Treatment of Francisella infections via PLGA- and lipid-based nanoparticle delivery of antibiotics in a zebrafish model.

We tested the efficiency of 2 different antibiotics, rifampicin and oxolinic acid, against an established infection caused by fish pathogen Francisella noatunensis ssp. orientalis (F.n.o.) in zebrafish. The drugs were tested in the free form as well as encapsulated into biodegradable nanoparticles, either polylactic-co-glycolic acid (PLGA) nanoparticles or nanostructured lipid carriers. The most promising therapies were PLGA-rifampicin nanoparticles and free oxolinic acid; the PLGA nanoparticles significantly delayed embryo mortality while free oxolinic acid prevented it. Encapsulation of rifampicin in both PLGA and nanostructured lipid carriers enhanced its efficiency against F.n.o. infection relative to the free drug. We propose that the zebrafish model is a robust, rapid system for initial testing of different treatments of bacterial diseases important for aquaculture.

Treatment of vibriosis in European sea bass larvae, Dicentrarchus labrax L., with oxolinic acid administered by bath or through medicated nauplii of Artemia franciscana (Kellogg): efficacy and residual kinetics.

European sea bass larvae were challenged by bath with Listonella anguillarum strain 332A, 2.5×10(7) CFUmL(-1) for 1h. Fish either received no treatment or oral treatment with Artemia franciscana (Kellog) nauplii enriched with oxolinic acid, or bath treatments with oxolinic acid. Medication commenced 1day following challenge and was performed on days 1, 3 and 5 post-challenge at a dosage of 20mgL(-1) for 2h for bath treatments, while two doses each of 750 nauplii per fish were administered daily for five consecutive days in oral treatments. Cumulative mortality reached 96% for the unmedicated challenged group, 32% in the group receiving bath treatments and 17% in the group receiving medicated nauplii. Pharmacokinetic parameters of oxolinic acid were calculated in sea bass larvae, for both treatments. Steady-state concentrations of oxolinic acid of 48.0 and 75.2µgg(-1) were achieved for bath treatment and oral treatment, respectively, while the elimination half-life was calculated to be 25.1h for bath treatment and 21.7h for oral treatment.

Pharmacokinetics of nalidixinic acid and oxolinic acid in healthy women.

The pharmacokinetics of oral nalidixic acid (NA, 1 gm 4 times a day) and oxolinic acid (OA, 750 mg 2 times a day) administered for 7 days were studied in the same 10 healthy women on the first, third, and seventh days of the treatment. The peak concentrations of NA + OH-NA (hydroxynalidixinic acid) in serum at 2 to 3 hr were 34 mug/ml (total) and 23 mug/ml (unconjugated) on the first day and nearly two times higher on the third and seventh days; 82% to 85% of these amounts were NA. The protein-free fraction of NA + OH-NA was 8.8% to 18.3%. The total concentration of NA + OH-NA in urine was 1,220 to 2,700 mug/ml, the unconjugated concentration, 250 to 350 mug/ml, and the chemotherapeutically active concentration, 55 to 75 mug/ml. In steady state the 24-hr recovery of the total drug was 79% of the daily dose. The excretion rate in urine was 591 to 853 mg/6 hr. The OA concentration in serum was very low on the first day of the treatment, but increased to 4- to 5-fold on the third and seventh days: 6.2 to 6.4 mug/ml (total) and 3.3 to 3.6 mug/ml (unconjugated). The protein-free OA represented 19% to 23% of the total amount. The modest initial serum concentrations of OA were confirmed by the low urine concentrations on the first day. In steady state the OA concentration in urine was 570 mug/ml (total) and 35 mug/ml (unconjugated), and the 24-hr recovery, 49% and 3%, respectively. The microbiologic assay gave somewhat higher concentrations of the active drug than did the chemical assay. When taken with food, the excretion of OA in urine was retarded by 6 hr but the 48-hr recovery was not decreased.

Cross resistance between oxytetracycline and oxolinic acid in Aeromonas salmonicida associated with alterations in outer membrane proteins.

Oxytetracycline resistant mutants of Aeromonas salmonicida isolated from mutation frequency experiments showed decreased susceptibility to oxolinic acid. Outer membrane preparations of these resistant mutant strains revealed a major protein, with a molecular mass of approximately 37 kDa, which was not present in significant quantities in the parent strain.

Clinical pharmacology of oxolinic acid in young dairy calves.

The in vitro sensitivity to oxolinic acid shown by pathogenic gram-negative bacterial isolates from young calves with diarrhea, pneumonia, and septicemia was investigated by the bute dilution method. Minimal bactericidal concentrations of the drug for 65.5% of the isolates were less than or equal to 1.56 mug/ml and for 90%, less than or equal to 6.25 mug/ml. Cross resistance between oxolinic acid and chloramphenicol, streptomycin, neomycin, colistin, ampicillin, gentamicin, and oxytetracycline was not observed. Oxolinic acid was orally administered to a group of calves at dose levels of 12.5 to 57.0 mg/kg, and sodium oxolinate was intramuscularly injected in another group of calves at dose levels of 12.5 and 20 mg/kg. In the 1st group, oxolinic acid was detected in blood serum 15 minutes later; peak serum concentrations averaged 25 mug/ml at 10 hours after treatment with 50 mg of the drug/kg and 3 mug/ml at 7 hours, with 12.5 mg of the drug/kg. In the 2nd group, the dose level of 20 mg of sodium oxolinate/kg resulted in mean peak serum concentration of 4 mug/ml, observed 1 hour after the drug was injected. The half-life of the drugs in serum was approximately 3.5 hours after they were orally or intramuscularly given. These investigations indicate that oxolinic acid could be used in the treatment of the common calf diseases.

[Oxolinic acid treatment of urinary sepsis in patients with renal insufficiency]. / Trattamento con l'acido ossolinico delle sepsi urinarie nei pazienti con insufficienza renale.

The effect of oxolinic acid, administered at the rate of 750 mg twice/day, has been studied on 31 patients with urinary tract infections. Many of them had a marked impairment of renal function due to nephropathies of various origin. Favourable results, with sterile urine and complete remission of symptoms, were obtained in 73.3%. Patients who were resistant to previous different therapies, were successfully treated. Oxolinic acid was on the whole well tolerated and proved to be effective also in patients with impaired renal function. In some of the latter an improvement in renal function occurred as a result of the effective urinary infection care. The tolerability of oxolinic acid was good: only one patient interrupted the treatment because of insomnia; other 4 had transient and mild side-effects.

Combined oral and local therapy for the dissolution of urinary calculi.

The factors underlying the formation of Ca-phosphate and struvite calculi, as well as the present possibilities for oral and local therapy, their advantages and drawbacks are discussed in the light of published evidence. In this context a clinical case of multiple injuries is reported in which practically complete chemolitholysis has been achieved by combined oral and local therapy. The rapid growth of the calculi and their alarming tendency to recurrence in case of inadequate treatment is emphasized. The therapeutic method used in this case is regarded as suitable for practical purposes.

[The characteristics of oxolinic acid transport in the blood of dogs and monkeys when administered intramuscularly and perorally]. / Osobennosti transporta oksolinovoi kisloty v krovi u sobak i obez'ian pri vmutrimyshechnom i peroral'nom vvedenii.

A possibility of testing oxolynic acid (OA) transport in blood of animals by its bactericidal effect was studied experimentally on macaques and non-pedigree dogs (intramuscular and peroral administration). Kinetics of accumulation and elimination of OA and its derivatives exhibiting bactericidal effect makes it possible to predict optimum scheme of using these drugs in prevention and treatment of radiation disease.

Differential gene expression in black tiger shrimp, Penaeus monodon, following administration of oxytetracycline and oxolinic acid.

The intensification of shrimp farming systems has led to the spreading of a variety of bacterial and viral diseases that continue to plague the shrimp industry worldwide. Efforts to combat these pathogenic organisms include the use of immunostimulants, probiotics, vaccines and antibiotics. Although a few studies have already reported on the effects of various stimuli on shrimp, the effect of antibiotics, particularly on the changes in the shrimp transcriptomic profile have yet to be reported. Here we show that injecting shrimp with oxytetracycline and oxolinic acid alters the expression of genes in the black tiger shrimp, Penaeus monodon, lymphoid organ. These antibiotics, especially oxylinic acid, down-regulated the expression of a few immune-related genes, most notably penaeidin, proPO, clotting protein, profilin and whey acidic protein.

Oxolinic acid in the trout: bioavailability and tissue residues.

A study was performed on the serum bioavailability and tissue elimination of oxolinic acid in the trout. The compound was added to the diet and administered at a dosage-level of 12 mg/kg/day for 7 consecutive days. The study utilized an analytical technique, high performance liquid chromatography, which has been described in detail here. The results obtained demonstrate that serum concentrations higher than the MIC for the control of the target pathogens (Aeromonas and Yersinia) can by sustained throughout the treatment period. The same positive results were observed in the tissues. Besides, on the base of a tolerance level of 0.05 ppm for the residue levels of oxolinic acid in the edible tissues (muscle mass and skin), a withdrawal time of six days after interruption of the prescribed treatment can be proposed.

Pharmacokinetics of oxolinic acid in sea-bass, Dicentrarchus labrax (L., 1758), after a single rapid intravascular injection.

The pharmacokinetics of oxolinic acid was studied in sea-bass (Dicentrarchus labrax). The fish were kept in seawater at 15.2 degrees C with a 12 h/12 h photoperiod. Oxolinic acid was injected in the caudal vein of anaesthetized sea-bass in a single rapid intravascular administration at a dose of 10 mg/kg of body weight. Plasma concentrations of oxolinic acid were determined using two analytical methods, a classic plate diffusion bioassay using Escherichia coli and a high performance liquid chromatography (HPLC) using solid phase extraction with an internal standard and a U.V. detection. The mean recoveries were 99.6% and 110.8% and determination limits were 0.04 microg/mL and 0.02 microg/mL, for the bioassay and the HPLC respectively. Compared to other fish species, the oxolinic acid was rapidly (absorption half life, t(a1/2) = 0.69 h) distributed to body tissues outside the blood volume (volume of central compartment, Vc = 0.4 L/kg) and presented a large volume of distribution (Vdss = 2.55 L/kg). Considering its disappearance from the central compartment (rate constant: central-eliminated, k10 = 0.16 h[-1]) and its total body clearance (Cl[t] = 0.066 L/kg x h), the elimination phase of the oxolinic acid in sea-bass was shorter than in trout kept in freshwater, and longer than in salmon in seawater. Consequently, the area under the concentration-time curve (AUC = 157 microg x h/mL) and the mean residence time (MRT = 42 h) were relatively low and short, respectively.

Pharmacokinetics of a discontinuous absorption process of oxolinic acid in turbot, Scophthalmus maximus, after a single oral administration.

1. The pharmacokinetics of oxolinic acid have been studied in 500 g turbot (Scophthalmus maximus). The fish were kept in seawater at 16 degrees C with a 15 h/9 h photoperiod. Oxolinic acid was administered orally via a stomach tube at a single dose of 10 mg/kg of body weight. Serum concentrations of oxolinic acid were determined by a (HPLC) using liquid phase extraction with an internal standard and a fluorescence detection. 2. The pharmacokinetic process was not significantly sex-influenced. The short elimination phase of the oxolinic acid in turbot after oral administration was similar to the elimination after intravascular administration. The serum concentration profile of oxolinic acid was better described by a discontinuous absorption model than by compartment models using continuous absorption processes. The absorption of oxolinic acid in turbot was characterized by two distinct phases after a lag time of about 2 h. A time (Tmax) of 12 h was necessary to reach the peak serum concentration (Cmax) of 1.41 microg/ml. The oral bioavailability was 27.9%. 3. Based on the minimum inhibitory concentration for susceptible strains, and especially Vibrio anguillarum, the oxolinic acid could be effective in turbot after an oral treatment of 10 mg/kg/day.

Elimination of oxolinic acid in eggs after oral treatment of laying hens.

1. Oxolinic acid is often used in poultry as a therapeutic agent. The aim of this study was to determine both its elimination into eggs, following oral dosing through the drinking water (12 mg/kg/d) or diet (13 mg/kg/d) for 5 d and its plasma concentrations. 2. Samples (albumen, yolk, plasma) were analysed by high performance liquid chromatography (HPLC) with fluorimetric detection. The limits of quantification were 10 ng/g in plasma and 5 ng/g in albumen and yolk. Residues were much higher in albumen than in plasma, whereas they were lower in yolk. 3. 95% of the overall oxolinic acid detected in eggs was concentrated in the albumen. 4. Detectable residues persisted for 9 d and 7 d, respectively, in albumen and yolk after the treatment was discontinued.

The correlation of serum luteinizing hormone levels with the induction of Leydig cell tumors in rats by oxolinic acid.

Studies were performed to examine the mechanism by which testicular Leydig cell tumors are induced in rats by administration of the antimicrobial agent oxolinic acid (1-ethyl-1,4-dihydro-6,7-methylenedioxy-4-oxo-3-quinolinecarboxylic acid). In these studies, the effects of oxolinic acid on serum levels of luteinizing hormone (LH), testosterone, and prolactin and the binding of testosterone to prostatic androgen receptors were examined. In a long-term hormonal study, male Wistar rats were fed a diet containing oxolinic acid at 0, 100, 1000, or 3000 ppm for 104 weeks. A statistically significant increase in serum LH levels was observed at 1000 and 3000 ppm, but no dose of oxolinic acid had a significant effect on serum testosterone levels. Serum LH levels were no longer elevated above control levels within 2 weeks of cessation of the administration of oxolinic acid. Oxolinic acid was found to have no effect on the rate of clearance of exogenous LH from the circulation. Serum prolactin levels were decreased by the administration of oxolinic acid. The increase in serum LH induced by oxolinic acid was completely blocked by the intraperitoneal injection of the dopamine antagonist haloperidol (2 mg/kg). In addition, no significant affinity of oxolinic acid for androgen receptors was found in an in vitro study. These findings suggest that: (1) oxolinic acid induces Leydig cell tumors in rats by chronically stimulating the release of LH from the pituitary, (2) the mechanism of stimulating the release of LH involves facilitation of the dopaminergic systems in the hypothalamus-pituitary axis, and (3) oxolinic acid has no effect on androgen-mediated feedback inhibition.

A single-dose pharmacokinetic study of oxolinic acid and vetoquinol, an oxolinic acid ester, in cod, Gadus morhua L., held in sea water at 8 degrees C and in vitro antibacterial activity of oxolinic acid against Vibrio anguillarum strains isolated from diseased cod.

The pharmacokinetic properties of the antibacterial agent oxolinic acid and vetoquinol, the carbitol ester of oxolinic acid, were studied after intravenous (i.v.) and oral (p.o.) administration to 100-150 g cod, Gadus morhua L., held in sea water at 8 degrees C. Following i.v. injection, the plasma drug concentration-time profile showed two distinct phases. The distribution half-life (t1/2alpha) was estimated at 1.3 h, the elimination half-life (t1/2beta) as 84 h and the total body clearance (Cl(T)) as 0.047 L kg(-1) h(-1). The volume of distribution at steady state, Vd(ss) was calculated to be 5.5 L kg(-1), indicating good tissue penetration of oxolinic acid in cod. Following p.o. administration of oxolinic acid or vetoquinol, the peak plasma concentrations (C(max)) of oxolinic acid and the time to peak plasma concentrations (T(max) were estimated to be 1.2 and 2.5 microg mL(-1) and 24 and 12 h, respectively. The bioavailabilities of oxolinic acid following p.o. administration of oxolinic acid and vetoquinol were calculated to be 55 and 72%, respectively. The in vitro minimum inhibitory concentration (MIC) values of oxolinic acid against three strains of Vibrio anguillarum isolated from diseased cod were 0.016 microg mL(-1) (HI-610), 0.250 microg mL(-1) (HI-618) and 0.250 microg mL(-1) (HI-A21). Based on a MIC value of 0.016 microg mmL(-1) a single p.o. administration of 25 mg kg(-1) of oxolinic acid maintains plasma levels in excess of 0.064 microg mL(-1), corresponding to four times the MIC-value, for approximately 12 days. The analogous value for a single p.o. dose of 25 mg kg(-1) of oxolinic acid administered as vetoquinol was 13 days.

The efficacy of a single intraperitoneal injection of oxolinic acid in the treatment of bacterial infections in goldsinny wrasse (Ctenolabrus rupestris) and corkwing wrasse (Symphodus melops) studied under field and laboratory conditions.

The efficacy of a single intraperitoneal injection of oxolinic acid to control an outbreak of atypical Aeromonas salmonicida infection in goldsinny wrasse (Ctenolabrus rupestris) and in the treatment of systemic vibriosis in corkwing wrasse (Symphodus melops) was examined. In addition a field study was performed to examine the effect of medication on the survival rate of goldsinny wrasse in Atlantic salmon cages. Four groups of wild caught goldsinny wrasse, each of 50 fish, were treated with an intraperitoneal injection of propylene glycol:saline (50:50) (control) or 50 mg/kg oxolinic acid at a concentration of 50 mg/mL. Three days after medication the fish in all groups were treated by an intraperitoneal injection of prednisolone acetate and an increase in seawater temperature from 9.0 to 11.5 degrees C. Cumulative mortalities were 18% in the two groups treated with oxolinic acid and 94 and 100% in the unmedicated control groups, giving a 'relative percentage survival' (RPS) value of 82%. A laboratory maintained population of originally wild caught corkwing wrasse experiencing high daily mortality was treated with oxolinic acid (50 mg/kg) or propylene glycol:saline (control). Cumulative mortalities were 84% (control) and 42% (oxolinic acid medicated group) giving an RPS value of 50%. In a field investigation using goldsinny wrasse approximately 30% were medicated with oxolinic acid (50 mg/kg) prior to stocking in cages with Atlantic salmon. In two of three cages the cumulative mortality was significantly lower (P = 0.025 and P < 0.001) in the medicated groups.