Most drug products cannot be manufactured without the use of excipients [1,2]. Excipients serve a wide range of functions, from stabilizing the active pharmaceutical ingredients (API) to enabling manufacturability and enhancing the texture and taste of the final product [3,4]. Each excipient plays a unique role in the formulation of various dosage forms, making it important to understand excipient functionality early in the formulation development process [5]. This understanding helps prevent potential negative consequences arising from excipient misuse [6]. Additionally, from a regulatory standpoint, a clear classification of excipient functions not only justifies excipient selection but also supports the development of appropriate excipient evaluation methods [7].

To produce tablets of acceptable quality by compression, a formulation must meet several essential criteria: 1) adequate flowability to ensure consistent and reproducible die filling [8]; 2) sufficient interparticle bonding to form mechanically strong tablets upon compression [9]; 3) low ejection force to prevent damage to both the tablets and tooling [10]; and 4) freedom from punch sticking to enable efficient manufacturing [11]. Because most APIs do not possess all of these characteristics, excipients are essential to ensure the successful manufacturing of high-quality tablets [12,13]. In this context, lubricants are commonly incorporated to reduce ejection forces [10,14], whereas anti-adherents are used to mitigate punch sticking [15].

Since lowering ejection forces and preventing punch sticking are distinct objectives in tablet manufacturing, it is essential to differentiate the functions of lubricants and anti-adherents [16]. Some commonly used lubricants, such as magnesium stearate, can perform both functions [11,17]. This dual functionality has contributed to the widespread but incorrect assumption that lubricants inherently possess anti-sticking properties [[18], [19], [20]]. As a result, there is often an unwarranted expectation that lubricants alone can prevent punch sticking [21,22]. Although it is conceivable that a lubricant does not necessarily act as an anti-adherent, no systematic studies have been published to substantiate this distinction. In this work, we show that, while effective in reducing ejection force, a lubricant may induce severe punch sticking issues, contrary to the expected role of an anti-adherent.