CLS Statin Therapy & Pharmacology 3 — Questions and Answers
Question 1: Statin-associated muscle symptoms (SAMS) are most accurately defined as which of the following?
- Any myalgia occurring within 4 weeks of statin initiation regardless of CK level
- A spectrum from myalgia without CK elevation to rhabdomyolysis with CK >10× ULN (Correct answer)
- Muscle pain exclusively linked to CK elevation above 3× the upper limit of normal
- Myopathy confirmed by muscle biopsy showing mitochondrial rarefaction
Correct answer: A spectrum from myalgia without CK elevation to rhabdomyolysis with CK >10× ULN
SAMS encompasses the full spectrum from mild myalgia (normal CK) through myositis (CK elevation) to life-threatening rhabdomyolysis (CK >10× ULN with renal injury).
Question 2: The PREDICTION score or similar tools for statin myopathy risk account for which of the following as the strongest pharmacogenomic predictor of statin-induced myopathy?
- CYP2D6 poor metabolizer phenotype
- SLCO1B1 521T>C variant (rs4149056) (Correct answer)
- ABCB1 C3435T polymorphism
- CYP3A5 *3 allele
Correct answer: SLCO1B1 521T>C variant (rs4149056)
The SLCO1B1 521T>C variant reduces OATP1B1 transporter activity, impairing hepatic statin uptake and raising plasma concentrations, which significantly increases myopathy risk especially with simvastatin.
Question 3: A patient on atorvastatin 40 mg develops CK of 6× ULN without renal impairment or weakness. What is the recommended management?
- Immediately discontinue atorvastatin and never rechallenge
- Continue atorvastatin at the same dose and recheck CK in 6 weeks
- Hold atorvastatin, recheck CK weekly, and rechallenge with a lower dose once CK normalizes (Correct answer)
- Switch immediately to a high-intensity statin such as rosuvastatin 20 mg
Correct answer: Hold atorvastatin, recheck CK weekly, and rechallenge with a lower dose once CK normalizes
For asymptomatic CK elevation between 3–10× ULN without weakness, guidelines recommend withholding the statin, monitoring CK until normalization, and rechallenging at a lower dose or different statin.
Question 4: Which concomitant condition most dramatically increases the risk of statin-induced rhabdomyolysis independent of drug interactions?
- Well-controlled type 2 diabetes
- Hypothyroidism (Correct answer)
- Mild essential hypertension
- Stage 1 chronic kidney disease
Correct answer: Hypothyroidism
Untreated or undertreated hypothyroidism predisposes patients to myopathy and rhabdomyolysis, and statin therapy in this setting substantially amplifies that risk.
Question 5: Statin-associated autoimmune myopathy (SAAM) differs from typical SAMS because it is characterized by which finding?
- Resolution of symptoms within 2 weeks of statin discontinuation
- Persistent myopathy with anti-HMGCR antibodies after statin cessation (Correct answer)
- Normal CK with severe subjective fatigue and cramps
- Myopathy exclusively in patients on high-intensity statin doses
Correct answer: Persistent myopathy with anti-HMGCR antibodies after statin cessation
SAAM is an immune-mediated necrotizing myopathy driven by anti-HMGCR autoantibodies that persists and may worsen even after statin discontinuation, requiring immunosuppressive treatment.
Question 6: Which laboratory abnormality beyond CK elevation should prompt monitoring in patients on statin therapy, particularly those on higher intensity regimens?
- Serum potassium and sodium (electrolyte shifts)
- Alanine aminotransferase and aspartate aminotransferase (hepatotoxicity screening) (Correct answer)
- Serum uric acid (gout risk)
- Hemoglobin A1c (diabetes induction)
Correct answer: Alanine aminotransferase and aspartate aminotransferase (hepatotoxicity screening)
Although clinically significant statin hepatotoxicity is rare, baseline and periodic liver enzyme monitoring is recommended, especially when symptoms of hepatic dysfunction occur.
Question 7: Coenzyme Q10 (ubiquinone) supplementation has been proposed for statin-induced myalgia based on which pharmacologic rationale?
- Statins upregulate CoQ10 synthesis via an independent pathway requiring supplementation
- Statins inhibit the mevalonate pathway, reducing CoQ10 biosynthesis alongside cholesterol (Correct answer)
- CoQ10 directly inhibits HMGCR rebound expression induced by statins
- CoQ10 accelerates CYP3A4-mediated statin metabolism, reducing plasma levels
Correct answer: Statins inhibit the mevalonate pathway, reducing CoQ10 biosynthesis alongside cholesterol
Because CoQ10 is synthesized downstream of mevalonate via the same pathway statins block, statin use can reduce CoQ10 levels, potentially contributing to mitochondrial dysfunction in muscle.
CLS Statin Therapy & Pharmacology 3
Statin-associated muscle symptoms (SAMS) are most accurately defined as which of the following?