate delta isomerase. Statin inhibited the synthesis of cholesterol at least five times more effectively in hSkMCs than in the hepatocytes. In addition, unlike in osteoblasts or coronary artery smooth muscle cells, statins upregulated the mRNA expression of cholesterol-associated enzymes in hSkMCs. These results provide basic information on skeletal muscle cells treated with statins and indicate that the cells are sensitive to the inhibition of HMG-CoA reductase, which may be related to the pathogenesis of muscle damage in statin therapy.

Mizoribine-induced Rhabdomyolysis in a Rheumatoid Arthritis Patient Receiving Bezafibrate Treatment

Bezafibrate, one of fibric acid derivatives, is widely used to treat hypertriglyceridemia and diabetic dyslipidemia. Fibric acid derivatives are known to induce rhabdomyolysis as a side effect, especially when given to patients with renal dysfunction. Mizoribine, an imidazole nucleoside, is used as an immunosuppressive agent. Here, we present a case of a patient with rheumatoid arthritis who developed rhabdomyolysis while undergoing treatment with mizoribine concomitantly with bezafibrate. Drug-induced rhabdomyolysis was suspected and bezafibrate and mizoribine were discontinued, and the patient was treated with hydration. The patient's symptoms rapidly disappeared and abnormalities of blood and urine test findings also improved to normal levels within 1 week. When prescribing fibrates to patients with high risk of renal damage, caution should be exercised regarding interactions with other drugs and the potential for inducing rhabdomyolysis.

Comparative pharmacokinetic interaction profiles of pravastatin, simvastatin, and atorvastatin when coadministered with cytochrome P450 inhibitors

Three-hydroxy-3-methylglutaryl coenzyme-A reductase inhibitors (statins) are first-line treatments for hypercholesterolemia. Although exceedingly well tolerated, treatment with statins incurs a small risk of myopathy or potentially fatal rhabdomyolysis, particularly when coadministered with medications that increase their systemic exposure. Studies compared the multiple-dose pharmacokinetic interaction profiles of pravastatin, simvastatin, and atorvastatin when coadministered with 4 inhibitors of cytochrome P450-3A4 isoenzymes in healthy subjects. Compared with pravastatin alone, coadministration of verapamil, mibefradil, or itraconazole with pravastatin was associated with no significant changes in pravastatin pharmacokinetics. However, concomitant verapamil increased the simvastatin area under the concentration:time curve (AUC) approximately fourfold, the maximum serum concentration (C(max)) fivefold, and the active metabolite simvastatin acid AUC and C(max) approximately four- and threefold, respectively (all comparisons p <0.001). Similar (greater than fourfold) important increases in these parameters and a >60% increase in the serum half-life (p = 0.03) of atorvastatin were observed when coadministered with mibefradil. The half-life of atorvastatin also increased by approximately 60% (p = 0.052) when coadministered with itraconazole, which elicited a 2.4-fold increase in the C(max) of atorvastatin and a 47% increase in the AUC (p <0.001 for C(max) and AUC). Clarithromycin significantly (p <0.001) increased the AUC (and C(max)) of all 3 statins, most markedly simvastatin ( approximately 10-fold increase in AUC) and simvastatin acid (12-fold), followed by atorvastatin (greater than fourfold) and then pravastatin (almost twofold). Pravastatin has a neutral drug interaction profile relative to cytochrome P450-3A4 inhibitors, but these substrates markedly increase systemic exposure to simvastatin and atorvastatin.

Flaccid quadriplegia due to necrotizing myopathy following lung transplantation

Critical illness myopathy (CIM) which is common after sepsis and multiorgan failure also has been described after organ transplantation. Prior reports of CIM after lung transplantation have not recorded a necrotizing myopathy. We present a 42-year-old man who developed a necrotizing critical illness myopathy following bilateral orthotopic lung transplantation. In addition we provide pathological confirmation that the ventral roots, spinal cord and the rest of the neuraxis are preserved in this condition. Extensive muscle necrosis is documented.