What Is It?
ABCB1 (ATP-Binding Cassette subfamily B 1) aka Multi-Drug Resistance Protein 1 (MDRP1) codes for Pgp (Permeability glycoprotein) that pumps foreign substances out of the cells as a protective mechanism.
How does it affect your patients?
Variations in this gene can affect the absorption of many drugs. A good functional Pgp system decreases the efficacy of a drug where a patient might need an increase in dose
3435C>T
T/T allele:
- Pgp system works efficiently
- Drug absorption can be decreased
C/C allele
- Pgp system is deficient
- Drug absorption can be increased
Recommendations
A standard dose a medication may not be the same standard level of medication in the body due to Pgp system. Knowing how efficient or not the Pgp system works, can give insight if a dose may need to be decreased or increased due to rate of absorption.
Consider additive effects:
CYP2D6 PM + ABCB1 C/C Slowly metabolizing, rapidly absorbing. (Think of flooding your sink but not draining well) Concentration of a drug increases, therefore, a decrease in dose may be needed.
