SLCO1B1 and Medicines

What is SLCO1B1?

When you take a medicine, your body needs way to handle it. One way is for drug transporters to carry the medicine to be broken down. A drug transporter called solute carrier organic anion transporter family member 1B1 (SLCO1B1) helps the body get rid of a class of medicines called statins. Statins include atorvastatin (Lipitor^®), fluvastatin, lovastatin, rosuvastatin (Crestor^®), pitavastatin, pravastatin (Pravachol^®), and simvastatin (Zocor^®).

How pharmacogenomic testing works

Each person differs from another at the DNA level. Genes are segments of DNA that act as a set of instructions and tell the body how to work. The SLCO1B1 gene is a section of DNA that instructs how well the SLCO1B1 transporter will work.

The study of how genes like SLCO1B1 affect the way your body interacts with medicines is called pharmacogenomics. Differences in your DNA that make up the SLCO1B1 gene can affect how well you are able to handle certain medicines.

If you transport medicine too fast or too slow, the medicine may not work as well, or you may have more side effects.

A pharmacogenomic test can help your medical team know how well the SLCO1B1 transporter will work. The test results can help your doctors and pharmacists choose the correct type or dose of medicine to give you. Please share your pharmacogenomic test results with all your new doctors and pharmacists.  

After pharmacogenomic testing

The results of your SLCO1B1 test will place you into 1 of 5 SLCO1B1 gene groups:

• Increased function – People in this group have slightly higher function of SLCO1B1 transporters. About 3% (3 in 100) of people are in this group.
• Normal function – People in this group have normal working SLCO1B1 transporters. About 66% (66 in 100) of people are in this group.
• Decreased function – People in this group have slightly lower functioning SLCO1B1 transporters. About 28% (28 in 100) of people are in this group.
• Poor function – People in this group have very low SLCO1B1 transporter function. People who are in this group may need lower doses or a different medicine to avoid side effects. About 3% (3 in 100) of people are in this group.
• Indeterminate phenotype – A small number of people will have unknown function of their CYP2D6 enzyme based on their test. About 1 in 1000 people are in this group.

The SLCO1B1 transporter helps in the breakdown of many medicines, including statins, medicines used to lower cholesterol levels. Depending on what gene group you are in, you may need a lower dose of some medicines or a different medicine.

Scientists continue to find new information about which medicines are affected by genes. Talk to your doctor or pharmacist if you have questions about your medicines, side effects, or pharmacogenomic testing.

Find more information about genes that are being used to make medication therapy decisions for patients at St. Jude.

If you have questions about pharmacogenomic testing done at St. Jude, you can email the Clinical Pharmacogenomics Program at pharmacogenomics@stjude.org.