Which statement best describes a CYP3A4-related warning involving Pimozide?

Which statement best describes a CYP3A4-related warning involving Pimozide?

• A. Avoid co-administration with drugs that inhibit CYP3A4
• B. Avoid co-administration with drugs that induce CYP3A4
• C. No CYP3A4 concerns with Pimozide
• D. CYP3A4 inhibitors increase Pimozide clearance

Answer: (A)

CYP3A4 interactions can change how much pimozide is in the blood. Pimozide is broken down mainly by the liver enzyme CYP3A4. If a drug that strongly inhibits this enzyme is taken with pimozide, the metabolism slows down, so pimozide levels rise. Higher levels raise the risk of QT prolongation and serious heart rhythm problems, so the precaution is to avoid co-administering pimozide with CYP3A4 inhibitors. Inducing CYP3A4 would speed up pimozide clearance and lower its levels, which isn’t the warning described here. The idea that there are no CYP3A4 concerns is incorrect, and saying inhibitors increase clearance is the opposite of how inhibition works.

CYP3A4 interactions can change how much pimozide is in the blood. Pimozide is broken down mainly by the liver enzyme CYP3A4. If a drug that strongly inhibits this enzyme is taken with pimozide, the metabolism slows down, so pimozide levels rise. Higher levels raise the risk of QT prolongation and serious heart rhythm problems, so the precaution is to avoid co-administering pimozide with CYP3A4 inhibitors.

Inducing CYP3A4 would speed up pimozide clearance and lower its levels, which isn’t the warning described here. The idea that there are no CYP3A4 concerns is incorrect, and saying inhibitors increase clearance is the opposite of how inhibition works.