Pharmaceutical Manufacturing Handbook: Production and

OINTMENTS AND CREAMS 279
FIGURE 1 Semisolid production machine with heat jacketed vessel, high - shear mixer,
scrapper, vacuum attachments, and control station. (Courtesy of Ross, Inc.)
operations. These equipments are supplied by various manufacturers, namely Bosch,
Bonafacci, Erweka, Fryma - Maschinenbau, IWKA, Kalish, and Norden.
Sterility of ointments, especially those intended for ophthalmic use, is achieved
by aseptic handling and processing. Improper processing, handling, packing, or use
of ophthalmic ointments lead to microbial contaminations and eventually result in
ocular infections. In general, the empty containers are separately sterilized and fi lled
under aseptic condition. Final product sterilization by moist heat sterilization or
gaseous sterilization is ineffective because of product viscosity. Dry - heat sterilization
is associated with stability issues. Strict aseptic procedures are therefore practiced
when processing ophthalmic preparations. Antimicrobial preservatives such as
benzalkonium chloride, phenyl mercuric acetate, chlorobutanol, or a combination
of methyl paraben and propyl paraben are included in ophthalmic ointments to
retain microbial stability.
Packaging An ideal container should protect the product from the external atmosphere
such as heat, humidity, and particulates, be nonreactive with the product
components, and be easy to use, light in weight, and economic [14] . As tubes made
of aluminum and plastic meet most of these qualities, they are extensively used for
packaging semisolids. Aluminum tubes with special internal epoxy coatings are
commercially available for improving the compatibility and stability of products.
Various modifi ed plastic materials are used for making ointment tubes. Tubes made