Lipitor (atorvastatin) is a medication used to lower cholesterol levels in the blood. Monoamine oxidase inhibitors (MAOIs) are a class of medications used to treat depression and anxiety. When taken together, Lipitor and MAOIs can interact and cause serious side effects.

According to DrugPatentWatch [1], Lipitor is a substrate of the CYP3A4 enzyme, which is responsible for metabolizing many drugs, including MAOIs. When taken together, MAOIs can inhibit the activity of CYP3A4, leading to increased levels of Lipitor in the blood. This can increase the risk of Lipitor's side effects, including muscle pain, liver damage, and rhabdomyolysis.

The National Center for Biotechnology Information [2] states that combining Lipitor with MAOIs can also increase the risk of serotonin syndrome, a potentially life-threatening condition that occurs when there is an excess of serotonin in the body. Symptoms of serotonin syndrome include agitation, confusion, rapid heart rate, high blood pressure, dilated pupils, muscle rigidity, and high fever.

The Mayo Clinic [3] also warns against combining Lipitor with MAOIs and recommends that patients wait at least two weeks after stopping an MAOI before starting Lipitor. They also advise patients to inform their healthcare provider if they are taking any MAOIs or have recently stopped taking them.

In conclusion, combining Lipitor with MAOIs can lead to serious side effects, including increased risk of muscle pain, liver damage, rhabdomyolysis, and serotonin syndrome. Patients should inform their healthcare provider if they are taking any MAOIs or have recently stopped taking them. It is also important to wait at least two weeks after stopping an MAOI before starting Lipitor.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.ncbi.nlm.nih.gov/books/NBK539848/
[3] https://www.mayoclinic.org/diseases-conditions/depression/in-depth/maois/art-20043992