Candidaurinary tract infections: treatment options

Candiduria is a nonspecific finding that occurs with contamination of a urine sample, colonization of an indwelling catheter and/or the bladder, symptomatic cystitis and invasive upper tract infection. Most patients are colonized and do not require antifungal therapy. Removing predisposing factors, such as indwelling catheters and antibiotics, will clear candiduria in almost 50% of asymptomatic patients. For patients with symptomatic Candida urinary tract infections, a variety of treatment options are available. Fluconazole is the antifungal agent of choice, achieving high urine concentrations with the oral formulation. Rarely, amphotericin B or flucytosine are used. Newer azole agents and echinocandins are not recommended for the treatment of urinary tract infections since they fail to achieve adequate urine concentrations.

The sensitivities to first-line antibiotic therapy of the common urinary tract bacterial infections detected in urine samples at a hospital in metropolitan Kampala (Uganda)

BACKGROUND

Urinary tract infections (UTIs) are among the most common human infections. Many urinary tract bacteria are capable of expressing drug resistance. Resistant bacteria may be present from the commencement of the infection or may develop during treatment. This study focused on the problem of antibiotic resistance to the first-line drugs that were used to treat patients presenting with urinary tract infections at Rubaga hospital in Kampala, Uganda.

OBJECTIVES

The objective of this study was to isolate and identify the major bacterial pathogens of symptomatic and asymptomatic UTIs among patients at Rubaga hospital. Furthermore, the study sought to determine the antimicrobial susceptibility patterns of the major bacterial isolates to the first-line drugs used to treat UTIs at Rubaga hospital.

METHODS

Urine samples were aseptically collected and examined microscopically and were microbiologically cultured on blood agar, nutrient agar and on MacConkey agar. The isolates obtained were then identified using standard tests and tested for antimicrobial sensitivity by the Kirby-Bauer technique.

RESULTS

The isolated pathogens included Escherichia coli (10.9%), Staphylococcus (31.9%), Streptococcus (9.2%), Klebsiella species (21.0%) and Proteus species (10.1%). 20 (16.8%) of the isolates were lactose fermenting gram-negative rods that were also indole-negative. These isolates were termed 'unclassified coliforms' in this study but were probably Enterobacter species. On antimicrobial susceptibility testing, all the gram-negative isolates were significantly resistant to amoxycillin, cotrimoxazole, erythromycin, and to nalidixic acid; but were susceptible to nitrofurantoin. Among the gram-negative isolates, only Klebsiella species were significantly resistant (p<0.05) to ciprofloxacin. The gram-positive cocci were susceptible to amoxycillin, ciprofloxacin, and to erythromycin but resistant to cotrimoxazole and nalidixic acid. Unlike the Staphylococcus species that were significantly resistant to nitrofurantoin, Streptococcus species were moderately susceptible to the drug.

CONCLUSION

The common urinary tract bacteria detected in Rubaga hospital in Uganda were most sensitive to Ciprofloxacin and Nitrofurantoin.

Determination of Methylene Blue and Leucomethylene Blue in Male and Female Fischer 344 Rat Urine and B6C3F1 Mouse Urine

A liquid chromatographic method for the determination of methylene blue and leucomethylene blue in male and female Fischer 344 rat urine and male and female B6C3F1 mouse urine was developed for use in supporting toxicokinetic studies, validated, and used to analyze urine samples for a preliminary dose level range-finding study. The method was validated for a concentration range of 10.0 to 20,000 ng/mL in urine. Samples up to 75,000 ng/mL demonstrated good recoveries when diluted into the range of the calibration curve. Six sets of calibration standards were prepared in F344 male rat urine for analysis to demonstrate reproducibility and ruggedness. The stability of sample extracts was determined under various storage conditions. During the course of analyses of the animal samples, a possible metabolic process was observed. Although Azure B is a significant impurity in methylene blue trihydrate, the amount of Azure B seen in urine samples collected from rodents dosed with methylene blue trihydrate is significantly greater than the amount seen in rodent urine spiked directly with methylene blue. This observation suggests possible N-demethylation of the methylene blue as a metabolic transformation to Azure B.

Exposure assessment for study of olfactory function in workers exposed to styrene in the reinforced-plastics industry

BACKGROUND

This study was undertaken in conjunction with an evaluation of the olfactory function of 52 persons exposed to styrene vapors to provide quantitative styrene exposure histories of each subject for use in the interpretation of the results of olfactory function testing.

METHODS

Current and historic exposures were investigated. Historic exposures were reconstructed from employment records and measurements of styrene exposure made in the subject facilities over the last 15 years. Current exposures were estimated for every exposed subject though personal air sampling and through pre- and post-shift measurements of urinary metabolites of styrene.

RESULTS

The study population had been employed in the reinforced-plastics industry for an average of 12.2 +/- 7.4 years. Their mean 8-hr time weighted average (TWA) respirator-corrected annual average styrene exposure was 12.6 +/- 10.4 ppm; mean cumulative exposure was 156 +/- 80 ppm-years. The current respirator-corrected 8-hr TWA average exposure was 15.1 +/- 12.0 ppm. The mean post-shift urinary mandelic and phenylglyoxylic acid (PGA) concentrations were 580 +/- 1,300 and 170 +/- 360 mg/g creatinine, respectively and were highly correlated with air concentrations of styrene.

CONCLUSIONS

This quantitative exposure evaluation has provided a well-characterized population, with documented exposure histories stable over time and in the range suitable for the purposes of the associated study of olfactory function.

[Study on the direct determination of lomefloxacin in urine by derivative-synchronous fluorescence]

The LMX fluorescence properties at various pH of media were studied. The experiments indicated that LMX fluorescence emission wavelength is red shifted 40 nm at pH value of 3.3. The background interference was eliminated effectively. Under this condition, a new method for the determination of lomefloxacin in human urine by derivative-synchronous fluorescence has been developed. The linear equation of LMX can be obtained as dF/d lambda = -6.642c-24.143, of which the correlation coefficient is 0.9996. When concentrations of LMX were within the range of 0.35-28.10 mg.L-1, there exists a good linear relationship between the concentration and fluorescence intensity of LMX. The detection limit was 0.35 mg.L-1. The average recoveries of LMX were 97%-104% and the RSD were 0.83%-1.62%.

Differential-pulse adsorptive stripping voltammetric determination of the antibacterial lomefloxacin

A differential-pulse adsorptive stripping voltammetric method for the determination of trace amounts of the antibacterial lomefloxacin is proposed. By using an accumulation potential of -0.30 V and a 2 min accumulation time, the linear concentration range of application was 1.0-10.0 ng ml(-1) of lomefloxacin, with a relative standard deviation of 3.8% (for a level of 5.0 ng ml(-1)) and a detection limit of 0.3 ng ml(-1). The method was applied to determination of lomefloxacin in human urine and serum samples. It was validated using HPLC as a reference method. Recovery levels of the method reached 100% in all cases.

On-column amperometric detection of ofloxacin and pasiniazid in urine by capillary electrophoresis with an improved fractured joint and small detection cell

An improved high-voltage electric field isolating joint and small detection cell have been carefully designed and fabricated. The joint possesses short steady time, high electric conductance efficiency and high performance. The cell is convenient to install and remove the capillaries with and without the joint, as well as to fix, adjust and insert the microelectrode into the detection capillary. Using the joint and the cell, an analytical method for determination of ofloxacin (Oflx) and pasiniazid (Ipa) in urine by capillary electrophoresis with on-column amperometric detection was developed. The calibration lines were linear in the range of 10-100 mg l-1 of Oflx and 1.0-50 mg l-1 of Ipa, respectively. The detection limits were 8.5 mg l-1 of Oflx and 0.80 mg l-1 of Ipa. Their recovery ranged from 101 to 104%. The accuracy and intra-day and inter-day reproducibility of Oflx and Ipa were determined with satisfactory results. This method was successfully used for determining Oflx and Ipa in human urine.

[Antibacterial activity of urine after administration of ofloxacin for 5 days]

The antibacterial activity of ofloxacin was evaluated in urine over a period of 96 h after oral administration for 5 days of 200 mg twice a day in 12 healthy female volunteers. Bacteriostatic and bactericidal activity of urines were studied for five strains of enterobacterias recovered from urinary infections: two strains of Escherichia Coli Nal-S and Nal-R, two strains of Proteus mirabilis Nal-S and Nal-R, and one strain of Klebsiella pneumoniae Nal-S. Mean urinary concentrations of ofloxacin were very high during the first 12 h following last intake. They were still above 7 mg/l till the 48th hour and above 1.6 mg/l till the 72nd hour. Bactericidal activity of urine was present for 72 h in respect of four strains studied at that time; urine was not bactericidal as regards E. coli Nal-R. After 5 days of oral treatment with ofloxacin (200 mg b.i.d.), urine retains a bactericidal activity for at least 72 h against bacterial strains of urinary tract infections.

A new in vitro/in vivo kinetic correlation method for nitrofurantoin matrix tablet formulations

The kinetic distributions of in vitro percentage release and in vivo percentage urinary excretion rates of nitrofurantoin from matrix tablets were plotted using a kinetic program. In vitro release rates were determined using the USP paddle and half-change methods. Urinary excretion curves of the drug were characterized by means of the statistical moments. The individual linear correlations between each in vitro and in vivo kinetic distribution were established, and regression equations were calculated. The application results of the best correlations obtained were evaluated according to in vivo results. A reversed kinetic procedure was applied for transformation of the correlated kinetic values to the drug percentage release rates. The modified Langenbucher kinetic showed excellent linear correlation (r = .9985). The method that is proposed in this study, the kinetic correlation program, is simple, independent of time, and suggests that it is possible to use kinetic distributions in the in vitro/in vivo correlation. This study also suggests using kinetic correlation to investigate the suitability of the in vitro dissolution methods with the in vivo drug dissolution.

The influence of ofloxacin (Tarivid) on the parasite-host inter-relationship in patients with chronic urinary tract infection

In urinary tract infection (UTI), the aim of antimicrobial chemotherapy is either to attenuate the virulence of infective micro-organisms, to influence the interaction between germs and host or to kill bacteria. In 25 females (aged 49.8+/-14.7 years) with chronic UTI, parameters of inflammation (CRP, alpha 2-globulin, leukocytes, ESR) as well as renal function were analyzed under the treatment with ofloxacin 2 x 200 mg. Subsequently, bacterial attachment, bacterial count, leukocytes, antibody-coated bacteria (ACB), immunoglobulin (Ig) G, albumin, a2-microglobulin, Tamm Horsfall protein, secretory IgA (sIgA) and lysozyme were determined in urine. The micro-organisms were examined with regard to the expression of hemolysin, aerobactin, P-fimbriae and according to their plasmid profile. Ofloxacin serum levels were analyzed once prior to, on day 6 during and on day 3 after drug administration. In all cases, the acute clinical symptoms had disappeared after 10 days of treatment, all bacteria were eliminated, and the parameters of inflammation in serum and urine had returned to normal. On the sixth day of therapy, no expression of P-fimbriae was detectable in the Escherichia coli strains isolated, and the attachment rate decreased from 42+/-30.9% to 11.1+/-18.1%. The sIgA level rose from 42.6+68.5 prior to therapy to 88.8+/-136.8 mmol/l on day 3 after therapy; acute symptoms of UTI did not recur in any case during the period of 1 year.

Urinary pharmacodynamics of low-dose ciprofloxacin and ofloxacin

The incidence of resistant uropathogens to the fluoroquinolones is increasing, but their effectiveness in the urine against these strains is unknown. In this investigation, we studied the urinary pharmacodynamics of ciprofloxacin (100 mg) and ofloxacin (200 mg) against urinary isolates that were moderately resistant to ciprofloxacin (Escherichia coli, MIC = 4; Klebsiella pneumoniae, MIC = 4. Staphylococcus saprophyticus, MIC = 8) and ofloxacin. Seven healthy female volunteers received three doses (one dose every 12 h) of ciprofloxacin and ofloxacin in a randomized, crossover design with a 1-week washout period between regimens. Urine bactericidal activity was determined after the first and third dose of each drug. Both ciprofloxacin and ofloxacin exhibited prolonged (> or = 6 h) urine bactericidal activity against the E. coli and K. pneumoniae isolates after the first dose. No bactericidal activity was demonstrated for ciprofloxacin against the S. saprophyticus strain. In contrast, ofloxacin exhibited urine bactericidal activity for 8 h against this isolate. Similar findings were observed after the third dose, with the exception that ciprofloxacin exhibited a short period (4 h) of bactericidal activity against the S. saprophyticus strain. In summary, low-dose regimens of ciprofloxacin and ofloxacin exhibited prolonged bactericidal activity against moderately resistant strains of common bacterial uropathogens. Only ofloxacin demonstrated bactericidal activity in the urine during the first dosing interval against a moderately resistant isolate of S. saprophyticus.

Detection of fluoroquinolones in urinary specimens from patients undergoing anti-tuberculous therapy

A paper strip impregnated with ferric chloride has been developed for visual detection of fluoroquinolones in urine based on a change of colour due to the chelation of the transition metal ion to the beta-oxo acid array in the 4-oxo-1,4-dihydropyridine-3-carboxylic acid moiety of the fluoroquinolone molecule. In urine specimens, the detection limit of the strip was 100 mg/l for pefloxacin, 200 mg/l for ciprofloxacin, fleroxacin, levofloxacin, norfloxacin, ofloxacin and sparfloxacin, and 300 mg/l for trovafloxacin. In 193 urine specimens taken from 138 patients on ofloxacin therapy and 55 controls preliminary evaluation of the strip showed that all the 55 specimens from control patients were negative, while 112 out of the 138 ofloxacin-treated patients were positive. Quantitative analysis by high-performance liquid chromatography of the 26 strip-test-negative specimens taken from patients with ofloxacin treatment indicated that these urinary specimens contained less than 200 mg/l of the antimicrobial, mostly because of poor renal function and in some occasions, non-compliance. This strip method would provide a convenient way of monitoring drug compliance in patients who receive fluoroquinolone therapy for tuberculosis.

[Disorders of kidney function in patients with benign prostatic hyperplasia]

The examination of 648 males aged 50 to 86 to conduct an early outpatient detection of renal dysfunction in the elderly men employed an original technique of renal function assessment based on the kinetics of urinary 5-NOK elimination. Renal dysfunctions were revealed in 165 patients, in 159 of them the underlying cause was benign prostatic hyperplasia. The results were compared with those obtained at radionuclide tracing and Reberg-Tareev test. The correlation found indicated the authors' technique informative value and its compatibility with the above methods. Identification of renal dysfunction at early stages of benign prostatic hyperplasia allowed their timely hospitalization and operative treatment which enables the physicians to prevent progression of chronic renal failure in these patients.

Urine bactericidal activity of pefloxacin versus norfloxacin in healthy female volunteers after a single 800-mg oral dose

In an open randomised crossover study the antibacterial activity of pefloxacin and norfloxacin was assessed in the urine after a single 800-mg oral dose in 14 healthy female volunteers. Pefloxacin demonstrated lower peak concentrations in the urine than norfloxacin (mean, 217.2 mg/l versus 492.9 mg/l as determined by the microbiological assay) but pefloxacin was present over a longer period of time in sufficient concentrations than norfloxacin. Mean urine levels of at least 2 mg/l were present for 7 days after pefloxacin administration and 2 days after norfloxacin administration as determined by the microbiological assay. Overall, the urinary recovery of pefloxacin and norfloxacin amounted to 49.3% and 25.1%, respectively, of the total administered dose. The average urine bactericidal activity against the five test organisms was as follows: against reference strain Escherichia coli ATCC 25922 susceptible to nalidixic acid (Nal-S) for 5 days with pefloxacin and 2 days with norfloxacin; against three clinical isolates, one strain each of E. coli resistant to nalidixic acid (Nal-R), Klebsiella pneumoniae Nal-R, and Staphylococcus saprophyticus, for 3 days with pefloxacin and 24 h with norfloxacin; and against a clinical isolate of Enterococcus faecalis for 2 days with pefloxacin and 12 h with norfloxacin. In conclusion, pefloxacin as a single dose proved to have sufficiently high and long-lasting urine bactericidal activity against urinary pathogens. These findings support the results of a meta-analysis of seven clinical trials in patients with uncomplicated lower UTI, demonstrating a single oral dose of 800 mg pefloxacin to be as effective as a conventional treatment with comparative drugs.

Capillary electrophoresis and supercritical chromatography, complementary and alternative techniques for the determination of urinary metabolites of styrene

Two analytical methods without an extraction step were developed using capillary electrophoresis and supercritical fluid chromatography in order to determine phenylglyoxylic (PGA) and mandelic (MA) acids in urine, with minimum treatment and manipulation of biological samples. The urine was diluted ten-fold in acetonitrile and directly injected into the analytical systems after centrifugation. Analysis was performed by capillary electrophoresis on alkyl bonded phase capillary columns with sodium formiate (4 x 10(-2) M)-isopropanol (9:1, v/v) as a buffer, and by supercritical fluid chromatography on a Diol bonded phase silica column with ethanol-water-methanesulphonic acid (97.5:2.4:0.1, v/v) as coeluent of CO2. Detection of PGA and MA was performed by ultraviolet detection at 255 and 210 nm, respectively. The methods are in agreement, and are easily able to detect 5 mg/g creatinine for PGA, and 15 mg/g creatinine for MA, which are one twentieth of the lowest biological exposure index values.

Sensitive determination of nitrofurantoin in human plasma and urine by high-performance liquid chromatography

A highly sensitive and selective HPLC method was developed and validated for the determination of nitrofurantoin in human plasma and urine. The method involves the liquid-liquid extraction of drug and internal standard from plasma with ethyl acetate followed by evaporation and reconstitution in mobile phase. Urine samples were simply diluted with purified water. UV detection was done at 370 nm. The limit of quantification for nitrofurantoin in plasma was 0.010 micrograms/ml. In urine nitrofurantoin could be quantified down to 0.380 microgram/ml. Linearity was proven over the whole calibration range in plasma (2.48-0.0100 microgram/ml) as well as in urine (187 micrograms/ml-0.380 microgram/ml). The method was validated according to Good Laboratory Practice guidelines and its suitability was demonstrated by analysis of samples from a pharmacokinetic study.

Penetration of pefloxacin and its desmethyl metabolite into the uroepithelium after a 800-mg single oral dose in human patients

Penetration of pefloxacin into the uroepithelium was studied in 20 patients (10 men and 10 women) receiving a single oral dose of 800 mg. Samples of serum, urine, and uroepithelium were taken 1.8 h (mean) after the dose. Pefloxacin and its active metabolite, norfloxacin, were assayed by liquid chromatography, and the microbiologically active compounds were quantified by a microbiological assay. Both procedures were correlated (r > 0.7); nevertheless, slight differences detected in concentrations depended on the levels of norfloxacin achieved in the biological samples. The serum and tissue concentrations were higher than the concentration of bactericide (4 micrograms.ml-1), except in one case. The uroepithelium concentration of pefloxacin was proportional to the serum concentration (r = 0.79). The urinary concentrations ranged from 1.2 micrograms.ml-1 to 82.4 micrograms.ml-1. The mean norfloxacin/pefloxacin ratios were 3% in serum, 8% in uroepithelium, and 44% in urine. The mean uroepithelium/serum concentration ratios were 1 for pefloxacin and 2.3 for norfloxacin. This result shows that, at a time close to that of the maximum concentration, there is good penetration of pefloxacin and norfloxacin into the uroepithelium.

In vivo/in vitro correlations of nitrofurantoin matrix tablet formulations

In our recent study, a new sustained release dosage form of nitrofurantoin (nft) as matrix tablets by 2(2) factorial design has been prepared by using different drug:polymer ratios. The effect of the polyvinylpyrolidone contents of nft matrix tablets on dissolution rate and bioavailability of the drug have been evaluated. The ideal formulation which fitted at USP XXII dissolution norms was tested by in vivo experiments. The satisfactory correlation was also obtained between the in vivo and the in vitro results. This study suggested that the amounts of nft excreted in urine can be calculated by using in vitro dissolution results and sampling time.

Antibiotic activity in microbiological media versus that in human urine: comparison of ampicillin, ciprofloxacin, and trimethoprim-sulfamethoxazole

The activities of three antibiotics in both Mueller-Hinton broth (MHB) and pooled human urine were compared by using an in vitro pharmacodynamic model. Clinical and reference strains of Escherichia coli were exposed to antibiotics at concentrations achievable in human urine. The rate of bacterial killing (time to a reduction of 3 log10 CFU/ml) and the extent of bacterial killing at 24 h were examined. Between MHB and urine, there were no significant differences in the rate or extent of bacterial killing for both ampicillin and ciprofloxacin. For trimethoprim-sulfamethoxazole there was no significant difference in the extent of bacterial killing in urine compared with that in MHB (P > 0.1); however, there was a significant decrease in the rate of bacterial killing in urine compared with that in MHB (P < 0.001). We conclude that with ampicillin and ciprofloxacin, activity against E. coli in MHB is predictive of the effects in human urine. The activity of trimethoprim-sulfamethoxazole in MHB predicts the extent but not the rate of bacterial killing in human urine.

Effect of urine pH and ascorbic acid on the rate of conversion of methenamine to formaldehyde

The kinetics of conversion of methenamine to the active form formaldehyde were studied in pooled urine samples at 37 degrees in the pH range 4.9-6.5. Using a method for the determination of both formaldehyde and unhydrolyzed methenamine, the rate of formaldehyde formation in urine was found to be apparent first order and was pH dependent. Bactericidal concentrations of formaldehyde (> 28 micrograms ml-1) were achieved in 3 h in urine of pH 6.0 containing methenamine at 750 micrograms ml-1. There was no difference in the in vitro rate of conversion of methenamine to formaldehyde between the urine collected from normal subjects and the urine from subjects administered ascorbic acid. The rates of degradation of the mandelate and hippurate salts in buffer systems of various pH values did not differ significantly from those of methenamine base in urine adjusted to the same pH. The half-life of methenamine conversion to formaldehyde increased approximately 20 times from 20 h at pH 5.0 to about 400 h at pH 6.5. The data suggest that unless the urine is maintained below pH 6 only a small fraction of methenamine would be converted daily to formaldehyde and, thus, may explain the need for large doses of this drug in patients.

[A clinical study on postantibiotic effect (PAE) and its application to chemotherapy for complicated cystitis with an automatic simulator of urinary drug concentration]

In an in vitro complicated cystitis model, the concentrations of the urinary antimicrobial agents were determined using a computer-controlled automatic urine concentration simulator. The effects on the bacterial count curves showing the presence or absence of PAE in antimicrobial agents were studied by comparing the times required for regrowth to the concentration at the initial inoculation, i.e., effective regrowth time (ERT). The following results were obtained. 1. When beta-lactam antimicrobial agents (such as AMPC and CFIX) with no PAE against the gram-negative rods were tested, the ERT of the gram-negative rods were about two hours shorter than that of the gram-positive coccus. 2. When new quinolone antimicrobial agents (such as OFLX) and aminoglycosides (such as ISP) that possess PAE against both the gram-positive and negative organisms were used there was no difference between ERT of the gram-negative rods and gram-positive coccus. Therefore, it was demonstrated that the presence or absence of PAE is also reflected in the cell number curve in the case of this in vitro model, more closely related to clinical cases, when the antibiotics is simulated in urinary concentration shifting.

Determination of cefixime and its metabolites by high-performance capillary electrophoresis

Cefixime (CX), an oral cephalosporin antibiotic, and its metabolites in human digestive organs were separated by various modes of high-performance capillary electrophoresis. The zone electrophoresis mode in phosphate buffer (pH 6.8) containing 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulphonate gave the best separation, permitting the complete resolution of CX and all of five metabolites. On the other hand, the plain zone electrophoresis mode in phosphate buffer (pH 6.8) offered a simple procedure for the direct determination of urinary CX concentration using intact urine samples.

Relationship between renal function and disposition of oral cefixime

The pharmacokinetics of cefixime following a single oral dose of 200 mg have been investigated in 6 normal subjects and in 22 patients with various degrees of renal insufficiency. Serum and urine samples were collected between 0 and 72 h and were subjected to two methods of analysis: bioassay and HPLC. There was a linear relationship between the two sets of results from 228 samples. This result suggests that none of the metabolites, which may accumulate in uraemic patients, has antibacterial activity. In normal subjects, the peak serum level (Cmax) was 2.50 micrograms.ml-1 at 2.83 h (tmax); the apparent elimination half-life (t1/2) was 3.73 h; the apparent total body clearance (CL.f-1) was 154 ml.min-1, the mean renal clearance (CLR) was 39.1 ml.min-1 and the apparent fraction of the dose recovered in 24 h urine was 0.22. In uraemic patients, Cmax and tmax were slightly increased and t1/2 was increased to 12-14 h in patients with an endogenous creatinine clearance below 20 ml.min-1. The apparent volume of distribution was decreased. Apparent total and renal clearances were lower in proportion to the degree of renal insufficiency. Linear relationships were found between CL/f, CLR and creatinine clearance (CLCR). The findings suggest that the dose of cefixime needs to be reduced only in patients with severe renal failure.

[Inhibition of bacterial adherence by nitroxoline on cellular adhesion and on urinary catheter surfaces]

Nitroxolin or 5-nitro-8-hydroxyquinoline, used in the treatment of acute or recurrent uncomplicated urinary tract infection (UTI), has been investigated to demonstrate inhibitory effect on bacterial adherence to epithelial cells or solid surfaces. Nitroxolin in vitro and in urine inhibits bacterial adherence of E. coli 38 (MS/MS) on HeLa cells and epithelial cells from human bladder mucosa. In the same conditions, norfloxacin has no effect. Nitroxolin (MIC/8) decreases with a statistically significant difference (p less than 0.001) the bacterial attachment to a urinary catheter surface made in siliconated latex. These results justify the performance of a clinical trial in the prophylaxis of recurrent UTI and the outcome of a bacteriuria associated with indwelling or intermittent bladder catheter.

Plasma and urine concentrations of trimethoprim-sulphadiazine (co-trimazine) in children given one dose per day

Sulphadiazine (SDZ) and trimethoprim (TMP) combined into co-trimazine has a half-life of 10 h in the adult and therefore the use of 1 dose/day has been introduced in the treatment of patients with urinary tract infections (UTI). To investigate the pharmacokinetics of cotrimazine given once daily in infants and children, 14 patients aged 3-49 months were given 0.3-0.4 ml/kg of suspension containing 41 mg SDZ and 9 mg TMP/ml. In all patients the peak plasma levels of SDZ at steady state were greater than 15 mg/l and after 12 h mostly greater than 10 (range 7-22) mg/l. The corresponding levels of TMP were 0.5 and 0.1 (range 0.11-0.48) mg/l. The concentrations in urine at 24 h were in the children about 40 mg/l of SDZ and 10 mg/l of TMP and in the infants 35 and 2 mg/l respectively. Therefore, in the treatment of infants and children with UTI, 1 dose of co-trimazine/day should give adequate plasma and urine levels.

Some pharmacokinetic data about furaltadone and nitrofurazone administered orally to preruminant calves

A single oral dosage of furaltadone and nitrofurazone (14.0 mg/kg) to 5 preruminant calves (in a cross-over trial) revealed mean maximum plasma concentration of 2.5 and 3.5 microgram/ml, respectively, at approximately 3 h after administration. The final elimination half-lives of furaltadone and nitrofurazone were 2.5 and 5 h, respectively. Urinary recovery of these two nitrofurans in 3 calves revealed approximately 2% of the orally administered dose. The renal clearance of the unbound drugs did not differ (for both drugs approximately 0.42 ml/min/kg); furaltadone clearance was strongly related to urine flow.

Pharmacokinetics of cefradine, sulfamethoxazole and trimethoprim and their metabolites in a patient with peritonitis undergoing continuous ambulatory peritoneal dialysis

Cefradine and co-trimoxazole pharmacokinetics were studied in a patient with peritonitis that complicated continuous ambulatory peritoneal dialysis (CAPD). Concentrations in the plasma reached after oral administration of 500 mg cefradine four times daily and 400/80 mg co-trimoxazole four times daily were for cefradine 100 micrograms/ml, for trimethoprim 15 micrograms/ml, and for sulfamethoxazole 100 micrograms/ml, respectively. In the dialysate concentrations were reached of 35-70 micrograms/ml cefradine, 2-5 micrograms/ml trimethoprim and 8-17 micrograms/ml sulfamethoxazole. The values for sulfamethoxazole are regarded too low to be clinically effective. Half-lives, protein binding values and CAPD clearances are presented. Low CAPD clearances were obtained during the night and high values during the day. The dosage yielded too high plasma trimethoprim concentrations, while sulfamethoxazole dialysate concentrations were too low. It seems questionable therefore whether co-trimoxazole can be used orally for the treatment of CAPD peritonitis.

Pharmacokinetics of co-trimazine after single and multiple doses

Plasma and urinary levels of trimethoprim (TMP), sulfadiazine (SDZ) and N4-acetylsulfadiazine (N4-SDZ) were determined after administration of 1 g co-trimazine (equivalent to 180 mg TMP and 820 mg SDZ) (Kombinax) as a single dose and again once daily for 7 days to 6 normal subjects. Both TMP and SDZ were rapidly absorbed from the gastrointestinal tract with peak plasma levels being achieved within 4 h in all subjects. Elimination half-lives ranged from 8 to 13 h for TMP and from 9 to 15 h for SDZ. Approximately 50% of the administered dose of SDZ was recovered in urine within 24 h of the single dose (32% as unchanged drug and 17% as the N4-acetylmetabolite). For TMP, the urinary recovery during the 24 h following the single dose averaged 39%. Mean plasma levels of TMP, SDZ and N4-SDZ at steady state were moderately higher than those observed after a single dose, but no change in absorption or disposition kinetics of these compounds was seen after repeated dosing.

Crystalluria and ciprofloxacin, influence of urinary pH and hydration

Ciprofloxacin is one of the newer 4-quinolones. It combines a high antibacterial activity and a broad spectrum with favourable pharmacokinetic properties. The present study was designed to detect the influence of urinary pH and fluid consumption on crystalluria. Six healthy volunteers aged 25-41 years, 3 of each sex, participated in the study. Single doses of 1,000 and 500 mg of ciprofloxacin were given orally. The urinary pH was varied by giving each subject three different diets: a regular diet, a diet supplemented by ammonium chloride to acidify urine, and a diet supplemented by sodium bicarbonate to obtain alkaline urine. The urine volume and pH were measured and microscopically examined at 37 degrees C immediately after voiding. After the very high dose of 1,000 mg ciprofloxacin the regular diet regimen led to crystalluria in only one subject. Even with this high dose, but with the acidifying regimen, no crystals were observed in any one of the volunteers. When bicarbonate was supplemented 5 to 6 volunteers presented crystals in 22 of the 36 urine samples. 21 of the crystalluric urine samples showed a pH greater than or equal to 7.3. After the usual 500-mg dose and regular diet no crystals were observed at all; only in 3 subjects who received bicarbonate supplement crystals have been seen. In the urine of two subjects crystals emerged 'ex vivo' after some hours of storage at both 37 degrees C and room temperature; these results show the importance of sediment observation at 37 degrees C immediately after voiding to differentiate between real and 'ex vivo' crystalluria. Results of different examinations permit the conclusion that the crystals contain mostly unchanged ciprofloxacin as major component and magnesium as characteristic element. Participation of the metabolite 2 in the crystal formation cannot be excluded. No significant change was observed in blood counts and blood chemistry of any subject. Urinalysis showed no modifications except the eventual presence of the typical drug-related crystals. Hematuria never occurred.

Formaldehyde generation from methenamine salts in spinal cord injury

To achieve effective suppression of bacteriuria in spinal cord injured (SCI) patients, methenamine mandelate and methenamine hippurate are commonly given with ascorbic acid. Since the effectiveness of ascorbic acid as a urinary acidifier has been challenged and as it also has been suggested that methenamine salts do not produce effective urine formaldehyde concentrations in patients with indwelling urethral catheters, we studied two groups of SCI patients to determine (1) the effect of ascorbic acid on urine pH and formaldehyde concentration when administered with methenamine salts; (2) the effect of an indwelling urethral catheter versus intermittent catheterization on formaldehyde concentration in the urine of SCI patients taking methenamine salts; and (3) the relative urine formaldehyde concentrations produced by treatment with methenamine mandelate and methenamine hippurate in SCI patients. Methenamine mandelate produced significantly higher urine formaldehyde concentrations than did methenamine hippurate, especially among patients with intermittent catheterization. Ascorbic acid produced a significant effect on urine pH but not on formaldehyde concentration.

Trimethoprim-sulfadiazine in the horse: serum, synovial, peritoneal, and urine concentrations after single-dose intravenous administration

Six healthy adult mares were given a single IV injection of trimethoprim (TMP)-sulfadiazine (SDZ) at a dosage rate of 2.5 mg of TMP/kg of body weight and 12.5 mg of SDZ/kg. Serum, synovial, peritoneal, and urine TMP-SDZ concentrations were measured serially over a 48-hour period. The highest measured mean concentrations of TMP and SDZ were found in the first (0.5 hour) sample of serum, synovial fluid, and peritoneal fluid. The mean peak concentrations of TMP and SDZ averaged 4.37 micrograms/ml and 21.81 micrograms/ml for serum, 2.95 micrograms/ml and 15.31 micrograms/ml for synovial fluid, and 3.88 micrograms/ml and 19.52 micrograms/ml for peritoneal fluid, respectively. Urine concentrations of the drugs were relatively high and peaked early. The elimination rate for TMP and SDZ averaged 0.41 and 0.26 hour-1, while the elimination half-life was 1.91 and 2.71 hours, respectively, and the volume of distribution averaged 0.59 and 0.52 L/kg, respectively.

High-performance liquid chromatographic analysis of nitroxoline in plasma and urine

A high-performance liquid chromatographic method has been developed for the determination of nitroxoline in 50-microliter plasma and urine samples. A structural analogue of nitroxoline, 8-hydroxyquinoline, was added to the eluent in order to suppress peak asymmetry. Several parameters of the eluent were studied for the optimisation of the chromatographic system. Plasma concentration-time curves were constructed for three volunteers after they had received an oral dose of 100 mg of nitroxoline. Plasma half-life was about 1 h. Within 12 h, about 1% of the dose was excreted in the urine as free nitroxoline and about 30% as conjugated metabolite of the parent compound.

Appropriate nitroxoline dosage regimen design

Clinically used dosage regimen of nitroxoline, three times 100 mg daily, was proved to be inappropriate because the successfulness of medical treatment was rarely sufficient. Nitroxoline, used as urinary antiseptic, exhibits its antibacterial activity in concentrations higher than 6 mg/l, as demonstrated in many "in vitro" experiments. This work deals with the most appropriate nitroxoline dosage form as well as with the optimal dosage regimen design. The data were obtained by the aid of the suitable pharmacokinetic model and multiple dosing simulation on analog-hybrid computer EAI 580. From the several studied alternatives two usable dosage forms with the necessary dose and corresponding dosage interval were selected.

Clinical pharmacokinetics of nitroxoline

14C-Nitroxoline was given orally to the rats, and its distribution as well as plasma and bile levels were determined autoradiographically and by the aid of radioactivity measurements, respectively. Nitroxoline was also given to the human volunteers orally and intravenously in three various doses and the corresponding urine concentrations of unconjugated and conjugated nitroxoline were determined spectrophotometrically. A pharmacokinetical model was generated on the basis of the results. The curve fitting procedure between total nitroxoline cumulative quantities in urine and the model response simulated on analog-hybrid computer enabled the evaluation of the validity of the chosen model as well as of the identification of its parameters.

Influence of probenecid on serum levels and urinary excretion of cinoxacin

Serum levels and urinary excretion of cinoxacin were examined in healthy individuals after a two-step intravenous infusion in the presence and absence of probenecid. After dosing cinoxacin alone, steady-state serum levels were approached in 1 h and were maintained for an additional 2 h with a reduced infusion rate. After probenecid pretreatment, serum levels of cinoxacin continued to increase during 3 h of infusion, reaching levels approximately double those obtained with cinoxacin alone. The mean elimination half-life of cinoxacin from serum was increased from 1.3 to 3.5 h in the presence of probenecid, and renal clearance was significantly reduced, with 46% of dosed drug appearing in 7-h urines of probenecid-treated subjects compared with 68% in subjects receiving cinoxacin alone. Probenecid had no apparent influence on cinoxacin distribution in the body but caused a significant decrease in the rate of cinoxacin extrarenal elimination, possibly due to competition for a common metabolic pathway.