Tetracycline parenteral administration

Physicochemical incompatibilities are of particular concern when parenteral administration is planned. For example, certain insulin preparations should not be mixed. Similarly, the simultaneous administration of antacids or products high in metal content may compromise the absorption of many drugs in the intestine, eg, tetracyclines. The package insert and the Handbook on Injectable Drugs (see References) are good sources for this information. 

Parenteral Administration Doxycycline, the preferred parenteral tetracycline in the U.S., is indicated in severe ftlness, in patients unable to ingest medication, or when the oral drug causes nausea and vomiting. Tetracyclines should not be given intramuscularly because of local irritation and poor absorption. 

In food-producing animals, tetracyclines can be administered orally through feed or drinking water, parenterally, or by intramammary infusion. However, oral administration suppresses initially die ruminal fermentation of plant fiber. The absorption of tetracyclines can be further adversely affected by the presence of metallic ions in the gastrointestinal tract. All tetracyclines have an affinity for metallic ions and should not be administered with milk or high calcium levels in feed unless an upward adjustment in the dosage is made (226-228). 

ROUTES OF ADMINISTRATION AND DOSAGE A variety of tetracyclines are available for oral, parenteral, and topical administration. Tetracycline, oxytetracycline (TERRAMYCIN, others), demeclocycline (declomycin), minocycline (minocin, others), and doxycycline (vibramycin, others) are available in the U.S. 

The tetracyclines administered orally or parenterally may lead to the development of superinfections caused by strains of bacteria or fungi resistant to these agents. Pseudomembranous colitis due to overgrowth of toxin-producing C. difficile presents with severe diarrhea, fever, and stools containing mucous membrane neutrophils. Discontinuation of the drug, combined with the oral administration of metronidazole or vancomycin, usually is curative. 

The highest sales in humans and animals were f)-lactams and tetracyclines, respectively. Tetracyclines alone, in veterinary medicine, represented approximately 50.4% of all sales, while tetracyclines, sulfonamides/trimethoprim, P-lactams, and aminoglycosides combined accounted for more than 80% of AMDs used. During the 7-year period, sales of cephalosporins and fluoroquinolones in veterinary medicine increased by 38.4% and 31.6%, respectively. Nevertheless, as percentages of total veterinary sales, their use remained relatively small cephalosporins 0.64% and fluoroquinolones 0.33% in 2005. In animals, oral administration accounted for 88% of sales, and estimated sales for parenteral products were 10.5%. Moreover, while 92% of total tonnage was intended for food-producing animals, 64% of cephalosporins were intended for pets. 

In humans, contact with LPS may occur not only during a bacterial infection but also via LPS-contaminated medicaments and solutions administrated intravenously (parenteralia). Since the biological effects of LPS may appear even at concentrations of 1 ng per 1 kg of body weight, drugs intended for parenteral use, have to be endotoxin-free , i.e., thoroughly depyrogenated. In fact parenteralia have to comply with LPS threshold limits (in EU , endotoxin unit) regulated by pharmacopoeias. For example, tetracycline hydrochloride may not contain more than 0.5 ELf/mg. Similar limits exist for insulin (0.8 EU/insulin unit), hyaluronidase (2.3 EU/ hyaluronidase unit), the sodium salt ofheparin for injection (0.003 EU/heparin unit). ... 

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