Tetracycline Hydrochloride (Oral)
Tetracycline has its main mechanism of action on protein synthesis, and an energy-dependent active transport system pumps the drug through the inner cytoplasmic membrane of bacteria. Once inside the bacterial cell, Tetracycline binds specifically to the 30s ribosomes and inhibit bacterial protein synthesis.Many Gram positive aerobic Cocci are susceptible, but many strains of staphylococci, streptococci and even some pneumococci are resistant to Tetracycline. Thus, tetracycline is not the drug of choice in infections due to gram positive aerobes.Pseudomonas and many Enterobacteriaceae are resistant. Urinary concentrations are adequate for some community - acquired E. coli and consequently, Tetracycline is still used in uncomplicated initial UTIs. Tetracycline is also active against and is the drug of choice for Brucella species, Calymmatobacterium granulomatis, Vibrio cholerae and V. vulnificus.Tetracycline is also active against anaerobic species of bacteria and since concentrations of the drug are quite high in the gastrointestinal contents, the enteric flora are usually altered by the drug.Tetracycline is incompletely absorbed from the gastro-intestinal tract, about 60 to 80% of a dose of tetracycline usually being available. It is widely distributed through the body tissues and fluids.Tetracycline has a half-life of about 12 hours. It is excreted in the urine and in the faeces.
The usual adult oral dosage of Tetracycline is 1-2 g daily given in 2-4 divided doses. The usual oral dosage of Tetracycline for children older than 8 years of age in 25-50 mg/kg daily given in 2-4 divided doses. Alternatively some clinicians recommended that children should receive 0.6-1.2 g/m2 daily.Tetracycline should be taken preferably one hour before or 2 hours after meals.Some specific indications along with some information on dosage is given below:Acne vulgaris: 250 mg four times daily or 500 mg 12 hourly for 1 week; 125-250 mg for several weeks or months. Duration of therapy is determined by individual progressAcute staphylococcal infections: 1-2 g daily in divided doses for 10-14 daysAcute streptococcal infections: 1-2 g daily in divided doses for 10 days. Prolonged therapy is needed to avoid risk of rheumatic fever or glomerulonephritisAmoebiasis: 1 g daily in four divided doses or 500 mg 12 hourly for 7 days. Given in association with amoebicidal agentsBrucellosis: 500 mg four times daily plus 1 g streptomycin twice daily for 1 week ; then 500 mg four times daily (no streptomycin) for 1 week. Prolonged therapy is necessary to avoid relapseSubacute bacterial endocarditis: 1-2 g daily in divided doses for 6 weeks. Usually given in combination with a bactericidal agentSyphilis: Total 30-40 g given in divided doses over 10-15 days. Serology and spinal fluid examination should follow the administration of tetracycline
Impaired absorption with antacids containing divalent and trivalent cations (e.g. Al, Ca, Mg), Fe, Zn and Na bicarbonate preparations, kaolin-pectin, bismuth subsalicylate, sucralfate, strontium ranelate, colestipol and colestyramine. May interfere with the bactericidal action of penicillin. May potentiate the effect of anticoagulants. May decrease efficacy of oral contraceptives. Nephrotoxic effects may be exacerbated by diuretics or other nephrotoxic drugs. May increase the hypoglycaemic effect of insulin and sulfonylureas in patients with DM. May increase toxic effects of ergot alkaloids and methotrexate.
Tetracycline Hydrochloride is contraindicated in patients hypersensitive to any of the member of tetracycline groups, since cross-sensitivity may occur Tetracycline Hydrochloride should be avoided in patients with systemic lupus erythematosus. Tetracycline Hydrochloride is considered to be contraindicated in renal impairment, particularly if severe ; if it must be given, doses should be reduced.
Teeth and bone: Tetclin can cause depression of bone growth, permanent graybrown discoloration of the teeth and enamel hypoplasia when given during tooth development (i.e. during the later half of pregnancy, during infancy and in childhood).Hypersensitivity reactions such as anaphylaxis, urticaria and rashes are uncommon. Photosensitivity reactions consisting of a red rash on areas exposed to intense sunlight can occur with Tetclin.Gastrointestinal effects: Epigastric distress and nausea are commonly seen after oral administration, and these symptoms are somewhat dose related. Vomiting can occur.Accentuated prerenal azotemia: Tetclin appears to aggravate pre-existing renal failure by inhibiting protein synthesis, which increases the azotemia from amino acid metabolism.Superinfections with oral and anogenital candidiasis are relatively common in patients taking Tetclin.Esophageal ulcerations: In most cases, the patients were taking the capsules with little or no fluid before going to bed. To help minimize this, oral doses should be given with adequate amounts of fluid.
Tetracycline should not be used during pregnancy because of the risk of hypertoxicity in the mother as well as the effects on the developing foetus. Use in pregnancy potentially during breast-feeding and in children up to the age of 8, or some authorise say 12 years, may result in impaired bone growth and permanent discoloration of the child's teeth.
Care should be taken if Tetclin is given to patients with impaired liver function and high doses should be avoided. Potentiality hepatotoxic drugs (including erythromycin, chloramphenicol, isoniazide and sulphonamides) should not be given concomitantly.
Tetracycline group of drugs
Store between 20-25° C.
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