The pharmacokinetic profile of marbofloxacin has been extensively studied and investigated in different species of birds
viz., in broiler chickens
(Atef et al., 2017; Patel et al., 2018), Japanese quails (
Aboubakr and Abdelazem, 2015), bilgorajska geese (
Anser anser domesticus)
(Sartini et al., 2020); ostriches (
De Lucas et al., 2005) and blue-gold macaws
(Carpenter et al., 2006). The effects of lactic acid pre-treatment on pharmacokinetics of enrofloxacin in Chinese mitten crab (
Eriocheir sinensis)
(Su et al., 2019) and effects of
Lactobacillus acidophilus on pharmacokinetics of marbofloxacin in rats
(Birhanu et al., 2017) were reported. However, no similar studies involving lactic acid pre-treatment in broiler chickens and its impact on pharmacokinetics of marbofloxacin have been reported.
The present study on effects of feeding lactic acid on pharmacokinetics of marbofloxacin in broiler chickens stands unique with respect to explore the paucity of scientific data reflecting alteration of pharmacokinetics of marbofloxacin by lactic acid pre-treatment in broilers. The outcome of the present investigation provides a great insight to clinician while treating diseases in lactic acid pre-treated poultry using marbofloxacin.
The semi-logarithmic plots of marbofloxacin plasma concentrations following single dose (5 mg/kg body weight) oral administration in without pre-treated lactic acid and with pre-treated lactic acid (8.0 mg/kg each, PO, for 10 days) broiler chickens are depicted in Fig 2.
The values of plasma concentrations of marbofloxacin at each time point were statistically analysed using a student’s t-test for the test of significant difference between groups 1 and 2 of birds (with or without lactic acid pre-treatment). The lactic acid pre-treatment caused significant differences in the values of plasma concentrations of marbofloxacin at 0.5 and 1 h. Decreased concentrations of marbofloxacin in the plasma of pre-treated birds (0.65±0.06 at 0.5 h and 0.85±0.05 at 1 h) were observed as compared to those observed in the plasma of birds of the control group
i.e., without pre-treatment (1.09±0.09 at 0.5 h and 2.11±0.37 at 1 h) (Table 1).
Highly significant differences (p≤0.01) between group of birds without pre-treatment and with pre-treatment of lactic acid were found in the concentrations of time points of 0.5 h (1.09±0.09 v/s 0.65±0.06) and 1 h (2.11±0.37 v/s 0.85±0.05), while a non-significant difference (p≥0.05) was found in the concentrations of the remaining time points (0.25 h, 2 h, 4 h, 8 h and 12 h) (Table 2). The values of PK parameters that showed a significant difference (p≤0.05) between with pre-treatment of lactic acid and without a pre-treatment of lactic acid group were elimination half-life, area under curve (AUC), area under moment curve (AUMC) and mean residence time (MRT) whereas, highly significant difference (p≤0.01) was seen in the values of maximum concentration (C
max) and the remaining PK parameters showed non-significant differences (p≥0.05) statistically (Table 2).
The mean value of elimination half-life (t
½β) after single dose oral administration of marbofloxacin (5 mg/kg) in pre-treated broiler chickens was found as 2.81 h in present study. This value was found to be significantly lower (p≤0.05) than the value reported in birds without pre-treatment after single oral administration of marbofloxacin (4.89 h). Similar scenario in the values of elimination half-life was also observed by
Birhanu et al., (2017) in a study conducted in rats, where the elimination half-lives of marbofloxacin before and after treatment with
L. acidophilus in rats were also reported as 1.19 h and 0.69 h, respectively. The mean value of AUC was 6.16±1.34 μg
·h/mL after single dose oral administration of marbofloxacin (5 mg/kg) in pre-treated broiler chickens (Group-2), which was significantly lower (p≤0.05) than the value of AUC (14.70±2.94 μg
·h/mL) observed in birds without pre-treatment (Group-1). This showed low exposure of the body to the drug, when lactic acid was used as pre-treatment in broiler chickens. Significantly higher (p≤0.05) value of ClB was observed in birds of lactic acid pre-treatment group (1.03 L/h/kg; Group-2) as compared to the value observed in birds without pre-treatment (0.47 L/h/kg; Group-1;). Present findings suggest that lactic acid accelerates clearance rate of marbofloxacin from body of broiler chickens.
In present study, the elimination rate constant (β) calculated after single dose oral administration of marbofloxacin (5 mg/kg) in pre-treated broiler chickens (Group-2) was 0.31 h
-1, which was significantly higher (p≤0.05) than value of β (0.17 h
-1) observed in birds without pre-treatment (Group-1). The decreased values of elimination half-life and increased value of total body clearance in pre-treated birds indicates comparatively faster elimination from body, which is evident with comparatively lower values of MRT( 4.73 v/s 7.48 h) in pre-treated birds. This may be due to changes in physiological environment of body organs involved in processing of drugs
viz., liver, kidney, gastrointestinal tract. The lactic acid acts as an acidifier and is likely to bring significant changes in the ADME of marbofloxacin. Marbofloxacin metabolism is a typical CYP450 reaction involving the oxidation of NADPH, it can be speculated that lactic acid may directly influence the TCA cycle to generate sufficient metabolic enzyme (CYP450 enzyme and GST) to influence the pharmacokinetics of marbofloxacin as observed for enrofloxacin
(Su et al., 2019). This is similar to the view that lactic acid is a primary circulating TCA substrate in most mammalian tissues
(Hui et al., 2017). In short, lactic acid may influence the rate of marbofloxacin elimination by enhancing the biotransformation activity of the hepato-pancreas and induce the activity of microsomal enzymes.
The activity of drug metabolizing enzymes including Phase I and Phase II of biotransformation is key factor determining the pharmacokinetic profiles of the drug.
The CYP2 and CYP3 subfamilies have important roles in xenobiotic metabolism
(Ren et al., 2017). The possible pharmacokinetic alterations due to enzyme induction depend on the localisation of the enzyme. Theses alteration occur via lowered or no bioavailability for orally administered drugs, increased hepatic metabolism or accelerated formation of reactive metabolites (
Fuhr, 2000).
The reports of impact of lactic acid on pharmacokinetics of marbofloxacin in broilers are not available, however
Su et al., (2019) studied the effects of LA on drug residues and elimination of oral another fluoroquinolone (enrofloxacin) in Chinese mitten crab (Eriocheir sinensis) with gene expression levels of drug-metabolizing enzymes in the hepatopancreas. Significant differences were observed in the pharmacokinetic profile of enrofloxacin along with no effects on the expression of CYP2A (phase I) and significant up regulation of CYP3 (phase I) and GST (phase II). The results provided evidences that LA contributed to comparatively faster elimination of drug, and thus, enhances hepatopancreas and biotransformation.
The mean apparent volume of distribution (Vd
(area)) following single dose oral administration of marbofloxacin (5 mg/kg) in pre-treated broiler chickens was calculated to be 3.50 L/kg. The value was more than the value reported for marbofloxacin alone after single oral administration (2.80 L/kg). There was no statistical significance observed for difference. The time required for an intact drug molecule to transit through body is termed as mean residence time (MRT). Thus, MRT becomes an important parameter to describe the length of drug persistence in the body. Statistically significant lower (p≤0.05) value of MRT was observed in lactic acid pre-treatment (4.73 h; Group-2) as compared to without pre-treatment (7.48 h; Group -1).