Palbociclib Capsule: A Bioequivalence Study in Healthy Subjects Under Fed Conditions to Compare Two Formulations

Background: Globally, breast cancer is the most frequently diagnosed neoplasm among women, with an estimated 2.3 million new cases reported in 2022. Treatment for hormone receptor-positive (HR+) advanced breast cancer includes aromatase inhibitors and CDK4/6 inhibitors such as palbociclib. Objective: This study evaluated the bioequivalence and tolerability of two palbociclib capsule formulations to support the regulatory approval of a branded generic product in Latin America countries. Methods: Healthy participants were enrolled in an open-label, randomized, single-dose study using a two-treatment, two-sequence, two-period crossover design. Study participants received a single-dose test product, a palbociclib 125 mg capsule (Laboratório LKM S.A., Argentina), and a reference product, an Ibrance^® 125 mg capsule (Pfizer Manufacturing Deutschland GmbH), under fed conditions separated by a 14-day washout period. Blood samples were obtained at scheduled intervals over a 72 h period following administration, and the palbociclib plasma concentrations were determined using a validated LC-MS/MS method. Pharmacokinetic parameters were computed via non-compartmental analysis methods. A total of 52 healthy subjects were enrolled, and 50 subjects completed the study. Results: The geometric mean ratios (90% confidence intervals) for C_max and AUC_0-72 were 107.07% (101.98-112.42) and 109.77% (106.51-113.13), respectively. Conclusions: Both formulations were well-tolerated in healthy subjects. In accordance with regulatory standards, bioequivalence between the test formulation and the reference product was successfully demonstrated.