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▪ The British Pharmacopoeia describes three water-miscible/removable bases:
a. Emulsifying Ointment BP (anionic)
b. Cetrimide Emulsifying Ointment BP (cationic)
c. Cetomacrogol Emulsifying Ointment BP (non-ionic)

Each of these contains:
• Liquid paraffin 20% w/w
• White soft paraffin 50% w/w
• Anionic, cationic or non-ionic emulsifying wax 30% w/w

Factors of Selecting Ointment Bases:
1. Physicochemical properties of the medicaments
2. Patient’s conditions
3. Intended site of application
4. Characteristics of the various vehicles available

General Guidelines
▪ Never use Volatile Solvents as levigating agents
▪ In preparing ointment by spatulation, the pharmacist works the ointment with a stainless
steel spatula but if the components react with metal the hard rubber is used
▪ Antibiotics are unstable in the presence of moisture - Use Anhydrous Ointment Base
▪ Use Mechanical Ointment Roller Mills or Electric Mortar and Pestle on large scale
(industry)

Test requirements for ointments :
▪ Ointments and other semisolid dosage forms must meet USP tests for microbial content,
minimum fill, packaging, storage, and labeling

(I) Microbial content:
▪ With the exception of ophthalmic ointments, topical preparations do not need to be sterile
but they must meet acceptable standards for microbial content, and preparations that are
prone to microbial growth must contain antimicrobial preservatives
▪ Among the antimicrobial preservatives used to inhibit microbial growth in topical
preparations are methylparaben, propylparaben, phenols, benzoic acid, sorbic acid, and
quaternary ammonium salts
▪ Preparations intended for urethral, vaginal and rectal use, should be tested for the presence
of yeast and molds which are common offenders of this area

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