The Pharmaceutics and Compounding Laboratory
Ointments: Preparation and
Evaluation of Drug Release

Ointment Bases

There are five (5) classes or types of ointment bases which are differentiated on the basis of their physical composition. These are:

  • oleaginous bases
  • absorption bases
  • water in oil emulsion bases
  • oil in water emulsion bases
  • water soluble or water miscible bases

Each ointment base type has different physical characteristics and therapeutic uses based upon the nature of its components. The following table summarizes the composition, properties, and common uses of each of the five types. For more information consult Remington's.

SUMMARY CHART: PROPERTIES OF OINTMENT BASES

  Oleaginous Ointment Bases

Absorption Ointment Bases

Water/Oil Emulsion Ointment Bases

Oil/Water Emulsion Ointment Bases

Water-miscible Ointment Bases

Composition oleaginous compounds oleaginous base + w/o surfactant oleaginous base + water (< 45% w/w) + w/o surfactant (HLB <8) oleaginous base + water (> 45% w/w) + o/w surfactant (HLB >9) Polyethylene Glycols (PEGs)
Water Content anhydrous anhydrous hydrous hydrous anhydrous, hydrous
Affinity for Water hydrophobic hydrophilic hydrophilic hydrophilic hydrophilic
Spreadability difficult difficult moderate to easy easy moderate to easy
Washability nonwashable nonwashable non- or poorly washable washable washable
Stability oils poor; hydrocarbons better oils poor; hydrocarbons better unstable, especially alkali soaps and natural colloids unstable, especially alkali soaps and natural colloids; nonionics better stable
Drug Incorporation Potential solids or oils (oil solubles only) solids, oils, and aqueous solutions (small amounts) solids, oils, and aqueous solutions (small amounts) solid and aqueous solutions (small amounts) solid and aqueous solutions
Drug Release Potential* poor poor, but > oleaginous fair to good fair to good good
Occlusiveness yes yes sometimes no no
Uses protectants, emollients (+/-), vehicles for hydrolyzable drugs protectants, emollients (+/-), vehicles for aqueous solutions, solids, and non-hydrolyzable drugs emollients, cleansing creams, vehicles for solid, liquid, or non-hydrolyzable drugs emollients, vehicles for solid, liquid, or non-hydrolyzable drugs drug vehicles
Examples White Petrolatum, White Ointment Hydrophilic Petrolatum, Anhydrous Lanolin, Aquabase™, Aquaphor®, Polysorb® Cold Cream type, Hydrous Lanolin, Rose Water Ointment, Hydrocream™, Eucerin®, Nivea® Hydrophilic Ointment, Dermabase™, Velvachol®, Unibase® PEG Ointment, Polybase™

*Varies depending upon specific content of the ointment base and the relative polarity of the drug(s) incorporated. This table refers more generally to the release of a typical nonelectrolyte (primarily lipophilic) drug.