General BP monograph Semi Solid preparations

Question 1

Several categories of semi-solid preparations for cutaneous application may be distinguished:

Answer 1

— ointments;
— creams;
— gels;
— pastes;
— poultices.

Depending on their structure, ointments, creams and gels generally show viscoelastic behaviour and are non-Newtonian in character, e.g. plastic, pseudoplastic or thixotropic type flow at high shear rates. Pastes frequently exhibit dilatancy.

Question 2

Topical Semi-solid Preparations - tests

Answer 2

Sterility
Uniformity of dosage units
uniformity of content
Uniformity of dose
Uniformity of delivered mass
Number of deliveries per container

Question 3

Topical Semi-solid Preparations - Labelling

Answer 3

The label states:
— the name of any added preservative;
— where applicable, that the preparation is sterile;
— for multidose containers, the period after opening the container after which the contents must not be used.

Question 4

Hydrophobic ointments are

Answer 4

Hydrophobic ointments can absorb only small amounts of water. Typical bases used for their formulation are hard, liquid and light liquid paraffins, vegetable oils, animal fats, synthetic glycerides, waxes and liquid polyalkylsiloxanes.

Question 5

Water-emulsifying ointments are

Answer 5

Water-emulsifying ointments can absorb larger amounts of water and thereby produce water-in-oil or oil-in-water emulsions after homogenisation, depending on the nature of the emulsifiers: water-in-oil emulsifiers (such as wool alcohols, sorbitan esters, monoglycerides and fatty alcohols), or oil-in-water emulsifiers (such as sulfated fatty alcohols, polysorbates, macrogol cetostearyl ether or esters of fatty acids with macrogols) may be used for this purpose. Their bases are those of the hydrophobic ointments.

Question 6

Hydrophilic ointments are

Answer 6

Hydrophilic ointments are preparations consisting of a basis that is miscible with water and that usually consists of a mixture of liquid and solid macrogols (polyethylene glycols). They may contain appropriate amounts of water.

Question 7

OINTMENTS are

Answer 7

Ointments are semi-solid preparations for cutaneous application consisting of a single-phase basis in which solids or liquids may be dispersed. They are supplied in single-dose or multidose containers.

Question 8

CREAMS are

Answer 8

Creams are semi-solid preparations of homogeneous appearance typically consisting of a lipophilic phase and an aqueous phase, one of which is finely dispersed in the other. They are supplied in single-dose or multidose containers

Question 9

Lipophilic creams are

Answer 9

In lipophilic creams, the continuous phase is the lipophilic phase. They usually contain water-in-oil emulsifiers (such as wool alcohols, sorbitan esters and monoglycerides).

Question 10

Hydrophilic creams are

Answer 10

In hydrophilic creams, the continuous phase is the aqueous phase. They contain oil-in-water emulsifiers (such as sodium or trolamine soaps, sulfated fatty alcohols, polysorbates and polyoxyl fatty acid and fatty alcohol esters) combined, if necessary, with water-in-oil emulsifiers.

Question 11

Gels are

Answer 11

Gels are semi-solid preparations for cutaneous application consisting of a single-phase liquid basis gelled by a suitable gelling agent. Active substance(s) are dissolved or dispersed in the basis. Gels are supplied in single-dose or multidose containers.

Question 12

Lipophilic gels are

Answer 12

Lipophilic gels (oleogels) are preparations whose bases usually consist of liquid paraffin with polyethylene or fatty oils gelled with colloidal silica or aluminium or zinc soaps.

Question 13

Hydrophilic gels are

Answer 13

Hydrophilic gels (hydrogels) are preparations whose bases usually consist of water, glycerol or propylene glycol gelled with suitable gelling agents (such as poloxamers, starch, cellulose derivatives, carbomers and magnesium-aluminium silicates).