We all know the common definition of semisolids like creams, ointments, gels etc. But do we know that in regulatory documents it is defined in different ways as per USP (United State Pharmacopoeia), CDER (Center for Drug Evaluation & Research), SUPAC-SS (Scale-Up and Post Approval Change Semisolids). This blog will highlight those points;

CDER Data:
Cream: A semisolid dosage form containing one or more drug substances dissolved or dispersed in a suitable base; more recently, the term has been restricted to products consisting of oil-in-water emulsions or aqueous microcrystalline dispersions of long chain fatty acids or alcohols that are water washable and more cosmetically and aesthetically acceptable.

Ointment: A semisolid preparation intended for external application to the skin or mucous membranes.

SUPAC-SS Guidance:
Cream: Semisolid emulsions that contain fully dissolved or suspended drug substances for external application.

Ointment: An unctuous semisolid for topical application. Typical ointments are based on petrolatum. An ointment does not contain sufficient water to separate into a second phase at room temperature. Water soluble ointments may be formulated with polyethylene glycol.

USP:
Cream: Creams are semisolid dosage forms containing one or more drug substances dissolved or dispersed in a suitable base. This term has traditionally been applied to semisolids that possess a relatively fluid consistency formulated as either water-in-oil or oil-in-water (emulsions. However, more recently the term has been restricted to products consisting of oil-in-water emulsions or aqueous microcrystalline dispersions of long-chain fatty acids or alcohols that are water washable and more cosmetically and aesthetically acceptable.

Ointment: Ointments are semisolid preparations intended for external application to the skin or mucous membranes..Ointment bases recognized for use as vehicles fall into four general classes: the hydrocarbon bases, the absorption bases, the water-removable bases, and the water-soluble bases. Each therapeutic ointment possesses as its base a representative of one of these four general classes.