[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.