Objective is to characterize the relationship between genetic polymorphisms and inter-individual variability in plasma statin and metabolite concentration(s) and to quantify its contribution towards clinically significant statin induced muscle ADR phenotypes myopathy and/or myalgia in Singapore population. Methodology: This research involves the study of two different kinds of muscle ADRs commonly associated with statin therapy, namely myalgia and myopathy. The study of myalgia will include the recruitment and sample collection (blood)from 3000 subjects from the outpatient clinic at NUH and NHC, who are on either simvastatin or atorvastatin. To identify genetic variants associated with altered stain exposure, investigators will perform an analysis of the drug and metabolite levels in plasma, followed by a genetic analysis of DNA from the blood samples of the recruited subjects. A subgroup of 30 subjects (15 from NUH and 15 from NHC) from this large cohort will be used to study intra-subject variability in statin drug and metabolite exposure. The genetic association analysis of genotype and statin blood measurements will be done using liner regression analysis. To test the hypothesis that related pharmacokinetic variants are associated with myalgia and myopathy, investigators will perform the case-control association analysis using logistic regression to examine the frequency of genetic variant in patients with clinically identified ADRs and compare it to control subjects without any ADRs. A separate cohort of 200 subjects will be recruited for the myopathy study through the NUH outpatient clinic following subject identification through an IRB approved medical records review of patients who were/are any statin drug/dose. Blood samples collected from these patients will be subjected to genetic analysis to identify genetic variants associated with symptomatic phenotypes.
Potential Benefits and risks: The potential benefits of this study include, identifying strong risk factors of statin induced muscle symptoms myalgia/myopathy that should inform clinical practice in minimizing/ managing severity of statin associated muscle symptoms, by identifying patient populations with an increased risk to statin induced myalgia and/or myopathy. This information might ultimately inform treatment decisions including drug selection and dosing and improved prediction of treatment response in a heterogeneous population. The only possible risk in the study is that associated with blood-taking. Obtaining blood can cause pain, bleeding, bruising, or swelling at the site of the needle stick. Fainting sometimes occurs and infection rarely occurs.