The influence of electrostatic properties on the punch sticking propensity of pharmaceutical blends

Leila Samiei, Karen Kelly, Lisa Taylor, Ben Forbes, Elizabeth Collins, Martin Rowland

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)
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The present study details characterisation of the electrostatic properties of a range of active pharmaceutical ingredients (APIs) and blends and investigates the role of electrostatics as a potential root cause of punch sticking during tabletting.

Microcrystalline cellulose (AVICEL® PH-102) and magnesium stearate were used to prepare blends of constant drug loading (10% w/w) with a range of APIs. The electrostatic properties of the APIs and blends were then determined using a JCI Chilworth 155v6 Charge Decay Time Analyser (CDTA) under controlled environmental conditions. The measurements recorded were then correlated to a punch sticking assessment of each blend, which was obtained utilising a Material Adhesion Screen for Sticking (MASS) Punch.

The APIs became electrostatically charged to a higher extent than the blends. The linear relationship between particle punch sticking and the maximum surface voltage (Vs) attained post charging was poor (R2 = 0.58). However, a reduction in the susceptibility of the blend to retain electrostatic charge, as determined by the measurement of charge decay times (Time 1/e and Time 10%), was found to be linearly proportional (R2 = 0.89 and 0.88 respectively) to the sticking propensity.

Despite the excipients significantly damping the charging propensity of the API in a formulation, the electrostatic behaviour and punch sticking propensity of the majority of the formulated blends were shown to be dominated by the API (even at only 10% w/w). It is anticipated that the use of formulations with fast charge decay rates may reduce sticking problems during tablet production.
Original languageEnglish
Pages (from-to)509-517
Number of pages9
Early online date11 Oct 2016
Publication statusPublished - 1 Jan 2017


  • Triboelectrification
  • Electrostatic charge
  • Sticking
  • Direct compression


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