الفهرس 
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Abstract
The pharmacokinetics of levofloxacin was studied on 15
female lactating goats (10 normal and 5 experimentally
Escherichia coli infected goats). Goats were divided into 3 groups
each one included 5 goats. The pharmacokinetics and
bioavailability levofloxacin were calculated in normal goats after
a single intravenous and intramuscular dose. The drug clearance,
urine output and retaining clearance were investigated in normal
and experimentally Escherichia coli infected goats following
intramuscular administrations of 4 mg levofloxacin /kg.b.wt.
twice daily for five consecutive days. The in vitro protein binding
percent of levofloxacin was determined microbiologically.
Following a single intravenous injection of 4 mg
levofloxacin /kg.b.wt. in normal goats, levofloxacin could be
detected for 12 hours post intravenous dose with value equal to
0.032±0.004 ug/ml. the serum concentration-time curve of
levofloxacin following intravenous injection showed that the
drug obeyed a two-compartments open model. This observation
indicated that the body was viewed as consisting of two -
compartments: a central co mpartment of plasma and rapid
equilibrating tissues, and a deeper slower equilibrating
compartment (skin and connective tissues). Levofloxacin after
intravenous dose revealed a rapid distribution phase [α] equal to
4.08 ± 0.06 h-1 with a distribution half-life [t0.5(α)] equal to 0.17 ± 0.003
h. The volume of distribution of levofloxacin to the central compartment
[V1
c] was 558.69±28.62 ml/kg., whereas the calculated body
distribution by
extrapolation [Vd(B)], area [Vd(area)] and steady -state [Vdss] methods were
924.62±15.10, 878.82±17.21 and 854.81±35.65 ml/kg respectively.
Levofloxacin was transferred from central to peripheral
compartment [K12] at slower rate 1.65 ± 0.05 h-1 than its passage
from peripheral to central compartment [K21] equal to 2.46 ± 0.05 h-1.
Levofloxacin was eliminated after intravenous injection with a
half-life [t0.5(β)] value of 1.53 ± 0.05 h and cleared by all clearance
processes in the body at a rate of 3.39 ± 0.06 ml/kg/min.
Following a single intramuscular injection o f 4 mg
levofloxacin /kg.b.wt. in normal goats, the drug reached its
maximum serum concentrations after 1hour of injection with
value equal to 3.13 ± 0.03 ug/ml Levofloxacin could be detected for
12 hours post intramuscular dose with value equal to 0.12± 0.006
ug/ml. The absorption half life [t0.5(ab)] was 0.30 ± 0.003 h.
Apparent elimination half-life [t0.5(β)] was 2.27 ± 0.06 h and
levofloxacin was cleared by all clearance processes [Cltot] with
rate equal to 4.82 ± 0.06 ml/kg/min.
The mean systemic bioavailability of levofloxacin
following a single intramuscular injection in normal goats was
93.38±0.54 %; this value referred a better absorption of
levofloxacin from its site of intramuscular administration.
The serum concentrations of levofloxacin in normal and
experimentally Escherichia coli infected goats following repeated
intramuscular injections of 4 mg/kg. b.wt. twice daily for five
consecutive days, peaked 1 hour after each intramuscular dose
with a lower significant values recorded in experimentally
Escherichia coli infected goats than in normal goats. This
observation might be attributed to the higher penetrating power
of the drug to diseased tissues.
The apparent first order absorption rate constants [Kab] are
significantly lower in Es c he r ic hia co l i infected goats than in normal
goats following 1st, 3rd, 7th and 9th doses.
The results illustrated a significant decrease in the maximum serum
concentrations [Cmax] in Es c he r ic hia c o li infected goats than in normal
goats following all doses., while absorption half lives [t0.5(ab)] are
significantly higher in Es c he r ic hia co li infected goats than in normal
goats following 1st, 3rd, 7th and 9th doses. The elimination half lives [t0.5(β)]
are significantly lower in Es c her ic hia c o li infected goats than in normal
goats following all doses.
Levofloxacin is cleared by all clearance processes [Cltot] in the body
at faster significant rates in Es c he r ic hia co li infected goats than in
normal goats.
The mean peak urine concentrations of levofloxacin are
reached 1.