Coloring Agents in Pharmaceutical Industry

Coloring agents are used mainly to impart an elegant appearance, identification and protection to:

  • Tablet (coated or uncoated)
  • Oral liquid/ Hard & Soft gelatin capsules
  • Topical creams and ointments

Color Index Number (C.I. No.) is the identifier number of color “dye” or “lake”.

  • For Dye: C.I. No (***)
  • For Lake: C.I. No (*** : 1 )


  • Brilliant Blue FCF dye C.I. No = 42090
  • Brilliant Blue FCF lake C.I. No = 42090 : 1

Dyes vs Lakes

  • Dyes are soluble in water
  • Lakes are Insoluble in water


  • 21 CFR part 73, 74 & 82
  • Commission Regulation (EU) No 231/2012

3 main sources to set specification of dyes

  • 21 CFR Part 73 & 74

Common Tests of Dyes

  • Sum of volatile matter at 135 °C (275 °F) and chlorides and sulfates,
  • Water-insoluble matter,
  • Leuco base,
  • Impurities,
  • Subsidiary colors,
  • Chromium (as Cr),
  • Arsenic (as As),
  • Lead (as Pb),
  • Mercury (as Hg),
  • Total color, not less than 85 percent.

Common Tests of Lakes

Same tests like the color from which the lake is prepared.


  • Water-insoluble matter

and add two tests

  • Soluble chlorides and sulfates (as sodium salts), not more than 2.0 percent.
  • Inorganic matter, insoluble HCl, not more than 0.5 percent.

Analytical methods

  • In Combined Compendium Of Food Additive Specifications, volume 4
  • By Joint FAO/WHO Expert Committee on Food Additives (JECFA)

Coloring Agent in CTD File

As an Excipient, Information on Coloring agent used in a medicinal product should be provided in:

  • Part 3.2.P.1
  • Part 3.2.P.2
  • Part 3.2.P.4 and 3.2.A.3 of the CTD dossier.

Coloring Agents in Paediatric Preparations

In paediatric preparations, Coloring agents should be discussed and justified in terms of:

  • Allergenic potential,
  • Minimal toxicological implications,
  • Azo-dyes, like: (tartrazine, sunset yellow and new coccine) should be avoided in children’s medicines,
  • Natural colorants may cause allergic -reactions.

Read also:

Resource person: Raghda Fayed

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