(e) Tinea unguium (ringworm of the nails). This fungus is caused by
an organism similar to the one which causes athlete's foot. Nails become thickened,
lusterless, and debris accumulates under the free edge of the nail. Eventually, the nail
may separate and come off. Treatment may be successful if griseofulvin is applied until
the nail has regrown completely and all infected material is gone. This process may
require six to twelve months.
(6) Systemic anti-infective agents. An anti-infective agent is a drug which is
used in the treatment or prevention of infections. These agents are also called
chemotherapeutic agents. Antibiotics and sulfonamides are two examples of these
agents. Broad spectrum antibiotics are effective against specific microorganisms in
both gram-positive and gram-negative classes. Narrow spectrum antibiotics affect only
a few microorganisms. The majority of these antibiotics are penicillin derivatives with a
specific spectrum for gram-positive organisms only. Included in anti-infective agents
are potassium penicillin G (injection and tablet form) and tetracycline tablets.
(a) Potassium penicillin G. Natural penicillins are derived from certain
species of molds and other fungi. They produce their effects by inhibiting biosynthesis
of cell wall mucopeptides. Therefore, all classes of penicillin are bacterial. Natural
penicillins are narrow spectrum antibiotics which are primarily effective against gram-
positive and a few gram-negative bacteria. The natural penicillins such as potassium
penicillin G are the first drug of choice in the treatment of infection caused by gram-
positive and a few gram-negative bacteria. Intramuscular injection of potassium
penicillin G provides maximal blood concentration within thirty to sixty minutes. The
action of the injection lasts a relatively short period of time which means that injections
are required every three to four hours to maintain sufficient medication in the blood.
The injection must be given deep into the muscle because of the frequency of injections
(b) Tetracycline tablets. Tetracycline is a broad spectrum antibiotic
effective against gram-positive and gram-negative bacteria. Tetracycline drugs
originate from strains of streptomycin containing broth that is fermented in deep tanks.
If this drug is administered orally, absorption takes place in the stomach and upper
portion of the small intestine. Tetracycline clears up the skin condition of acne pustules
by reducing the concentration of irritant fatty acids in the sebum. When used in the
treatment of acne, the dose is 250 mg every day or twice a day. DO NOT give
tetracyclines to children during tooth development. Caution anyone taking this drug to
avoid antacids, milk, dairy products, iron, or foods containing aluminum, calcium, or
magnesium.
d. Topical Antiparasitic Agents. These agents are destructive to itch mites
(scabicide). Both lice and mites of Sarcoptes scabiei are parasites that attack humans
and cause skin lesions. Lice bite the skin to obtain blood which they feed on. Leaving
their eggs and excrement on the skin, lice are passed on from person to person. The
Sarcoptes scabiei mite, barely visible with the naked eye, causes severe itching at
night. The disease scabies caused by this mite is usually acquired by sleeping with an
MD0575
5-15