Structural formula of palbociclib/palbociclib

Palbociclib is a cyclin-dependent kinase (CDK) 4/6 inhibitor that has been approved in combination with endocrine therapy (ET) for the treatment of patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2) advanced breast cancer (ABC). Palbociclib is an oral capsule or tablet that patients typically take for 21 days with other medications, such as aromatase inhibitors or fulvestrant. This cycle repeats every 28 days as long as the patient responds to the drug and tolerates its side effects.

Palbociclib capsules or tablets for oral administration contain125 mg, 100 mg or 75 mg of the kinase inhibitor palbociclib with the molecular formula C24H29N7O2. The molecular weight is 447.54 Daltons. The chemical name is 6-acetyl-8-cyclopentyl-5-methyl-2-{[5-(piperazin-1-yl)pyridin-2-yl]amino}pyrido[2,3-d]pyrimidin-7(8H)-one. Palbociclibis a yellow to orange powder. At pH 4 or below, palbociclib appears as a highly soluble compound. When the pH value is higher than 4, the solubility of the API is significantly reduced.

Palbociclib capsules are usually taken with food, while tablets can be taken with or without food. Patients should take palbociclib at approximately the same time each day and not more or less often than prescribed by their doctor. Side effects caused by palbociclib may include increased infections, decreased red blood cell count, fatigue, stomach upset, hair loss, diarrhea, and mouth sores. Always discuss side effects with your doctor.