Pharmacokinetics of enrofloxacin HCl-2H2O (Enro-C) in dogs and pharmacokinetic/pharmacodynamic Monte Carlo simulations against Leptospira spp

Treatment of Bovine Leptospirosis with Enrofloxacin HCl 2H2O (Enro-C): A Clinical Trial

Pharmacokinetics/pharmacodynamics ratios of enrofloxacin HCl-2H2O (enro-C) in cows to treat bovine leptospirosis prompted this clinical trial in the highlands (HL) and the tropics (TL) in Mexico. In the HL, 111 Holstein-Friesian cows were included and 38 F1 Zebu–Holstein/Friesians in the TL. Affected cows were randomly divided into two treatment groups, both in the HL and TL. PCR and MAT tests were performed before and after treatment. Treatments in both groups were administered for 5 d with either IM injections of enro-C or streptomycin/penicillin-G. Reproductive performance data were gathered for 90 d. The cows treated with enro-C became PCR negative: 87.5% and 78.94% on day 5, 92.85% and 94.73% on day 28 (in the HL and TL, respectively). For streptomycin/penicillin-G, the same values were 65.45% and 70.90% on day 5, and 73.68% twice on day 28 in the HL and TL, respectively. In both groups and geographical settings, the MAT titers dropped on day 28 but remained above reference values usually considered negative. The gestation rates were: 86.53% and 79.06% and 88.88% and 87.5% for the HL and TL, either with enro-C or streptomycin/penicillin-G, respectively. This is the first report of successful treatment with a fluoroquinolone derivative in treating bovine leptospirosis with a high bacteriological cure rate.

Successful treatment of recurrent subclinical mastitis in cows caused by enrofloxacin resistant bacteria by means of the sequential intramammary infusion of enrofloxacin HCl-2H2O and ceftiofur HCl: a clinical trial

Background

Recurrent subclinical mastitis (RScM) due to resistant bacteria has low clinical and bacteriological cure rates, often requiring the culling of cows. The sequential intra-mammary administration of enrofloxacin hydrochloride-dihydrate (enro-C) followed by ceftiofur HCl may be useful for treating these cases.

Objectives

This study assessed the bacteriological and clinical cure-efficacies of the sequentially intramammary administration of enro-C, followed by ceftiofur HCl to treat RScM in Holstein/Friesian cows.

Methods

This trial was conducted in a herd with a high prevalence of RScM, and 20 Holstein/Friesian cows were included: 45% suffering subclinical mastitis and 38.9% of the mammary quarters affected. Twenty-nine bacterial isolates in vitro resistant to enro-C were obtained (coagulase-negative Staphylococcus spp, 55.2%; Staphylococcus aureus, 27.6%; Escherichia coli, 6.9%; Streptococcus uberis, 6.9%; Corynebacterium bovis, 3.4%). Polymerase chain reaction-isolated the following genes linked to enro-C resistance: chromosomal (gyrA) and plasmid (aac(6')-lb-cr). The treatments were as follows: twice-daily intramammary infusions of enro-C (300 mg/10 mL) for 5 days. Cows clinically considered treatment failures were also treated with intramammary ceftiofur (125 mg/10 mL, twice daily for 5 days. The clinical and bacteriological cure rates were carried out when completing each treatment phase and at 14 and 21 days, aided by a California mastitis test, somatic cell count, and failure to identify the initially causative bacteria.

Results

Enro-C achieved 65% clinical and bacteriological cure rates, and 100% cure rates were obtained after the rescue treatment with ceftiofur HCl.

Conclusions

Outstanding clinical and bacteriological cure rates in cows affected by RScM were achieved with the consecutive intramammary infusions of enro-C, followed by ceftiofur HCl.

Pharmacokinetics, Pharmacodynamic Efficacy Prediction Indexes and Monte Carlo Simulations of Enrofloxacin Hydrochloride Against Bacterial Strains That Induce Common Clinical Diseases in Broiler Chickens

Pharmacokinetic parameters and efficacy prediction indexes (Cmax/MIC90 and AUC0-24/MIC90) of an enrofloxacin hydrochloride (ENR-HCl) veterinary product soluble in water were determined in healthy broiler chickens of both sexes after a single oral dose of ENR-HCl (equivalent to 10 mg ENR base/kg bw). Monte Carlo simulations targeting Cmax/MIC90 = 10 and AUC0-24/MIC90 =125 were also performed based on a set of MIC (minimum inhibitory concentration) values of bacterial strains that induce common clinical diseases in broiler chickens and that showed to be susceptible to ENR-HCl. Plasma concentrations of ENR and its main metabolite ciprofloxacin (CIP) were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Plasma concentration-time curves were found to fit a non-compartmental open model. The ratio of the area under the plasma concentration-time curve (AUC) of CIP/ENR was 4.91%. Maximum plasma concentrations of 1.35 ± 0.15 μg/mL for ENR-HCl and 0.09 ± 0.01 μg/mL for CIP were reached at 4.00 ± 0.00 h and 3.44 ± 1.01 h, respectively. Areas under the plasma vs. time concentration curve in 24 h (AUC0-24) were 18.91 ± 1.91 h × μg/mL and 1.19 ± 0.12 h × μg/mL for ENR-HCl and CIP, respectively. Using a microbroth dilution method, the minimum inhibitory concentration (MIC90) values were determined for ENR-HCl for 10 bacterial strains (Mycoplasma gallisepticum, Mycoplasma synoviae, Avibacterium paragallinarum, Clostridium perfringens, Escherichia coli, Pseudomonas aeruginosa, Salmonella ser. Enteritidis, Salmonella ser. Gallinarum, Salmonella ser. Pullorum, and Salmonella ser. Typhimurium), which are the most common causes of infectious clinical diseases in broiler chickens. In summary, the PK/PD ratios and Monte Carlo simulation were carried out for ENR-HCl in poultry, which due to its solubility was administered in drinking water. The PK/PD efficacy prediction indexes and Monte Carlo simulations indicated that the ENR-HCl oral dose used in this study is useful for bacterial infections in treating C. perfringens (Gram-positive), E. coli and S. ser. Enteritidis (Gram-negative) and M. gallisepticum bacteria responsible for systemic infections in poultry, predicting a success rate of 100% when MIC ≤ 0.06 μg/mL for E. coli and S. ser. Enteritidis and MIC ≤ 0.1 μg/mL for M. gallisepticum. For C. perfringens, the success rate was 98.26% for MIC ≤ 0.12. However, clinical trials are needed to confirm this recommendation.

Comparative bioavailability of enrofloxacin in dogs when concealed in noncommercial morsels, either as tablet or as enrofloxacin-alginate dried beads

Administration of enrofloxacin tablets concealed in improvised morsels to elude the unpleasant flavor of this drug is likely to diminish maximum plasma concentrations (C_max ) reached by this drug, jeopardizing treatment efficacy. To avoid this, the hypothesis that alginate dried beads containing enrofloxacin (ADBE) could modify the pharmacokinetics of enrofloxacin in dogs was tested. ADBE were manufactured and pharmaceutically defined as having high entrapment efficiency (>90%) and a drug loading capacity of 56%-67%. Based on the hydrophilic nature of alginate and its interaction with the anionic charge of the amino groups of enrofloxacin, a novel modified release system was obtained in which ADBE give place to both a rapid diffusion releasing of enrofloxacin and a maintained release. The ADBE concealed in a sausage (ADBEs) achieved both the highest Cmax (5.1 µg/ml ± 0.3 SD) and the area under the concentration versus time (AUC_0-24 ) (41.2 µg hr^-1  ml^-1  ± 6.9 SD). The tablet administered alone had a C_max of 1.9 µg/ml ± 0.3 SD and an AUC_0-24  = 16.5 µg h^-1  ml^-1  ± 3.5 SD, while the tablet concealed in a sausage reached a C_max of 1.2 µg/ml ± 0.3 SD with an AUC_0-24  = 12.3 µg hr^-1  ml^-1  ± 3.8 SD (p < .05 in both cases when confronting ADBEs vs. tablets). Consequently, C_max /MIC and AUC_0-24 /MIC ratios are higher for ADBEs. Other PK parameters were statistically indistinguishable, and other morsels containing enrofloxacin as a tablet or as ADBE rendered less favorable PK parameters. Due to ease of administration and favorable PK for ADBE concealed in a sausage, this pharmaceutical design can be regarded as PK/PD consistent and worthy of clinical studies.

Oral Plus Topical Administration of Enrofloxacin-Hydrochloride-Dihydrate for the Treatment of Unresponsive Canine Pyoderma. A Clinical Trial

An outpatient clinical trial on unresponsive deep-bacterial canine pyoderma (UDCP), without a control group, is presented. The chosen treatment was implemented with a new crystal-solvate of enrofloxacin (enrofloxacin HCl-2H2O or enro-C), in a dual scheme, i.e., 10 mg/kg/day PO, plus its topical administration, prepared as 0.5% in an alginate gel, thrice per day. Fifty-five cases that were unsuccessfully treated previously with another antibacterial drug, were selected and then classified as severe or very severe, according to a clinical score tailored for this trial. Aerobic bacteriological cultures of skin lesions and antibacterial sensitivity tests, were performed. Hematological status, liver, and kidney functions were determined before and after treatment. A complete success was obtained in 32 severe and 23 very severe, cases. The main bacterial isolates were: Staphylococcus intermedius (19/99), Staphylococcus pseudintermedius (16/99), Staphylococcus epidermidis (15/99), Staphylococcus pyogenes (14/99), Staphylococcus saprophyticus, Streptococcus sp., and others including Pseudomonas aeruginosa (6/99). The average duration of treatment was 8.03 days ± 2.1 SD and 12.0 ± 2.4 days, for dogs with severe or very severe UDCP, respectively. The adverse effects caused by enro-C were inconsequential and the hematological tests showed no deviations from normality. The use of enro-C administered dually to treat UDCP, is considered safe and highly effective.

Outpatient Clinical Trial in Dogs With Leptospirosis Treated With Enrofloxacin Hydrochloride-Dihydrate (ENRO-C)

Pharmacokinetics of enrofloxacin HCl-2H2O (enro-C) in dogs and Monte-Carlo simulations against Leptospira spp. prompted a clinical study to treat the clinically apparent phase of this disease. Leptospirosis was diagnosed by real-time PCR from blood, micro-agglutination titers (MAT), clinical signs and blood parameters of the liver and kidney. In order to determine the clinical ability of the participants to diagnose leptospirosis on the first exam and establish an early treatment to avoid excessive organ damage, patients were clinically classified as: high-risk or medium-risk. Forty-five dogs were included in this trial (from 2017 to early 2019). The treatment consisted of IM injections of a 5% aqueous enro-C suspension (10 mg/kg/day) for 10 days, and subsequently enro-C was administered orally for another 7 days in gelatin capsules. Thirty-four high-risk and 11 medium-risk dogs were treated, including 6 puppies (4 high-risk with ages between 6 to 10 months and 2 medium-risk dogs with an average age of 6 and 7 months). Other ages ranged from 1 to 5 years. Fifteen cases had a history of having received prior treatment with other antibiotics, including all puppies. The clinical diagnostic error was 13.5% (7/52 cases), and only one of the misdiagnosed dogs had been classified as a high-risk patient. Three to 5 days after finishing treatment with enro-C, 82.2% of the dogs were negative to real-time PCR from urine samples and 100% negativity was observed on day 30 after treatment, when antibody titrations dropped to 1:100-1:200. Based on the absence of clinical signs, real-time PCR, and MAT titers, all treated dogs were considered as successful treatments. Within 6-24 months of clinical follow-up, no relapses were recorded. Adverse effects were inconsequential. This study represents the first report of a successful treatment of canine leptospirosis using a fluoroquinolone, and due to its efficacy, it is suggested that enro-C be considered as a viable option for the treatment of this disease.

Pharmacokinetics of enrofloxacin HCl-2H2 O (ENRO-C), PK/PD, and Monte Carlo modeling vs. Leptospira spp. in cows

The pharmacokinetics, PK/PD ratios, and Monte Carlo modeling of enrofloxacin HCl-2H₂ O (Enro-C) and its reference preparation (Enro-R) were determined in cows. Fifty-four Jersey cows were randomly assigned to six groups receiving a single IM dose of 10, 15, or 20 mg/kg of Enro-C (Enro-C₁₀ , Enro-C₁₅ , Enro-C₂₀ ) or Enro-R. Serial serum samples were collected and enrofloxacin concentrations quantified. A composite set of minimum inhibitory concentrations (MIC) of Leptospira spp. was utilized to calculate PK/PD ratios: maximum serum concentration/MIC (C_max /MIC₉₀ ) and area under the serum vs. time concentration of enrofloxacin/MIC (AUC_0-24 /MIC₉₀ ). Monte Carlo simulations targeted C_max /MIC = 10 and AUC_0-24 /MIC = 125. Mean C_max obtained were 6.17 and 2.46 μg/ml; 8.75 and 3.54 μg/ml; and 13.89 and 4.25 μg/ml, respectively for Enro-C and Enro-R. C_max /MIC₉₀ ratios were 6.17 and 2.46, 8.75 and 3.54, and 13.89 and 4.25 for Enro-C and Enro-R, respectively. Monte Carlo simulations based on C_max /MIC₉₀  = 10 indicate that only Enro-C₁₅ and Enro-C₂₀ may be useful to treat leptospirosis in cows, predicting a success rate ≥95% when MIC₅₀  = 0.5 μg/ml, and ≥80% when MIC₉₀  = 1.0 μg/ml. Although Enro-C₁₅ and Enro-C₂₀ may be useful to treat leptospirosis in cattle, clinical trials are necessary to confirm this proposal.