Which formulation offers the greatest potential for skin absorption?

Which formulation offers the greatest potential for skin absorption?

• A. Water soluble
• B. Emulsifiable concentrate
• C. Wettable powder
• D. Oil soluble

Answer: (D)

Skin absorption is greatest when a substance can dissolve in and partition into the skin’s lipid-rich outer layer, the stratum corneum. Oil-soluble compounds have a natural affinity for those lipids, so they penetrate the barrier more readily than water-soluble ones. Water-soluble formulations tend to stay in aqueous environments and don’t cross the lipid barrier as easily. Wettable powders are solid particles that must dissolve or remain on the surface, which limits penetration unless dissolution occurs. Emulsifiable concentrates use solvents to improve spread and penetration, but the fundamental driver of higher absorption is the active’s oil solubility. Therefore, oil-soluble formulations offer the greatest potential for skin absorption.

Skin absorption is greatest when a substance can dissolve in and partition into the skin’s lipid-rich outer layer, the stratum corneum. Oil-soluble compounds have a natural affinity for those lipids, so they penetrate the barrier more readily than water-soluble ones. Water-soluble formulations tend to stay in aqueous environments and don’t cross the lipid barrier as easily. Wettable powders are solid particles that must dissolve or remain on the surface, which limits penetration unless dissolution occurs. Emulsifiable concentrates use solvents to improve spread and penetration, but the fundamental driver of higher absorption is the active’s oil solubility. Therefore, oil-soluble formulations offer the greatest potential for skin absorption.