Definition:
Semi-solid dosage forms are dermatological preparations intended to be applied externally
on the skin to produce local or systemic effects e.g. ointments, creams, gels,
and pastes. They contain one or more active ingredients dissolved or uniformly
dispersed in a suitable base and any suitable excipients such as emulsifiers,
viscosity-increasing agents, antimicrobial agents, antioxidants, or stabilizing
agents. Semisolids can adhere to the application surface for sufficiently long
periods before they are washed off. This property helps prolong drug delivery
at the application site. Novel semisolids are non-greasy since they are made up
of water-washable bases. Hence, they cause less irritation to the skin and are superior
to conventional semisolid dosage forms.
1. Physical Properties
- They should have a smooth texture.
- They should be elegant in appearance.
- They should be non-dehydrating.
- They should be non-gritty in nature.
- Semi-solid dosage forms possess non-greasy and non-staining properties.
- They are non-hygroscopic in nature.
2. Physiological Properties
- They should be non-irritating.
- They should not alter skin functioning.
- They should be easily miscible with skin secretion.
- They should have a low sensitization effect.
3. Application Properties
- They should be easily applicable with efficient drug release.
- They should possess high aqueous washability.