Which dosage form is a composition of liquid and powder that hardens when dry?

Which dosage form is a composition of liquid and powder that hardens when dry?

• A. Gels
• B. Plasters
• C. Transdermal patches
• D. Ointments

Answer: (B)

A plaster is a medicated paste that contains a liquid vehicle and finely divided powder, designed to dry and form a solid, adhesive film on the skin. When applied, the liquid component evaporates or the paste sets, causing it to harden and stay in place while delivering the drug locally. This drying-to-a-film behavior is what makes plasters distinct from other forms: gels are mostly liquid with a gelling agent and don’t harden into a film; transdermal patches are flexible adhesive films designed for controlled release; ointments are soft, greasy semisolids that do not harden after application.

A plaster is a medicated paste that contains a liquid vehicle and finely divided powder, designed to dry and form a solid, adhesive film on the skin. When applied, the liquid component evaporates or the paste sets, causing it to harden and stay in place while delivering the drug locally. This drying-to-a-film behavior is what makes plasters distinct from other forms: gels are mostly liquid with a gelling agent and don’t harden into a film; transdermal patches are flexible adhesive films designed for controlled release; ointments are soft, greasy semisolids that do not harden after application.