Persistent use of against-label statin-fibrate combinations from 2003-2009 despite United States Food and Drug Administration dose restrictions

Analysis of Pharmacist Interventions Used to Resolve Safety Target of Polypharmacy (STOP) Drug Interactions

BACKGROUND

Statin drug interactions commonly increase the risk of muscle-related toxicities. The medical literature supports consultative pharmacist interventions to resolve drug interactions, but studies demonstrating autonomous pharmacist interventions are lacking.

OBJECTIVE

To evaluate the complementary impact of using pharmacist-led protocols and pharmacists with prescriptive authority to resolve statin drug interactions.

METHODS

Pharmacist-led protocols were developed to address gemfibrozil-statin and niacin-statin interactions. Pharmacists discontinued gemfibrozil and niacin by protocol or referred patients to the Patient Aligned Care Team (PACT) Pharmacy Clinic for individualized management. After all drug interactions were addressed, a retrospective quality improvement analysis was conducted. The primary outcome was to evaluate the impact of gemfibrozil and niacin discontinuation by protocol on patients' triglyceride (TG) laboratory results. The coprimary endpoints were the change in TGs and the percentage of patients with TGs ≥ 500 mg/dL, following pharmacist discontinuation by protocol. Secondary outcomes included the time required to resolve the interactions and a description of the PACT Clinical Pharmacy Specialists' (CPS) pharmacologic interventions.

RESULTS

The gemfibrozil and niacin protocols addressed 397 drug interactions. Seventy-six patients underwent gemfibrozil discontinuation by protocol and had TG laboratory results available. TG levels decreased or increased by < 100 mg/dL for 62 patients (82%), and 1 patient (1.3%) experienced TG elevation above the threshold of 500 mg/dL. Thirty-six patients had niacin discontinued by protocol and available laboratory results. The TG levels decreased or increased by < 100 mg/dL for 33 patients (91.7%), and no patients had TG levels increase above the threshold of 500 mg/dL. The mean time required to resolve both gemfibrozil and niacin drug interactions was 15.5 minutes per patient. A total of 129 patients were referred to the PACT Pharmacy Clinic to manage gemfibrozil and niacin drug interactions. TG laboratory results were available for 80 gemfibrozil patients (74.8%) and 16 niacin patients (72.7%). The PACT CPS made 171 pharmacologic interventions to address drug interactions and the median of 2 encounters per patient.

CONCLUSIONS

This single-site quality improvement analysis supports the complementary use of protocols and pharmacists with prescriptive authority to resolve statin drug interactions. These data support expanded roles for pharmacists, across settings, to mitigate select drug interactions.

Trends and variations in outpatient coprescribing of simvastatin or atorvastatin with potentially interacting drugs in Thailand

Background:

The aim of this study was to assess trends and variations in coprescribing of simvastatin or atorvastatin with interacting drugs in Thailand.

Methods:

Outpatient prescriptions between 2013 and 2015 in 26 tertiary care hospitals were analyzed for statin coprescribing. The proportion of patients exposed to coprescribing was estimated for semi-annual changes, using a time-series analysis and for hospital variations, using an interquartile range (IQR).

Results:

The coprescribing of simvastatin with all contraindicated drugs in 10 university and 16 general hospitals, respectively, was 3.6 and 3.1% in 2013, then decreased to 3.2 and 2.6% in 2014 and to 2.6 and 2.0% in 2015. The drug most frequently coprescribed with simvastatin, on a decreasing trend (by 0.19 percentage points) was gemfibrozil (in 2013, 2014 and 2015, respectively; 2.9, 2.3 and 2.0% in university hospitals, and 2.5, 2.0 and 1.6% in general hospitals). A similar trend was found in atorvastatin-gemfibrozil coprescribing. Patients coprescribed simvastatin with the rest of the contraindicated drugs were relatively stable at 0.6–0.8%. No protease inhibitors were coprescribed with simvastatin and atorvastatin. The IQR of simvastatin coprescribing in the university hospitals was smaller than that in the general hospitals and decreased over time.

Conclusions:

Coprescriptions potentially leading to drug interactions with simvastatin in Thailand were observed although the contraindicated drugs were acknowledged. Mutual awareness among health professionals and the implementation of electronic prescribing should be strengthened as zero drug interaction was possible as in the case of protease inhibitors in the present study.

Clinical Pharmacist Patient-Safety Initiative to Reduce Against-Label Prescribing of Statins With Cyclosporine

BACKGROUND

Against-label prescribing of statins with interacting drugs, such as cyclosporine, represents an important patient safety concern.

OBJECTIVE

To implement and evaluate the effectiveness of a clinical pharmacist patient-safety initiative to minimize against-label prescribing of statins with cyclosporine.

METHODS

Kaiser Permanente Colorado clinical pharmacists identified patients receiving both cyclosporine and against-label statin through prescription claims data. Academic detailing on this interaction was provided to health care providers. Clinical pharmacists collaborated with physicians to facilitate conversion to on-label statin. Conversion rates along with changes in low-density lipoprotein cholesterol (LDL-C) were assessed.

RESULTS

Of the 157 patients identified as taking cyclosporine, 48 were receiving concurrent statin therapy. Of these 48 patients, 33 (69%) were on an against-label statin regimen; 25 (76%) of these patients were converted to on-label statin. Overall, patients converted to on-label statin had a mean LDL-C prior to conversion of 82.9 (±26.4) mg/dL and mean LDL-C after conversion of 90.7 (±31.2) mg/dL ( P = 0.21). In all, 17 patients (68%) were switched to pravastatin 20 mg daily and 8 patients (32%) to rosuvastatin 5 mg daily. In patients converted to pravastatin 20 mg daily, the mean LDL-C was 13.5 mg/dL higher than prior to conversion ( P = 0.066). In patients converted to rosuvastatin 5 mg daily, the mean LDL-C was 3.8 mg/dL lower than prior to conversion ( P = 0.73).

CONCLUSION

Utilizing a patient-safety-centered approach, clinical pharmacists were able to reduce the number of patients on against-label statin with cyclosporine while maintaining a comparable level of LDL-C control.

Simvastatin prescribing patterns before and after FDA dosing restrictions: a retrospective analysis of a large healthcare claims database

BACKGROUND

Muscle-related events, or myopathies, are a commonly reported adverse event associated with statin use. In June 2011, the US FDA released a Drug Safety Communication that provided updated product labeling with dosing restrictions for simvastatin to minimize the risk of myopathies.

OBJECTIVE

Our objective was to describe prescribing patterns of simvastatin in combination with medications known to increase the risk of myopathies following updated product labeling dosing restrictions in June 2011.

METHODS

A retrospective observational analysis was carried out, in which administrative claims data were utilized to identify prescribing patterns of simvastatin in combination with calcium channel blockers (CCBs) and other pre-specified drug therapies. Prescribing patterns were analyzed on a monthly basis 24 months prior to and 9 months following product label changes. Incidence of muscle-related events was also analyzed.

RESULTS

In June 2011, a total of 60% of patients with overlapping simvastatin-CCB claims and 94% of patients with overlapping simvastatin-non-CCB claims were prescribed an against-label combination. As of March 2012, a total of 41% and 93% of patients continued to be prescribed against-label simvastatin-CCB and simvastatin-non-CCB combinations, respectively. The most commonly prescribed dose of simvastatin was 20 mg (39%). Against-label combinations were most commonly prescribed at a simvastatin dose of 40 mg (56%). Amlodipine was the most commonly prescribed CCB in combination with simvastatin (70%) and the most common CCB prescribed against-label (67%).

CONCLUSIONS

Despite improvements in prescribing practices, many patients are still exposed to potentially harmful simvastatin combinations. Aggressive changes in simvastatin prescribing systems and processes are needed to improve compliance with FDA labeling to improve medication and patient safety.

Assessment of statin-associated muscle toxicity in Japan: a cohort study conducted using claims database and laboratory information

OBJECTIVE

To estimate the incidence of muscle toxicity in patients receiving statin therapy by examining study populations, drug exposure status and outcome definitions.

DESIGN

A retrospective cohort study.

SETTING

16 medical facilities in Japan providing information on laboratory tests performed in and claims received by their facilities between 1 April 2004 and 31 December 2010.

PARTICIPANTS

A database representing a cohort of 35 903 adult statin (atorvastatin, fluvastatin, pitavastatin, pravastatin, rosuvastatin and simvastatin) users was studied. Use of interacting drugs (fibrates, triazoles, macrolides, amiodarone and ciclosporin) by these patients was determined.

MAIN OUTCOME MEASURE

Statin-associated muscle toxicity (the 'event') was identified based on a diagnosis of muscle-related disorders (myopathy or rhabdomyolysis) and/or abnormal elevation of creatine kinase (CK) concentrations. Events were excluded if the patients had CK elevation-related conditions other than muscle toxicity. Incidence rates for muscle toxicity were determined per 1000 person-years, with 95% CI determined by Poisson regression.

RESULTS

A total of 18 036 patients accounted for 42 193 person-years of statin therapy, and 43 events were identified. The incidence of muscle toxicity in the patients treated with statins was 1.02 (95% CI 0.76 to 1.37)/1000 person-years. The estimates varied when outcome definitions were modified from 0.09/1000 person-years, which met both diagnosis and CK 10× greater than the upper limit of normal range (ULN) criteria, to 2.06/1000 person-years, which met diagnosis or CK 5× ULN criterion. The incidence of muscle toxicity was also influenced by the statin therapies selected, but no significant differences were observed. Among 2430 patients (13.5%) received interacting drugs with statins, only three muscle toxicity cases were observed (incidence: 1.69/1000 person-years).

CONCLUSIONS

This database study suggested that statin use is generally well tolerated and safe; however, the risk of muscle toxicity related to the use of interacting drugs requires further exploration.

Patterns of serum laboratory monitoring for safety and efficacy in patients on chronic statin therapy

OBJECTIVE

To describe safety and efficacy laboratory monitoring of statin therapy at the University of Colorado Hospital Outpatient Clinics over a period of 3 years prior to the revised United States Food and Drug Administration statin labeling.

METHODS

This retrospective, observational study evaluated serum laboratory monitoring for safety and efficacy of statin therapy between July 2008 and June 2011. Adult patients prescribed chronic statin therapy were included. The primary objective of this study was to describe the frequency of outpatient liver function tests, lipid panels, and creatine kinase for patients on chronic statin therapy.

RESULTS

A total of 143 patients met study criteria. Over a 3-year period, the mean maximum frequency of measurements per patient of serum hepatic transaminases, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) was higher than lipid panel measurements (5.2 ± 4.4 and 4.2 ± 2.0 respectively, p = 0.021). Only 22 of 143 patients (15.4%) had an elevation in ALT or AST. All elevations were less than three times the upper limit of normal and statin therapy was continued without changes in response to these elevations. Creatine kinase, though not a routine monitoring test, was infrequently measured (mean maximum frequency of measurements per patient 0.3 ± 0.8).

CONCLUSION

Serum hepatic transaminases were routinely monitored in patients treated with chronic statin therapy. Given the absence of significant serum hepatic transaminase elevations, and clinician response to minor elevations, our data indicate that routine serum laboratory evaluations for statin toxicity are excessive.