Pilot Study of Cyclobenzaprine for Treatment of Sleep Disturbance in Aromatase Inhibitor-treated Breast Cancer Patients

UMCC 2013.051: Prospective Pilot Study Evaluating the Use of Cyclobenzaprine for Treatment of Sleep Disturbance, Fatigue, and Musculoskeletal Symptoms in Aromatase Inhibitor-treated Breast Cancer Patients

Many women with breast cancer who are treated with aromatase inhibitor medications develop difficulty sleeping and fatigue during treatment. Some examples of aromatase inhibitor medications include anastrozole (Arimidex), exemestane (Aromasin), and letrozole (Femara). Frequently, sleeping pills do not work very well to improve sleep. Cyclobenzaprine (Flexeril) is a medication that was originally developed to treat muscle spasms. It may also improve sleep in patients with chronic pain disorders, such as fibromyalgia. In this study we are testing to see if cyclobenzaprine at bedtime will help improve sleep in women treated with aromatase inhibitors.

Inclusion Criteria:

• Female gender, age ≥ 18, postmenopausal.
• Histologically proven stage 0-III invasive carcinoma of the breast
• Initiating or have been receiving a standard dose of aromatase inhibitor therapy (letrozole 2.5mg once daily or exemestane 25mg once daily or anastrozole 1mg once daily) for up to a total of 48 months of AI therapy.
• Trouble sleeping during the past week. (After signing the informed consent document, subjects must also have a global PSQI score of ≥5)
• ECOG performance status 0-2 (see Appendix A).

Exclusion Criteria:

• Known hypersensitivity to cyclobenzaprine or any of the inactive ingredients
• Diagnosis of sleep apnea that is currently interfering with sleep or requiring CPAP, restless leg syndrome that is currently interfering with sleep or requiring medication, or Epworth sleepiness scale >10.
• Subjects with a history of hypothyroidism must have been on a stable dose of thyroid replacement medicine for at least 3 months prior to enrollment
• Treatment with steroids within 1 month
• Treatment with monoamine oxidase inhibitors (MAO-I) within 14 days of enrollment.
• Concurrent treatment with bupropion, MAO inhibitors, phenothiazines (including thioridazine), selegiline, tramadol, or medications known to prolong the QT interval (www.azcert.org/medical-pros/drug-lists/drug-lists.cfm)
• Currently primary psychiatric diagnosis (schizophrenia, psychosis) or suicidal ideation, history of bipolar disorder, or seizure disorder
• Known moderate or severe hepatic impairment
• History of congestive heart failure or cardiac arrhythmia (other than atrial fibrillation); myocardial infarction within the past 6 months
• Uncontrolled narrow-angle glaucoma
• Pregnant or breast feeding
• Serious or unstable medical condition that could likely lead to hospitalization during the course of the study or compromise study participation