Biology Reference
In-Depth Information
17.3 Results
A few minutes after tramadol IV administration, one of the subjects had an epileptic
crisis that lasted 3 min. When the same dose was administered slowly (within
2 min), only mild sedation and tremors lasting less than 30 min were present in all
animals. No adverse effects were noted after IM administration of the same dose of
drug.
The plasma concentrations/time curves of tramadol after IV and IM administra-
tion are reported in Fig.
17.1
. A noncompartmental model fitted the plasma
concentrations of tramadol. The elimination half-life, the volume of distribution,
and the systemic clearance of tramadol were 1.20
0.61 and 0.78
0.25 h,
3.42
0.39 L/h/kg,
following IV and IM administration, respectively. These values were significantly
different
2.36 and 1.54
0.54 L/kg, and 2.15
0.35 and 1.29
0.05) between groups. The mean systemic bioavailability of
tramadol administered IM was 81.5
(
P
<
14.3% with a range of values between 75
and 96%. After IM administration, the time taken to reach the minimal effective
concentration (MEC)
t
e
, and the period of time during which this plasma concen-
tration was exceeded,
D
t
e
, were 1.0
0.2 min and 2.5
0.35 h, respectively.
Following IV administration,
0.30 h. The M2 metabolite had
similar plasma concentration/time curves after both administrations, and it was
detectable from 5 min to 4 and 6 h after IV and IM treatment, respectively. By
contrast, M1 and M5 were detected in one and two alpacas, respectively. These
metabolites were detected at concentrations close to the limit of quantification
(LOQ) for the method (0.005
D
t
e
was 3.15
m
g/mL). Therefore, their pharmacokinetic parameters
10000
1000
MEC (Malone et al., 2004)
100
10
0
2
4
6
Time (hours)
Fig. 17.1 Plasma concentrations/time curves of tramadol following IV (
open circle
) and IM
(
closed circle
) administration
