is myopathy part of statin therapy (imposter-16)

Conditions: Myopathic Conditions

Summary: there is a significant proportion of patients complaining of muscle symptoms while on statin therapy who have a measurable difference in muscle strength or endurance and whose muscle biopsies are diagnostic for myopathy.

this is a double-blinded, randomized, placebo-controlled, crossover trial. sixty patients who are identified by their physician as having muscle pain or weakness while on statin therapy and in whom creatine kinase (ck) enzyme determinations have been normal will be enrolled voluntarily. all patients will have a percutaneous muscle biopsy prior to enrollment into the trial. these patients will be randomized in a blinded crossover fashion to either standardized statin therapy or placebo in eight week intervals. after eight weeks of drug or placebo the patients will be assessed for signs and symptoms of muscle weakness by: * dynamometry of grip and hip strength * an exercise test with exhaled gas analysis * blood tests for cholesterol, creatine kinase, lactate * urine tests for organic acids following the first eight-week study and testing period, each patient will serve as their own control and they will enter a second eight-week study period. during the second phase they will take the opposite therapy, either drug or placebo, which they have not yet received. sub-studies will include ten controls who have never previously received statins and ten subjects who have suffered statin-induced rhabdomyolysis. subjects in these sub-studies will not be exposed to statin therapy and will only undergo limited testing.

Eligibility criteria:
inclusion criteria: * primary doctor's permission * patient understands nature of study and has signed consent * patient is \>21 years of age * patient willing to stop statin for up to 12 weeks and remain off coq10 for study duration * patient able to perform the strength and functional tests required * patient complains of muscle weakness or aching which he/she or his/her physician feels may be attributable to statin therapy * ck \< 350 iu * thyroid stimulating hormone (tsh) must be normal * fasting respiratory exchange ratio (rer) \> 0.80 off statin for at least 4 weeks exclusion criteria: * severe underlying illness including: cr \> 3.0, liver failure, unstable angina, symptomatic valvular heart disease, congestive heart failure, or prior cerebrovascular accident (cva) preventing exercise testing. * history of muscle damage (ck \> 350 iu) on statins * underlying musculoskeletal disorder preventing muscle testing * history of severe depression * taking doses of other medicines with statin sufficient to cause myopathy including: cyclosporine, erythromycin or other macrolide antibiotics; fluconazole; niacin; fibrates; or \> 16 oz. of grapefruit juice daily. * diabetes requiring other than diet therapy * use of thiazolidinediones (tzd's), protease inhibitors or other drugs known to influence rer or fatty acid oxidation. * abnormal thyroid status * inability to maintain constant exercise, dietary, and drug regimen during the 16 weeks required by the study protocol.

Keywords: rhabdomyolysis, myositis, myopathy, statin side effects, fatty acid oxidation statin induced muscle toxicity