Treatment of urinary tract infection with norfloxacin. Analysis of cost

Review of Properties and Analytical Methods for the Determination of Norfloxacin

The first-generation quinolones have their greatest potency against Gram-negative bacteria, but newly developed molecules have exhibited increased potency against Gram-positive bacteria, and existing agents are available with additional activity against anaerobic microorganisms. Norfloxacin is a broad-spectrum antimicrobial fluoroquinolone used against Gram-positive and Gram-negative organisms (aerobic organisms). There are different analytical methods available to determine norfloxacin applied in quality control of this medicine in order to ensure its effectiveness and safety. The authors present an overview of the fourth generation of quinolones, followed by the properties, applications, and analytical methods of norfloxacin. These results show several existing analytical techniques that are flexible and broad-based methods of analysis in different matrices. This article focuses on bionalytical and pharmaceutical quality-control applications, such as thin-layer chromatography, microbiological assay, spectrophotometry, capillary electrophoresis (CE), and high-performance liquid chromatography (HPLC).

Environmental metabolites of fluoroquinolones: synthesis, fractionation and toxicological assessment of some biologically active metabolites of ciprofloxacin

BACKGROUND, AIM, AND SCOPE

Biowastes produced by humans and animals are routinely disposed of on land, and concern is now growing that such practices provide a pathway for fluoroquinolone (FQs) antibacterial agents and their environmental metabolites (FQEMs) to contaminate the terrestrial environment. The focus of concern is that FQs and FQEMs may accumulate in amended soils to then adversely impact on the terrestrial environment. One postulated impact is the development of a selective environment in which FQ-resistant bacteria may grow. To find evidence in support of an accumulation of antibacterial-like activity, it was first necessary to establish whether any biologically active FQEMs could be synthesized by physicochemical factors that are normally present in the environment. However, many FQEMs are not commercially available to be used as standards in such studies. FQEMs were therefore synthesized using well-defined processes. They were subsequently analyzed using spectroscopy (UV-vis) and high performance liquid chromatography with mass spectral detection. The antibacterial-like activities of fractionated FQEMs were then assessed in novel bacterial growth inhibition bioassays, and results were compared to those obtained from instrumental analyses.

MATERIALS AND METHODS

Parent FQs were either exposed to sunlight or were synthesized using defined aerobic microbial (Mycobacterium gilvum or a mixed culture derived from an agricultural soil) fermentation processes. Mixtures of FQEMs derived from photo- and (intracellular) microbial processes were isolated by preparative chromatography and centrifugation techniques, respectively. Mixtures were subsequently fractionated using analytical high-performance thin layer chromatography (HPTLC), and excised analytes were tested in bioautography assays for their antibacterial-like activities. Two bacteria, Escherichia coli (E. coli) and Azospirillum brasilense (A. brasilense) were used as reporter organisms in testing FQ standards and any subtle differences between biologically active FQEMs of ciprofloxacin (CF).

RESULTS AND DISCUSSION

FQEMs produced in the photo-synthetic process had UV-vis profiles that were indistinguishable from the parent FQs, and yet mass spectral data revealed the presence of N-formylciprofloxacin (FCF). In contrast, the UV-vis profiles of FQEMs synthesized by M. gilvum and a mixed culture of microorganisms had UV-vis profiles that were similar to one another and markedly different to the parent fluoroquinolones. Mass spectral studies confirmed the presence of FCF and N-acetylciprofloxacin in both microbial ferments. In addition, a photo-FQEM (Cp 6), three M. gilvum FQEMs (Cm 5, Cm 8, and Cm 10) and a mixed culture FQEM (Cs 6) of CF and many other FQEMs of CF, norfloxacin (NF), and enrofloxacin (EF) were fractionated using HPTLC, although their identities have yet to be confirmed. Differences between bioautography results were obtained when E. coli or A. brasilense were used as reporter organisms. Parent FQs (CF and EF) and the FQEMs of CF (Cp 6, Cm 8, and Cs 6) displayed antibacterial-like activity when using E. coli as the reporter organism. In contrast, A. brasilense was insensitive to parent CF and sensitive to EF and all tested FQEMs of CF. Results are consistent with photo- and microbial processes modifying CF in different ways, with the latter changing the UV-vis chromophores. It can be inferred that a lack of detection of analytes (especially photo-FQEMs) when using UV-vis does not necessarily indicate an absence of analyte. Additionally, similarities between the UV-vis profiles of FQEMs extracted from the (monoculture) M. gilvum and the mixed culture microbial aerobic ferments are consistent with similar processes operating in both ferments. Results of HPTLC and bioautography studies revealed that mixtures of (photo- and microbial) FQEMs could be fractionated into individual components.

CONCLUSIONS

Bioactive FQEMs of ciprofloxacin, as a representative FQ, can be synthesized by photo- and microbial processes, and their detection required the use of both instrumental and bioautography analytical techniques. It is likely that such FQEMs will also be present on agricultural land that has been repeatedly amended with FQ-contaminated biosolids.

RECOMMENDATIONS AND PERSPECTIVES

The use of instrumental analytical techniques alone and especially photometric detection techniques will underestimate antibacterial-like activities of FQEMs. Moreover, the extraction technique(s) and the selected toxicological endpoint(s) require careful consideration when assessing bioactivity. It is therefore recommended that instrumental analytical techniques and several bioautography assays be performed concurrently, and bioautography assays should use a variety of reporter organisms. Two types of bacterial growth bioassays are recommended in any assessment of antibacterial-like activity derived from CF (and possibly from other FQs). A standardized E. coli bioassay should be used as a general screening procedure to facilitate intra- and inter-laboratory exchange of data. Additionally, soil-specific (region-specific) growth inhibition bioassays should be undertaken using several species of endemic soil bacteria. It is likely that the two sets of data will be useful in future risk assessment processes.

All dysuria is local. A cost-effectiveness model for designing site-specific management algorithms

OBJECTIVE

To determine the cost-effectiveness of management strategies for dysuria in different office settings.

DESIGN

Decision and cost-effectiveness analyses, assuming the payer's perspective. Data on disease prevalence, test characteristics, treatment efficacy, and adverse effects were drawn from the English language literature using medline searches and bibliographies.

SETTING

Hypothetical primary care practice.

PATIENTS

Otherwise healthy, nonpregnant women with symptoms of dysuria, urgency, and frequency.

INTERVENTIONS

All reasonable combinations of urinalysis, urine culture, pelvic examination, chlamydia and gonorrhea cultures, and empiric treatment with trimethoprim-sulfamethoxazole.

RESULTS

The cost-effectiveness of strategies varied substantially among different patient settings. In all settings, empiric trimethoprim-sulfamethoxazole for all patients was least expensive and least effective. Most testing increased both cost and effectiveness. Compared to empiric antibiotics, performing pelvic examination and urine culture for women with normal urinalyses had a marginal cost-effectiveness ratio of $4 to $32 per symptom-day avoided (SDA). Adding urine culture for patients with pyuria had a marginal cost of $34 to $107 per SDA, which fell to $40/SDA when the prevalence of resistance to trimethoprim-sulfamethoxazole exceeded 40%. Pelvic examination and urine culture for all patients regardless of urinalysis results achieved the greatest benefit but at the highest cost (>$300 per SDA).

CONCLUSIONS

In otherwise healthy women with symptoms of dysuria and no vaginal complaints, performing pelvic exam and urine culture based on urinalysis offers a reasonable alternative to empiric therapy. Other testing may be warranted, depending on antibiotic resistance and the value of avoiding a day of dysuria.

Urinary tract infection: economic considerations

Urinary tract infection results in significant morbidity and mortality while consuming large amounts of national resources. The prevention, diagnosis, and treatment of urinary tract infection produce both costs and benefits, and economic analysis provides a rational framework for looking at these effects. The goals and methods of economic analysis in medicine are summarized, and strategies to address uncomplicated cystitis, nosocomial urinary tract infection, and pyelonephritis are reviewed, with an emphasis on the economic trade-offs faced by decision makers.

Pharmacokinetic determination of relative potency of quinolone inhibition of caffeine disposition

Quinolone is reported to interact with caffeine, often resulting in an increase both in the plasma half-life and AUC, a decrease in total plasma clearance, and little change in the absorption rate constant and maximum plasma level. These complex changes in the pharmacokinetics of caffeine were analyzed experimentally and from published reports in order to determine the nature of the interaction, which is thought to be due to inhibition of caffeine metabolism by quinolones. A simple pharmacokinetic model for the caffeine-quinolone interaction was developed, which provides a unified method for evaluation and comparison of the effect of quinolones on the disposition of caffeine. The model is applicable to other methylxanthines, such as theophylline. The relative potency of the interactions of quinolones with caffeine in humans has been established as enoxacin (100), pipemidic acid (29), ciprofloxacin (11), norfloxacin (9) and ofloxacin (0).

Quinolone antimicrobial agents: adverse effects and bacterial resistance

Adverse effects, drug-drug interactions and bacterial resistance to the new quinolone antimicrobial agents are reviewed. Clinical adverse effects are reported to occur in 5-10% of patients, and include primarily gastrointestinal disturbances, central nervous system toxicity and rash. Laboratory abnormalities are reported to occur in 5-12% of patients, and include mild reversible elevations of transaminases. Quinolones are not recommended in persons whose bone growth is incomplete or in pregnant or nursing women because cartilage toxicity has been observed in juvenile beagles. Drug-drug interactions may occur between quinolones and theophylline, caffeine, and magnesium- or aluminium-containing compounds such as antacids and sucralfate. Bacterial resistance occurs by chromosomal mutations which alter the target enzyme DNA gyrase or decrease drug accumulation. Emergence of resistance during therapy is uncommon to date but can be problematic in infections with Pseudomonas aeruginosa. Staphylococcus aureus and other bacteria for which the therapeutic index may be low. In summary, quinolones thus far have been well tolerated, but more experience is needed to determine the exact nature and extent of adverse effects and emergence of bacterial resistance.