Absorption
The absolute bioavailability
of meloxicam capsules was 89% following a single oral dose of 30 mg
compared with 30 mg IV bolus injection. Following single intravenous
doses, dose-proportional pharmacokinetics were shown in the range
of 5 mg to 60 mg. After multiple oral doses the pharmacokinetics of
meloxicam capsules were dose-proportional over the range of 7.5 mg
to 15 mg. Mean C
max was achieved within four
to five hours after a 7.5 mg meloxicam tablet was taken under fasted
conditions, indicating a prolonged drug absorption. With multiple
dosing, steady-state concentrations were reached by Day 5. A second
meloxicam concentration peak occurs around 12 to 14 hours post-dose
suggesting biliary recycling.
Meloxicam oral suspension doses of 7.5 mg/5
mL and 15 mg/10 mL have been found to be bioequivalent to meloxicam
7.5 mg and 15 mg capsules, respectively. Meloxicam capsules have been
shown to be bioequivalent to MOBIC tablets.
Table 4 Single Dose and Steady-State Pharmacokinetic
Parameters for Oral 7.5 mg and 15 mg Meloxicam (Mean and % CV)
1
1The parameter values in
the table are from various studies
2 not under high fat conditions
3 MOBIC tablets
4 V
z/f =Dose/(AUC•K
el)
|
| | | Steady State | Single Dose |
Pharmacokinetic
Parameters
(% CV)
| Healthy
male adults
(Fed)
2
| Elderly
males
(Fed)
2
| Elderly females (Fed)
2
| Renal
failure (Fasted) | Hepatic
insufficiency (Fasted) |
| | | 7.5
mg
3 tablets
| 15 mg
capsules | 15 mg capsules | 15 mg
capsules | 15 mg
capsules |
| N | 18 | 5 | 8 | 12 | 12 |
| C
max
| [µg/mL] | 1.05 (20) | 2.3 (59) | 3.2 (24) | 0.59 (36) | 0.84 (29) |
| t
max
| [h] | 4.9 (8) | 5 (12) | 6 (27) | 4 (65) | 10 (87) |
| t
1/2
| [h] | 20.1 (29) | 21 (34) | 24 (34) | 18 (46) | 16 (29) |
| CL/f | [mL/min] | 8.8 (29) | 9.9 (76) | 5.1 (22) | 19 (43) | 11 (44) |
| V
z/f
4
| [L] | 14.7 (32) | 15 (42) | 10 (30) | 26 (44) | 14 (29) |
Food and Antacid
Effects
Administration
of meloxicam capsules following a high fat breakfast (75 g of fat)
resulted in mean peak drug levels (i.e., C
max) being increased by approximately 22% while the extent of absorption
(AUC) was unchanged. The time to maximum concentration (T
max) was achieved between 5 and 6 hours. In comparison,
neither the AUC nor the C
max values for meloxicam
suspension were affected following a similar high fat meal, while
mean T
max values were increased to approximately
7 hours. No pharmacokinetic interaction was detected with concomitant
administration of antacids. Based on these results, MOBIC can be administered
without regard to timing of meals or concomitant administration of
antacids.
Distribution
The mean volume of distribution (Vss) of
meloxicam is approximately 10 L. Meloxicam is ~99.4% bound to human
plasma proteins (primarily albumin) within the therapeutic dose range.
The fraction of protein binding is independent of drug concentration,
over the clinically relevant concentration range, but decreases to
~99% in patients with renal disease. Meloxicam penetration into human
red blood cells, after oral dosing, is less than 10%. Following a
radiolabeled dose, over 90% of the radioactivity detected in the plasma
was present as unchanged meloxicam.
Meloxicam concentrations in synovial fluid,
after a single oral dose, range from 40% to 50% of those in plasma.
The free fraction in synovial fluid is 2.5 times higher than in plasma,
due to the lower albumin content in synovial fluid as compared to
plasma. The significance of this penetration is unknown.
Elimination
Metabolism
Meloxicam is extensively
metabolized in the liver. Meloxicam metabolites include 5'-carboxy
meloxicam (60% of dose), from P-450 mediated metabolism formed by
oxidation of an intermediate metabolite 5'‑hydroxymethyl meloxicam
which is also excreted to a lesser extent (9% of dose).
In
vitro studies indicate that CYP2C9 (cytochrome P450 metabolizing
enzyme) plays an important role in this metabolic pathway with a minor
contribution of the CYP3A4 isozyme. Patients’ peroxidase activity
is probably responsible for the other two metabolites which account
for 16% and 4% of the administered dose, respectively. All the four
metabolites are not known to have any
in vivo pharmacological
activity.
Excretion
Meloxicam excretion is predominantly in the form of metabolites,
and occurs to equal extents in the urine and feces. Only traces of
the unchanged parent compound are excreted in the urine (0.2%) and
feces (1.6%). The extent of the urinary excretion was confirmed for
unlabeled multiple 7.5 mg doses: 0.5%, 6%, and 13% of the dose were
found in urine in the form of meloxicam, and the 5'‑hydroxymethyl
and 5'‑carboxy metabolites, respectively. There is significant biliary
and/or enteral secretion of the drug. This was demonstrated when oral
administration of cholestyramine following a single IV dose of meloxicam
decreased the AUC of meloxicam by 50%.
The mean elimination half-life (t
1/2) ranges from 15 hours to 20 hours. The elimination
half-life is constant across dose levels indicating linear metabolism
within the therapeutic dose range. Plasma clearance ranges from 7
to 9 mL/min.
Specific Populations
Pediatric
After single (0.25 mg/kg) dose administration
and after achieving steady state (0.375 mg/kg/day), there was a general
trend of approximately 30% lower exposure in younger patients (2 to
6 years old) as compared to the older patients (7 to 16 years old).
The older patients had meloxicam exposures similar (single dose) or
slightly reduced (steady state) to those in the adult patients, when
using AUC values normalized to a dose of 0.25 mg/kg [
see Dosage
and Administration (
2.4)
]. The meloxicam mean (SD) elimination half-life was 15.2 (10.1)
and 13.0 hours (3.0) for the 2 to 6 year old patients, and 7 to 16
year old patients, respectively.
In a covariate analysis, utilizing population
pharmacokinetics body-weight, but not age, was the single predictive
covariate for differences in the meloxicam apparent oral plasma clearance.
The body-weight normalized apparent oral clearance values were adequate
predictors of meloxicam exposure in pediatric patients.
The pharmacokinetics of MOBIC
in pediatric patients under 2 years of age have not been investigated.
Geriatric
Elderly males (≥65 years of
age) exhibited meloxicam plasma concentrations and steady-state pharmacokinetics
similar to young males. Elderly females (≥65 years of age) had a 47%
higher AUC
ss and 32% higher C
max,ss as compared to younger females (≤55 years of age) after body weight
normalization. Despite the increased total concentrations in the elderly
females, the adverse event profile was comparable for both elderly
patient populations. A smaller free fraction was found in elderly
female patients in comparison to elderly male patients.
Sex
Young females exhibited slightly
lower plasma concentrations relative to young males. After single
doses of 7.5 mg MOBIC, the mean elimination half-life was 19.5 hours
for the female group as compared to 23.4 hours for the male group.
At steady state, the data were similar (17.9 hours vs 21.4 hours).
This pharmacokinetic difference due to gender is likely to be of little
clinical importance. There was linearity of pharmacokinetics and no
appreciable difference in the C
max or T
max across genders.
Hepatic Impairment
Following a single 15 mg dose
of meloxicam there was no marked difference in plasma concentrations
in patients with mild (Child-Pugh Class I) or moderate (Child-Pugh
Class II) hepatic impairment compared to healthy volunteers. Protein
binding of meloxicam was not affected by hepatic impairment. No dosage
adjustment is necessary in patients with mild to moderate hepatic
impairment. Patients with severe hepatic impairment (Child-Pugh Class
III) have not been adequately studied [
see Warnings and Precautions
(
5.3) and Use in Specific Populations
(
8.6)
].
Renal Impairment
Meloxicam pharmacokinetics have
been investigated in subjects with mild and moderate renal impairment.
Total drug plasma concentrations of meloxicam decreased and total
clearance of meloxicam increased with the degree of renal impairment
while free AUC values were similar in all groups. The higher meloxicam
clearance in subjects with renal impairment may be due to increased
fraction of unbound meloxicam which is available for hepatic metabolism
and subsequent excretion. No dosage adjustment is necessary in patients
with mild to moderate renal impairment. Patients with severe renal
impairment have not been adequately studied. The use of MOBIC in subjects
with severe renal impairment is not recommended [
see Dosage
and Administration (
2.5), Warnings
and Precautions (
5.6) and Use in
Specific Populations (
8.7)
].
Hemodialysis
Following a single
dose of meloxicam, the free C
max plasma concentrations
were higher in patients with renal failure on chronic hemodialysis
(1% free fraction) in comparison to healthy volunteers (0.3% free
fraction). Hemodialysis did not lower the total drug concentration
in plasma; therefore, additional doses are not necessary after hemodialysis.
Meloxicam is not dialyzable [
see Dosage and Administration
(
2.1) and Use in Specific Populations
(
8.7)
].
Drug Interaction Studies
Aspirin: When NSAIDs were administered with aspirin, the protein binding
of NSAIDs were reduced, although the clearance of free NSAID was not
altered. When MOBIC is administered with aspirin (1000 mg three times
daily) to healthy volunteers, it tended to increase the AUC (10%)
and C
max (24%) of meloxicam. The clinical significance
of this interaction is not known. See Table 3 for clinically significant
drug interactions of NSAIDs with aspirin [
see Drug Interactions
(
7)
].
Cholestyramine: Pretreatment
for four days with cholestyramine significantly increased the clearance
of meloxicam by 50%. This resulted in a decrease in t
1/2, from 19.2 hours to 12.5 hours, and a 35% reduction in AUC. This
suggests the existence of a recirculation pathway for meloxicam in
the gastrointestinal tract. The clinical relevance of this interaction
has not been established.
Cimetidine: Concomitant
administration of 200 mg cimetidine four times daily did not alter
the single-dose pharmacokinetics of 30 mg meloxicam.
Digoxin: Meloxicam 15 mg
once daily for 7 days did not alter the plasma concentration profile
of digoxin after β-acetyldigoxin administration for 7 days at clinical
doses.
In vitro testing found no protein binding
drug interaction between digoxin and meloxicam.
Lithium: In a study conducted
in healthy subjects, mean pre-dose lithium concentration and AUC were
increased by 21% in subjects receiving lithium doses ranging from
804 to 1072 mg twice daily with meloxicam 15 mg QD every day as compared
to subjects receiving lithium alone [
see Drug Interactions
(
7)
].
Methotrexate: A study in
13 rheumatoid arthritis (RA) patients evaluated the effects of multiple
doses of meloxicam on the pharmacokinetics of methotrexate taken once
weekly. Meloxicam did not have a significant effect on the pharmacokinetics
of single doses of methotrexate.
In vitro, methotrexate
did not displace meloxicam from its human serum binding sites [
see Drug Interactions (
7)
].
Warfarin: The effect of meloxicam on the anticoagulant effect of warfarin
was studied in a group of healthy subjects receiving daily doses of
warfarin that produced an INR (International Normalized Ratio) between
1.2 and 1.8. In these subjects, meloxicam did not alter warfarin pharmacokinetics
and the average anticoagulant effect of warfarin as determined by
prothrombin time. However, one subject showed an increase in INR from
1.5 to 2.1. Caution should be used when administering MOBIC with warfarin
since patients on warfarin may experience changes in INR and an increased
risk of bleeding complications when a new medication is introduced
[
see Drug Interactions (
7)
].