structure and chemical activity. The most important mechanism of action of the tetracycline is blocking the formation of polypeptides used in protein synthesis. Because of their broad spectrum of activity, tetracycline are most valuable in the treatment of mixed infection, such as chronic bronchitis and peritonitis; however, they are drugs of choice for only a few bacterial infections. Tetracycline is also used as a topical preparation in the treatment of acne.
The tetracycline are relatively non-toxic, the most common side effects being mild gastrointestinal disturbances; allergic reactions and anaphylaxis are rare. Administration to children and pregnant women is not indicated because it may produce discoloration of the teeth and depress bone marrow growth. The major hazard of tetracycline therapy is the overgrowth of resistant organisms, especially Monilia and staphylococci.
Tetracycline should not be administered with milk, milk products, antacids or iron preparations; they combine with metal ions to form nonabsorbable compounds.
ACTION AND USE. Tetracycline hydrochloride (TCN) is used in the treatment of infections caused by Rickettsiae (Rocky Mountain spotted fever, typhus fever), agent of lymphogranulomas venereum and granuloma inguinale, and the spirochetal agent of relapsing fever. It is also indicated for certain gram-negative microorganisms. Tetracycline hydrochloride is indicated for severe acne as an adjunctive therapy. Food and some dairy products may interfere with absorption; antacids containing aluminum, calcium, or magnesium impair absorption of the antibiotic as well. Give the drug 1 hour before or 2 hours after meals.
USUAL DOSE. 1 or 2 grams per day in two or four equal doses, depending on the severity of the infection.
ACTION AND USE. Doxycycline is active against a wide range of gram-positive and gramnegative microorganisms and has a low affinity for binding with calcium. In addition to the conditions listed under tetracycline, doxycycline is also indicated for the treatment of uncomplicated chlamydial infections and uncomplicated gonococcal infections.
USUAL DOSE. For most uncomplicated infections, 200 mg the first day followed by a maintenance dose of 100 mg per day for 7 to 10 days. For venereal diseases, 200 mg per day for 7 days in equally divided doses; for syphilis, 300 mg per day in equally divided doses for 10 days. Intravenous infusion is indicated only when the oral route is not indicated.
ACTION AND USE. Minocycline hydrochloride is indicated for the same conditions as tetracycline hydrochloride and doxycycline hyclate.
USUAL DOSE. The dosage ranges are the same as for doxycycline hyclate.
The aminoglycosides are a group of drugs sharing chemical, antimicrobial, pharmacologic, and toxic characteristics. They are effective against most gram-positive and gram-negative organisms; the method of action is by inhibiting protein synthesis. Aminoglycosides can cause varying degrees of otototicity and nephrotoxicity, depending on the particular agent and the dose. Toxicity is more prevalent in the presence of renal impairment, in the very young or old, dehydration, or with the use of diuretics. Because of their high toxicity, they are not recommended when the infective organism is susceptible to less toxic preparations.
ACTION AND USE. Streptomycin sulfate is indicated for all forms of mycobacterium tuberculosis; it should be used only in conjunction with other antituberculosis drugs, i.e., rifampin or isoniazid. It is also indicated in the treatment of plague, tularemia, chancroid, granuloma inguinale and some urinary tract infections where the infectious agent has shown to be susceptible to streptomycin and not susceptible to less toxic preparations.
USUAL DOSE. The dosage ranges from 1 to 4 g daily depending on the disease condition and the condition and age of the patient. Streptomycin is for intramuscular use only.