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Rglax Pharma

Coating defect

Moisture driven instability

Coated tablets pass release but drift on stability. Colour changes, assay falls, or degradation products rise.

Written by the Rglax Pharma technical team, who formulate and manufacture every grade named on this guide at our WHO-GMP works in Tahliwal, Una (drug manufacturing licence NNZ/23/238). Reviewed 3 September 2026. Licences and certificates.

What usually sits behind it

  • A film that covers but does not act as a barrier
  • A long open hold between coating and blistering
  • A core that was already carrying moisture before the coat went on

Worth knowing

Colour drift on early stability pulls is usually the first visible sign, ahead of any change in assay.

Every cause above is a process parameter, not a property of the material. If you are seeing moisture driven instability on a grade of ours, send us the run conditions and a retained sample and we will work back from them — start at the contact page.

Red pigment powder in a glass dish
Moisture driven instability, as it appears on a coated tablet. Illustration, not a photograph of production material.

Grades formulated against it

Where moisture driven instability is the problem the grade was made for

  • Moisture barrier for Amoxycillin and Clavulanate

    Solvent base extra white barrier film for the most moisture sensitive combination.

    Moisture barrier film coat on a solvent base, extra white, developed for Amoxycillin and Clavulanate potassium tablets. Water ingress during and after coating drives degradation in that combination, and this grade is built to hold it out.

    Base ·
    Non-aqueous (solvent)
    Finish ·
    Extra white, moisture barrier
    Formulated against ·
    Amoxycillin and Clavulanate potassium

  • Moisture barrier for multivitamin and ferrous tablets

    Solvent base barrier film for hygroscopic multivitamin and iron formulations.

    Solvent base moisture barrier film coat for Multivitamin and Ferrous group tablets. It protects the core from moisture pick-up and from the colour change that follows it on shelf.

    Base ·
    Non-aqueous (solvent)
    Finish ·
    Colour or white, moisture barrier
    Formulated against ·
    Multivitamins, Ferrous group

  • Extra white film coat for plain Amoxycillin

    Solvent base extra white film for plain Amoxycillin and dissolution critical tablets.

    Solvent base extra white film coat for plain Amoxycillin tablets and other products where dissolution has to be protected while the core is covered to a high opacity.

    Base ·
    Non-aqueous (solvent)
    Finish ·
    Extra white
    Formulated against ·
    Amoxycillin

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