MACHINES USED IN MANUFACTURING OF SEMISOLID DOSAGE FORM: 

SIZE REDUCTION APPARATUS
1.   Morter and pestle
2.   Hammer mill
3.   Ball mill
4.   Colloid mill
MIXING EQUIPMENTS
1.   Agitator mixers: sigma mixers and planetary
2.   Shear mixers: triple roller mill and collidal mill 
CENTRIFUGATION APPARATUS
1. Conical disc centrifuge or De laval clarifier
2. Supercentrifuge

 EVALUATION PARAMETER:SEMISOLID TOPICAL DOSAGE FORMS

Semisolid topical dosage forms include creams, ointments, and gels. In vitro drug release from semisolid topical dosage forms has been extensively investigated using the Franz cell diffusion system, with a synthetic membrane and to some extent using the enhancer cell.Depending on the solubility of the drug substance, the receptor medium may need to contain alcohol and/or surfactant. Deaeration is critical to avoid bubble formation at the interface with the membrane. A synthetic membrane often serves as an inert support membrane. Depending on the characteristics of the drug product, it may also be possible to conduct the in vitro test without a synthetic support membrane. As with transdermal products, the test temperature is typically set at 32°C to reflect the usual skin temperature. Deviations might be justified when products are for specific sites of action; for example, vaginal creams may be tested at 37°C. No compendial apparatus, procedures, or requirements for in vitro release testing of semisolid topical dosage forms have been described in relevant pharmacopeias to date. However, the FDA's Guidance for Industry on Scale Up and Post Approval Changes for Semisolid (SUPAC-SS) dosage forms describes the release rate studies using the vertical diffusion cell (Franz cell) procedure and requires in vitro release rate comparison between prechange and postchange products for approval of SUPAC-related changes.Because of the value and importance of release rate, it is highly desirable to determine the release data of semisolid dosage forms. There is also a need to develop compendial test method(s). It is expected that given the variety of formulations, sites of applications, and release rates for semisolid topical dosage forms, no single test procedure would be suitable for the development, biopharmaceutical characterization, and quality control of all semisolid topical dosage forms.

TRANSDERMAL PATCHES

Although several apparatus and procedures have been used to study in vitro release characteristics of transdermal patches, it is desirable to avoid unnecessary proliferation of dissolution test equipment. Current compendial apparatus include the paddle over disk/disk assembly method (USP apparatus 5/PhEur 2.9.4.1), the rotating cylinder (USP apparatus 6/PhEur 2.9.4.3), the reciprocating disk (USP apparatus 7), and a paddle over extraction cell method (PhEur 2.9.4.2).The paddle over disk procedure with a watch glass-patch-screen sandwich assembly is considered to be the method of choice, as it has been shown experimentally that this procedure results in almost the same release profile as other, more complicated apparatus for all US-marketed transdermal patches.The PhEur considers 100 rpm a typical agitation rate and also allows for testing an aliquot patch section.  pH of the medium ideally should be adjusted to pH 5 to 6, reflecting physiological skin conditions. For the same reason, the test temperature is typically set at 32°C (even though the temperature may be higher when skin is covered). The latter may be an appropriate means of attaining sink conditions, provided that cutting a piece of the patch is validated to have no impact on the release mechanism.