(11) Topical--refers to the method of administering medicine. Topical
application means that the medicine was applied directly on the skin.
In today's society, there are legitimate and not so legitimate uses of drugs.
Listed below are some of the legitimate uses:
a. To Maintain Health. Vitamins and minerals are used and abused in the
pursuit of good health.
b. To Reverse a Disease Process. Antibiotics and chemotherapeutic agents
are commonly used in medicine today to cure diseases.
c. To Relieve Symptoms. Drugs which act to relieve symptoms do not cure the
patient. Instead, they help make the patient more comfortable in order for him to work
or function. The assumption is that the body will cure itself.
d. To Prevent Disease. Vaccines and toxoids are widely used to prevent
disease. In the 1940s and 1950s, many parents kept their children home to avoid polio.
Today, most parents think of polio only when they take their children for the periodic
(and necessary) vaccination for this still- present threat. Also, children today do not
normally become ill with measles; instead, they are vaccinated for measles.
FACTORS AFFECTING SURFACE DRUG ABSORPTION
Many factors affect how the application of a particular drug will be absorbed by
the skin surface.
a. Skin Permeability.
(1) Skin is durable because of the dermis, which is composed of connective
tissue made up of fibers. Skin is selectively permeable; that is, skin allows only certain
substances to enter the pores. The stratum corneum, the first layer of the epidermis, is
a dense layer made up of dead, flattened cells that are filled with keratin (an insoluble
protein). This layer of dead cells resists substances that are water-soluble or fat-
soluble. In other words, the stratum corneum acts as the raincoat of the skin. If the
epidermis is removed, the deeper layers of living cells, the dermis, act as a barrier to
keep out fat-soluble substances.
(2) Because the skin has an oily secretion, medication applied to the skin
surface is absorbed best if such medication is suspended or dissolved in oily media.
Drugs combined with inorganic substances such as petroleum are not absorbed as well
as drugs combined with synthetic ointment bases that are like sebaceous secretions.