Pharmacokinetics of rufloxacin in healthy volunteers after repeated oral doses

Rufloxacin Eyedrops: Effect of Different Formulations on Ocular Pharmacokinetics in Rabbits

PURPOSE

To evaluate the aqueous humor pharmacokinetics of rufloxacin in rabbits after topical administration of different formulations, and to individuate the ones showing the best pharmacokinetic profile.

METHODS

Six formulations were instilled in rabbit eyes: two pH 7.2 suspensions of non-salified rufloxacin base, or zwitterion (RUF), one of which was viscosized with tamarind seed polysaccharide (TSP); two pH 7.2 solutions of RUF obtained using hydroxypropyl-beta-cyclodextrin (CD), one of which was viscosized with TSP; and two pH 5.0 solutions of rufloxacin hydrochloride (RUF-HCl ), one of which was viscosized with TSP. At different times after administration, samples of aqueous humor were withdrawn and analyzed by high-pressure liquid chromatography. The main pharmacokinetic parameters of RUF in the aqueous humor produced by the different formulations were calculated and statistical differences were assessed.

RESULTS

The best results, in terms of aqueous humor bioavailability, were observed with two TSP-viscosized formulations: a solution of the hydrochloride (TSP/RUF-HCl) and a suspension of the base (TSP/RUF), followed by the non-viscosized solution of RUF-HCl. The formulations containing CD-solubilized RUF were much less effective.

CONCLUSIONS

The present data confirm the significant availability-enhancing properties of tamarind seed polysaccharide, and indicate that solubilization of RUF with hydroxypropyl-beta-cyclodextrin (CD/RUF) results in decreased drug availability with respect to standard formulations. Two of the TSP-viscosized formulations (RUF suspension and RUF-HCl solution) produced aqueous humor RUF concentrations in the range of activity against Enterobacteriaceae and Pseudomonas aeruginosa, thus warranting further studies on applications of rufloxacin in ocular therapy.

Comparative pharmacokinetics and pharmacodynamics of the newer fluoroquinolone antibacterials

A number of new fluoroquinolone antibacterials have been released for clinical use in recent years. These new agents exhibit enhanced activity against Gram-positive organisms while retaining much of the Gram-negative activity of the earlier agents within the same class. The pharmacokinetics of most of these agents are well described including serum pharmacokinetics, tissue and fluid distribution, and pharmacokinetics in renal and hepatic disease. When compared with earlier agents within this class (i.e. ciprofloxacin), the newer agents retain the wide distribution characteristics; however, they exhibit a more prolonged elimination, which, in part, supports single daily administration for these agents. Based on their predominant renal elimination, dosage adjustment is necessary in the presence of renal disease for ciprofloxacin, levofloxacin, gatifloxacin and sitafloxacin. Drug interactions, particularly with multivalent cations (calcium/aluminium-containing antacids and iron products), remain a problem for the newer agents, resulting in reduced absorption requiring separate administration times to maximise bioavailability. However, the newer agents do not appear to interfere significantly with the cytochrome P450 system, thus minimising the potential for interactions with other drugs metabolised by this system. The pharmacodynamic properties of the fluoroquinolones have been well described. The bactericidal activity is maximised when the ratios of peak plasma drug concentration (Cmax): minimum inhibitory concentrations (MIC) or area under the concentration-time curve (AUC): MIC exceed specific threshold values. Knowledge of the pharmacodynamic relationships allows for appropriate drug selection and enables design of dosage regimens to maximise the bactericidal activity. Therapeutic drug monitoring of the fluoroquinolones may provide a means of optimising the dosage regimen in certain clinical situations (that is, meningitis and hospitalised pneumonias) with the goals of achieving a more predictable therapeutic response and minimising the potential for the development of resistance.

Analysis of fluoroquinolones in biological fluids by high-performance liquid chromatography

High-performance liquid chromatographic methods for the analysis of fluoroquinolones in biological fluids are reviewed. In particular, sample preparation and handling procedures, chromatographic conditions, and detection methods are discussed. A summary of published high-performance liquid chromatographic assays for individual fluoroquinolones is included.

Randomized, double-blind comparison of single-dose regimens of rufloxacin and pefloxacin for acute uncomplicated cystitis in women. French Multicenter Urinary Tract Infection-Rufloxacin Group

In a double-blind, randomized, multicenter study, 463 adult women with symptomatic acute uncomplicated cystitis were treated orally with either a 400-mg single dose of rufloxacin (n = 226) or an 800-mg single dose of pefloxacin (n = 237). Escherichia coli (78%) and Proteus mirabilis (7%) were the most common isolates from 350 patients with significant pretreatment bacteriuria (uropathogens, > or = 10(5) CFU/ml). In the intention-to-treat analysis of patients with significant pretreatment bacteriuria, 343 patients were assessed for bacteriological outcome and 345 were assessed for clinical outcome. The bacteriological cure rate was 88% in the rufloxacin group and 84% in the pefloxacin group (95% confidence interval [CI] for difference in proportions, -4 to 12%), while the clinical resolution rate was 85 and 84%, respectively (95% CI, -8 to 9%). The per-protocol analysis demonstrated that among the 264 assessable patients, the bacteriological cure rate obtained with rufloxacin at 4 weeks of follow-up was comparable to that with pefloxacin (91 versus 85%; 95% CI, -3 to 15%). Among 295 clinically assessable patients, the clinical resolution rate at 4 weeks of follow-up was 89% in the rufloxacin group and 88% in the pefloxacin group (95% CI, -6 to 10%). Potentially drug-related adverse events occurred in 19% of the rufloxacin patients and in 18% of the pefloxacin patients. A single oral dose of 400 mg of rufloxacin is as effective and safe as a single oral dose of 800 mg of pefloxacin for the treatment of acute uncomplicated cystitis in women.

Biliary excretion of rufloxacin in humans

Rufloxacin is a new once-daily antibacterial fluoroquinolone with a long half-life. The aim of the present study was to evaluate the plasma and biliary kinetics and biliary and urinary excretion of rufloxacin in patients with extrahepatic cholestasis. Twelve patients with total external percutaneous transhepatic biliary drainage were given a single oral dose of 400 mg of rufloxacin. Plasma, bile, and urine samples and fractions were collected over 72 h after drug administration. Rufloxacin and its major metabolite, the N-desmethyl derivative, were measured by high-performance liquid chromatography. Maximum rufloxacin concentrations in plasma and bile (means +/- standard deviations) were 4.05 +/- 1.38 micrograms/ml and 8.24 +/- 7.16 micrograms/ml, respectively, and were reached in 4.2 +/- 3.0 h and 4.2 +/- 3.5 h, respectively. The terminal elimination half-life of rufloxacin in plasma was 45.1 +/- 13.5 h. Apparent plasma clearance was 31.3 +/- 10.5 ml/min, while biliary clearance was 0.4 +/- 0.2 ml/min and renal clearance was 12.7 +/- 6.0 ml/min. In 72 h, 0.9% +/- 0.8% of the dose given was recovered in bile and 27.2% +/- 12.0% was recovered in urine. Biliary concentrations exceeded the MICs of most common biliary tract pathogens for at least 24 h after administration. The broad antibacterial spectrum of rufloxacin and its high and prolonged biliary concentrations suggest that this drug may be useful for treatment of biliary tract infections.

Double-blind, comparative study of rufloxacin once daily versus amoxicillin three times a day in treatment of outpatients with exacerbations of chronic bronchitis

In a double-blind, randomized, multicenter study, the efficacy and safety of two dosage schedules of rufloxacin once daily were compared with those of amoxicillin three times a day in the treatment of 192 outpatients with exacerbations of chronic bronchitis. Rufloxacin was given as a single oral dose of 400 mg on day 1 and single daily doses of 200 mg on the subsequent 9 days (n = 64) or as 300 mg on day 1 and then 150 mg daily for 9 days (n = 63); amoxicillin was given as 500 mg orally three times a day for 10 days (n = 65). Clinical and bacteriological assessments were carried out before treatment, between study days 3 and 5, and at days 1 and 8 after treatment. Pretreatment cultures were positive for 139 patients, the most frequently isolated pathogens being Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae. Clinical success rates were comparable in the three groups (94, 95, and 98%, respectively), as were bacteriological success rates at the end of treatment (93, 95, and 91%, respectively) and at follow-up (88, 95, and 98%, respectively). The power to detect a significant 15% difference in cure rates was 74.9%. Follow-up bacteriological failures from pneumococcal infection were 18% in both rufloxacin groups combined and 5% in the amoxicillin group. The 200-mg dose regimen achieved average steady-state concentrations in plasma higher than did the 150-mg dose regimen (3.75 versus 2.72 micrograms/ml). Adverse events occurred in 11 and 13 patients, respectively, on rufloxacin and 8 on amoxicillin. This study shows that rufloxacin once daily ay be a possible option for the treatment of acute exacerbations of chronic bronchitis. The 200-mg daily oral dose preceeded by a loading dose of 400 mg displays a better pharmacokinetic profile than the lower dose.

Multiple-dose pharmacokinetics of rufloxacin in patients with cirrhosis

The multiple-dose pharmacokinetics of rufloxacin were investigated in 13 patients with biopsy-proven cirrhosis and in 5 healthy controls. Rufloxacin was administered once a day for 5 consecutive days, starting with a loading dose of 400 mg on day 1 and 200 mg on the subsequent days. Plasma and urinary drug concentrations were determined by high-performance liquid chromatography and a microbiological assay. A one-compartment model applied to the high-performance liquid chromatography data was used to calculate the pharmacokinetic parameters of rufloxacin. In the controls rufloxacin had a low plasma clearance (41 +/- 4 ml/min, mean +/- S.E.M.), a long half-life (30.1 +/- 3.9 hr), a large area under the plasma concentration vs. time curve (171 +/- 18 micrograms.hr/ml) and a low renal clearance (18 +/- 2 ml/min). No appreciable differences were observed in the pharmacokinetic parameters between patients with various degrees of liver-function impairment (modified Child-Pugh score ranging from 5 to 13). In these patients plasma clearance was slightly reduced (-32%), but this decrease was caused by a marked reduction in renal clearance (-65%) rather than nonrenal clearance, which remained unchanged (22 ml/min in cirrhotic patients vs. 23 ml/min in controls). A significant (p < 0.01) correlation was found between creatinine clearance and both rufloxacin renal clearance (r = 0.769) and rufloxacin plasma clearance (r = 0.681). The elimination half-life and the area under the plasma concentration vs. time curve were moderately increased in cirrhotic patients (+33% and +26%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of magnesium-aluminum hydroxide antacid on absorption of rufloxacin

The present study was designed to determine the effects of an antacid suspension containing magnesium hydroxide and aluminum hydroxide (30 ml of Maalox) on the oral bioavailability of rufloxacin (400 mg). Rufloxacin was administered orally to 12 healthy volunteers according to a randomized, balanced, crossover design. Three treatments were administered to each subject, with a 10-day washout period between treatments; the treatments included rufloxacin alone, rufloxacin taken 5 min after antacid, and rufloxacin taken 4 h before antacid. Administration of antacid within 5 min before the administration of rufloxacin resulted in a substantial decrease in rufloxacin absorption, with a mean percent relative bioavailability compared with control values of 64% (range, 42 to 77%). Administration of antacid 4 h after the administration of rufloxacin slightly affected the absorption of the quinolone (mean relative bioavailability, 87%; range, 51 to 110%). Antacids that contain magnesium and aluminum salts reduce the absorption of rufloxacin. The extent of this interaction depends on the time that elapses between administration of the two drugs.

Comparative activity of the new fluoroquinolone rufloxacin (MF 934) against clinical isolates of gram-negative and gram-positive bacteria

The antibacterial activity of the new fluoroquinolone rufloxacin (MF 934) was evaluated against 1095 clinical isolates and compared with that of other quinolones and various commonly used antibiotics. Rufloxacin was highly effective against members of the Enterobacteriaceae, inhibiting 98% of the isolates at a concentration of 1 mg/l. Ninety-two percent of Aeromonas hydrophila and 65% Acinetobacter strains tested were inhibited by 1 mg/l of rufloxacin, whereas 98% of methicillin-susceptible and 87% of methicillin-resistant Staphylococcus aureus strains and 76% of coagulase-negative staphylococci strains required 4 mg/l for growth inhibition. The MIC values of rufloxacin for most bacteria were 4-16 times higher than those of ciprofloxacin and norfloxacin. Rufloxacin had little activity against xanthomonads, pseudomonads and enterococci. Approximately 95-96% of isolates of Pseudomonas aeruginosa were inhibited by 2 mg/l of ciprofloxacin and norfloxacin as compared to 29% inhibited by rufloxacin at this concentration.

Pharmacokinetics of rufloxacin in patients with impaired renal function

The pharmacokinetics of rufloxacin were investigated in normal subjects and in patients with various degrees of renal failure after the administration of a single oral 400-mg dose. Twenty-four subjects were classified by glomerular filtration rate (GFR) normalized for body surface area. Group 1 subjects had GFRs of > 80 ml/min, group 2 subjects had GFRs from 30 to 80 ml/min, group 3 subjects had GFRs from 8 to 29 ml/min, and group 4 subjects had GFRs of < 8 ml/min. The patients in group 4 were on continuous peritoneal dialysis or underwent hemodialysis 48 h after dosing. Plasma and urinary rufloxacin concentrations were determined by high-performance liquid chromatography. A two-compartment model was used to calculate rufloxacin pharmacokinetic parameters. Apparent total body clearance of the drug was linearly related to GFR (r = 0.696; P < 0.01). The elimination half-life increased proportionally with the severity of renal impairment, with values of 30 +/- 3, 36 +/- 5, and 44 +/- 3 h in groups 1, 2, and 3, respectively. In patients with moderate renal failure, dosage adjustment of rufloxacin is not needed. The rufloxacin dose interval should be prolonged to 48 h as the GFR falls below 30 ml/min/1.73 m2.

Rufloxacin once daily versus ofloxacin twice daily for treatment of complicated cystitis and upper urinary tract infections. Italian Multicentre UTI Rufloxacin Group

The efficacy and safety of rufloxacin once daily was compared with that of ofloxacin b.i.d. for therapy of complicated cystitis and upper urinary tract infections. Eighty-three patients were randomly assigned to receive rufloxacin as a loading dose of 400 mg on the first day, followed by 200 mg s.i.d., and 80 received ofloxacin 300 mg b.i.d. Both agents were administered orally for a median duration of eight days. Bacterial elimination rates after treatment were 90% for rufloxacin and 81% for ofloxacin. Half of the treatment failures occurred in patients with infections caused by uropathogens that became either less sensitive or resistant to the quinolones being studied. At a two-week follow-up, recurrences had not occurred in any of the rufloxacin patients and had occurred in 17% of the ofloxacin patients. Minor adverse reactions were reported by 12 and 13 patients, respectively. Rufloxacin once daily is as effective as ofloxacin b.i.d. for the treatment of complicated cystitis and upper urinary tract infections.

Pharmacokinetics of rufloxacin once daily in patients with lower respiratory tract infections

The pharmacokinetic properties of rufloxacin, a new quinolone antibacterial agent, were evaluated in ten patients with lower respiratory tract infections. Patients were given 400 mg of rufloxacin once a day for seven to nine days. Plasma concentrations of the drug were determined by high-performance liquid chromatography and bioassay at regular intervals during treatment. After the first administration, maximal plasma concentrations were 3.17 +/- 0.36 mg/l (mean +/- SEM) and were reached at 4.2 +/- 0.7 h. At the end of treatment peak plasma concentrations increased to 7.26 +/- 0.52 mg/l. Elimination half-life was 38.2 +/- 2.9 h, with a mean extent of accumulation of 2.96 +/- 0.30. Treatment was well tolerated, with no abnormalities noted during routine laboratory examinations. Two days after the last administration, measurable levels of rufloxacin were still observed in plasma, indicating that the long half-life of rufloxacin assures valuable antibacterial activity even after discontinuation of treatment.