Ampicillin elimination

In a crossover study healthy subjects were given either pivampicillin 350 mg every 8 hours or a tablet of MK-356 (approximately, pivampicillin 350 mg with probenecid 200 mg). Peak ampicillin levels of 4 to 5 micrograms/mL were found about 1 hour after administration ofthe first and last dose of both treatments suggesting that probenecid did not affect the ampicillin elimination. Administration of MK-356 (pivampicillin 700 mg with probenecid 4(X) mg) twice daily indicated that peak serum levels of ampicillin were increased and elimination rate slowed following successive doses. ... 

The importance of the penicillins as a class of heterocyclic compounds derives primarily from their effectiveness in the treatment of bacterial infections in mammals (especially humans). It has been estimated that, in 1980, the worldwide production of antibiotics was 25 000 tons and, of this, approximately 17 000 tons were penicillins (81MI51103). The Food and Drug Administration has estimated that, in 1979 in the U.S.A., 30.1 x 10 prescriptions of penicillin V and 44.3 x 10 prescriptions of ampicillin/amoxicillin were dispensed. This level of usage indicates that, compared to other methods of dealing with bacterial infection, the cost-benefit properties of penicillin therapy are particularly favorable. Stated differently, penicillin treatment leads to the elimination of the pathogen in a relatively high percentage of cases of bacterial infection at a relatively low cost to the patient in terms of toxic reactions and financial resources. 

Mass spectrometry coupled to liquid chromatography (LS/MS) eliminates the need for derivatization and, thus, circumvents one of the perturbing factors. Using an LS/MS method, Suwanrumpha and Freas [152] identified the above-mentioned metabolites of ampicillin (5.49 and 5.50) in human... 

Amoxycillin is a semisynthetic penicillin, a close congener of ampicillin and active against gram positive and negative organisms. Its absorption is more complete than ampicillin. Food does not interfere with its absorption. Its absorption after oral administration is complete hence less incidence of diarrhoea. It is eliminated in urine in unchanged form. 

In some cases, the same disease states exert no effect on drug pharmacokinetics as with amoxycillin and chloramphenicol in calves, and ampicillin and sulfamethazole in goats. Although feverish pigs show reduced elimination half-lives when oxytetracycline is given orally, there is no apparent effect after intravenous administration, which suggests an effect on gastrointestinal absorption (39). 

It has been recently reported (109) that use of both Penase and lactamase II hydrolysis and screening assays prior to chromatographic analysis can tentatively classify -lactams into three subgroups the first group includes a ceftiofur metabolite represented by desfuroyl-ceftiofur-cysteine the second, cephapirin and the third, penicillin G, ampicillin, amoxicillin, and cloxacillin. In this approach, portions of aqueous extracts of tissues are treated separately with Penase and lactamase II, and results are compared with those of untreated samples and positive controls. Bioactive ceftiofur metabolites are present, provided that the extracts retain inhibitory activity after Penase treatment but lose activity after lactamase II treatment and are positive in response to the immunochemical Lac-Tek-Cef test but negative to the Lac-Tek-Bl test (113). This approach can eliminate a large number of negative samples and, therefore, increases the efficiency of the assay. 

The result suggested that thioridazine was able to eliminate different antibiotic resistances singly or jointly in Escherichia coli strains and Shigella flexneri 6 BDC1 quite efficiently, but had a much weaker effect on Vibrio cholerae (Table 42). The pattern of elimination further indicated that penicillin, ampicillin, and amoxicillin were determined by a single plasmid in these bacteria. It seems that effective elimination depended on the curing concentrations, which were close to the MIC value of thioridazine for any... 

When cells are transformed with naked vector DNA (as opposed to packaged, protein associated DNA in viruses) only a fraction of the cells, 10% under the best conditions, take up the DNA. Therefore, the cells receiving the DNA or the Transformants have to be isolated from among the non-receiving Tmtransformed cells. This is accomplished by using the selectable property encoded by the vector, such as resistance to antibiotics (ampicillin, tetracycline, etc.). Exposure of the mixed population of transformed and untransformed cells to the antibiotic results in the elimination of untransformed cells. Transformed bacterial cells can be isolated, grown, and vector DNA prepared from them for introduction into the expression host cell of choice. 

These are adapted from the ampicillin molecule, with a side-chain derived from urea. Their major advantages over the carboxypenicillins are higher efficacy against Pseudomonas aeruginosa and the fact that as monosodium salts they deliver on average about 2 mmol of sodium per gram of antimicrobial (see above) and are thus safer where sodium overload should particularly be avoided. They are degraded by many p-lactamases. Ureidopenicillins must be administered parenterally and are eliminated mainly in the urine. Accumulation in patients with poor renal function is less than with other penicillins as 25% is excreted in the bile. An unusual feature of their kinetics is that, as the dose is increased, the plasma concentration rises disproportionately, i.e. they exhibit saturation (zero-order) kinetics. 

The optimum pH for the analysis was found to be 4. Similar systems were found to be useful for eliminating the interference of such drugs as ampicillin, methicillin, etc. (mentioned above)104 140 191. 

There are numerous natural substances that have useful therapeutic properties as well as other undesirable properties. From these starting points, medicinal chemists have improved on nature. For example, while extremely useful in the treatment of infection, penicillin is not available by the oral route this shortcoming is overcome in the analogue ampicillin (Figure 8.3A). Similarly, the obvious deleterious effects of cocaine have been eliminated in the local anesthetic procaine (Figure 8.3B). The short activity and weak steroid progesterone is converted to a stronger... 

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