SLCO1B1 Genotyping

SLCO1B1 (also known as OAT1B1) is an influx transporter that moves drugs into cells. Variations in SLCO1B1 may affect the blood levels of drugs that are substrates for this transporter.[61] Statins are one of the most common classes of medications affected by this transporter, other medications include angiotensin-converting enzyme (ACE) inhibitors and methotrexate.[62]

Variations that result in decreased transporter activity may result in increased statin blood levels and increase the risk of adverse effects, such as myalgia and rhabdomyolysis. SLCO1B1-based dosing guidelines are available for statins.[63] Providers should consider genotyping patients who are initiating statin therapy or those who have experienced adverse effects to statins in the past. Genetic variants tested for SLCO1B1 are *1B,*5,*9,*14,*15,*17,*31,*35.

Indications for SLCO1B1 Testing

Any patient taking a simvastatin (Zocor®) dose of greater than or equal to 40 mg per day, or any individual with a personal or family history of adverse effects to medications that are substrates of SLCO1B1 are appropriate candidates for testing. Other statins that must be monitored closely and have their doses limited include atorvastatin (Lipitor®), rosuvastatin (Crestor®), pravastatin (Pravacol®) and lovastatin (Mevacor®). SLCO1B1 genotyping may also be useful in confirming the presence of variant genotypes that affect the metabolism of SLCO1B1 transported drugs.