The DRUGS that are usually employed or incorporated in our semi-solid preparations, usually elicits one or more FOUR GENERAL EFFECTS.

1. An EFFECT ON THE SKIN SURFACE or surface effects 2. EFFECTS WITHIN OUR STRATUM CORNEUM 3. A more DEEP-SEATED EFFECT which REQUIRES PENETRATION INTO YOUR EPIDERMIS AND DERMIS 4. SYSTEMIC EFFECT which usually results from delivering of sufficient drug passing through your epidermis to dermis and then to your vasculature or vascular system to produce therapeutic systemic concentration.