Tetracyclines therapeutic effects

The most important evidence is probably offered by a recent double-blind, randomized trial which showed a better therapeutic effect of rifaximin in comparison to tetracycline in a cohort of SIBO syndrome patients [42] in particular, rifaximin administration produced a significant reduction of breath hydrogen levels in fasting conditions, peak of hydrogen excretion and cumulative breath hydrogen excretion after an oral dose of 50 g of glucose (fig. 1). Normalization of the test results was evident in 70% of the sample studied. 

Mechanism of Action A tetracycline antibacterial that inhibits bacterial protein synthesis by binding to ribosomal receptor sites also inhibits ADH-induced water reabsorption. Therapeutic Effect Bacteriostatic also produces water diuresis. Pharmacokinetics Food and dairy products interfere with absorption. Protein binding 41 %-91%. Metabolized in liver. Excreted in urine. Removed by hemodialysis. Half-life 10-15 hr. 

Mechanism of Action A tetracycline antibacterial that inhibits bacterial protein synthesis by binding to ribosomes. Therapeutic Effect Bacteriostatic. 

The antimicrobial drug, tetracycline, is found to be therapeutically effective when 250 mg of drug are present in the body. The t of tetracycline is 8 hours. What is the correct rate of infusion ... 

Pomserantsev, A.P., Shishkova, N.A., Marinin, L.I. (1992). Comparison of therapeutic effects of antibiotics of the tetracycline group in the treatment of anthrax caused by a strain inheriting tet- gene of plasmid pBC16. Antibiot. Khimioter. 37 31-4. (In Russian)... 

Tetracycline (chlortetracycline) and oxytetracycline These tetracyclines are incompletely absorbed from the gastrointestinal tract. Plasma concentrations fall with half-lives of 6-12 hours. They are predominantly excreted by the kidney, extrarenal elimination amounting at most to 10-20%. They have a lower affinity for fat and membranes, which means that higher dosages to achieve therapeutic effectiveness. However, higher dosages can contribute to an increased risk of systemic toxic effects and, as absorption from oral administration is incomplete, also to an increased risk of gastrointestinal adverse reactions. 

Deposition of tetracyclines in bone tissue has been demonstrated in animals (147) and man (148). However, whereas osseous tissue in adult patients treated with tetracycline has shown deposits only in areas of repair or remodeUing, children s bones contain extensive areas of deposition. Tetracycline deposition in bone has been reported to have an effect on longitudinal bone growth (149). In experimental tissue cultures, osteogenesis was impaired by tetracyclines in concentrations similar to serum concentrations that are associated with a therapeutic effect (that is 1 pg/ml) (150). The deposition of tetracyclines in human bone begins in utero as early as in the first trimester of pregnancy (148). With regular tissue turnover, the deposits disappear. 

The serum levels and therefore the therapeutic effectiveness of the tetracyclines can be markedly reduced or even abolished by antacids containing aluminium, bismuth, calcium or magnesium. Other antacids, such as sodium bicarbonate, may also reduce the bioavailability of some tetracyclines. Even intravenous doxycy-cline levels can be reduced by antacids. 

The calcium in food can complex with tetracycline to reduce its absorption. This is particularly notable with dairy products, which can reduce the absorption of the tetracyclines by up to 80%, thereby reducing or even abolishing their therapeutic effects. Doxyeyeline and minocycline are less affected by daily products (25 to 30% reduction). Orange juice and coffee do not interact with tetracycline. 

The absorption of both the tetracyclines and iron compounds is markedly reduced by concurrent use, leading to reduced serum levels of the tetracyclines. Their therapeutic effectiveness may be reduced or even abolished. 

A significant improvement of symptom severity and the absence of side effects was also evident after rifaximin administration but not after tetracycline, reinforcing, therefore, the validity of the therapeutic approach adopted. Rifaximin has proved to be effective in the treatment of gas-related symptoms in fact, in a recent paper, it was reported that a 7-day course of therapy significantly improved the severity of symptoms in a cohort of patients... 

Also, there are effective alternatives to antibiotics, such as vaccines, to prevent diseases. NRDC also advocated changing certain farm management practices, such as reducing the crowding of animals In feedlots, which should reduce stress and transmission of diseases. Both of those actions It was said should reduce the need for disease prevention. NRDC pointed out that It Is not advocating a ban of penclllln and the tetracyclines used at therapeutic levels to treat diseases. 

NRDC contended that the suspension of these subtherapeutlc uses of penicillin and the tetracyclines In animal feeds poses no human health problem. No potential human health problem has been Identified In the literature. Any risk of eating meat from an animal that becomes 111, because penicillin and the tetracyclines were not available, could be alleviated by using substitute antibiotics and better farming practices to prevent or reduce the Incidence of disease. Moreover, there would be an Increased probability of effectively treating the diseases with therapeutic levels of antibiotics If they were not used at subtherapeutlc levels. 

The committee recommended a comparison of subtherapeutic with therapeutic use of antibiotics on the prevalence of resistant transfer factors in meat animals. Also recommended was a study comparing the enteric flora of vegetarians and meat-eaters. A third study would involve workers in abattoirs and their contacts. These studies are in progress under the direction of Dr. Edward Kass at Harvard University and investigators at the Loma Linda Medical School. The committee also recommended further research on the mechanisms of the antibiotic growth effect. The report (7) said there is little indication that sale of antibiotics, including penicillin and tetracyclines, for feed and veterinary use, "has decreased as a result of the Swann Report."... 

Tetracyclines are a family of antibiotics which display a characteristic 4-fused-core ring structure (Figure 1.16). They exhibit broad antimicrobial activity and induce their effect by inhibiting protein synthesis in sensitive microorganisms. Chlortetracycline was the first member of this family to be discovered (in 1948). Penicillin G and streptomycin were the only antibiotics in use at that time, and chlortetracycline was the first antibiotic employed therapeutically that retained its antimicrobial properties upon oral administration. Since then, a number of additional tetracyclines have been discovered (all produced by various strains of Streptomyces), and a variety of semi-synthetic derivatives have also been prepared (Table 1.18). 

Before the introduction of specific vasopressin receptor antagonists, pharmacological treatments for hyponatremia centered on the use of loop diuretics and nonspecific inhibitors of vasopressin signaling, such as lithium carbonate and demeclocycline.11 The utility of such therapies has been limited by a range of sideeffects. Loop diuretic use can result in electrolyte imbalances and suffers from poor response predictability.11 Lithium carbonate suffers from a low therapeutic index and a risk of renal damage as well as limited effectiveness in many patients. Lithium carbonate has therefore been nearly completely supplanted by demeclocycline, a tetracycline antibiotic, in the treatment of chronic hyponatremia.12 Demeclocycline use is itself limited by its nephrotoxicity (particularly in cirrhotic patients), ability to cause reversible uremia, and ability to induce photosensitivity.1,11... 

TETRACYCLINES IRON-ORAL 1.1 iron levels when iron given orally 2.1 plasma concentrations of these drugs, with risk of therapeutic failure 1. 1 absorption 2. Iron chelates with tetracyclines and l their absorption 1. Separate doses as much as possible - monitor FBC closely 2. Separate doses of other drugs as much as possible and monitor their effect... 

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