CLINICAL PHARMACOLOGY
Mechanism Of Action
Rofecoxib has analgesic,
anti-inflammatory, and antipyretic properties.
The mechanism of action of
VIOXX, like that of other NSAIDs, is not completely understood, but involves
inhibition of cyclooxygenase (COX-1 and COX-2). At therapeutic concentrations
in humans, VIOXX does not inhibit the cyclooxygenase-1 (COX-1) isoenzyme.
Rofecoxib is a potent inhibitor of prostaglandin
synthesis in vitro. Rofecoxib concentrations reached during therapy have
produced in vivo effects. Prostaglandins sensitize afferent nerves and
potentiate the action of bradykinin in inducing pain in animal models.
Prostaglandins are mediators of inflammation. Because rofecoxib is an inhibitor
of prostaglandin synthesis, its mode of action may be due to a decrease of
prostaglandins in peripheral tissues.
Studies to elucidate the mechanism of action of VIOXX in
the acute treatment of migraine have not been conducted.
Pharmacokinetics
Absorption
The mean oral bioavailability of VIOXX at therapeutically
recommended doses of 12.5, 25, and 50 mg is approximately 93%. The area under
the curve (AUC) and peak plasma level (Cmax) following a single 25-mg dose were
3286 (±843) ng•hr/mL and 207 (±111) ng/mL, respectively. Both Cmax and AUC are
roughly dose proportional across the clinical dose range. At doses greater than
50 mg, there is a less than proportional increase in Cmax and AUC, which is
thought to be due to the low solubility of the drug in aqueous media. The
plasma concentration-time profile exhibited multiple peaks. The median time to
maximal concentration (Tmax), as assessed in nine pharmacokinetic studies, is 2
to 3 hours. Individual Tmax values in these studies ranged between 2 to 9
hours. This may not reflect rate of absorption as Tmax may occur as a secondary
peak in some individuals. With multiple dosing, steady-state conditions are
reached by Day 4. The AUC0-24hr and Cmax at steady state after multiple doses
of 25 mg rofecoxib was 4018 (±1140) ng•hr/mL and 321 (±104) ng/mL, respectively,
in healthy adults. The accumulation factor based on geometric means was 1.67.
The AUC0-24hr and Cmax at steady state after multiple doses of 25 mg rofecoxib
was 6934 (±2158) ng•hr/mL and 519 (±163) ng/mL, respectively, in adult RA
patients (N=12, mean body weight 62 kg).
VIOXX Tablets 12.5 mg and 25 mg are bioequivalent to
VIOXX Oral Suspension 12.5 mg/5 mL and 25 mg/5 mL, respectively.
Food And Antacid Effects
Food had no significant effect on either the peak plasma
concentration (Cmax) or extent of absorption (AUC) of rofecoxib when VIOXX
Tablets were taken with a high fat meal. The time to peak plasma concentration
(Tmax), however, was delayed by 1 to 2 hours. The food effect on the suspension
formulation has not been studied. VIOXX tablets can be administered without
regard to timing of meals.
There was a 13% and 8% decrease in AUC when VIOXX was
administered with calcium carbonate antacid and magnesium/aluminum antacid to
elderly subjects, respectively. There was an approximate 20% decrease in Cmax
of rofecoxib with either antacid (see PRECAUTIONS: DRUG INTERACTIONS).
Distribution
Rofecoxib is approximately 87% bound to human plasma
protein over the range of concentrations of 0.05 to 25 mcg/mL. The apparent
volume of distribution at steady state (Vdss) is approximately 91 L following a 12.5-mg dose and 86 L
following a 25-mg dose.
Rofecoxib has been shown to cross the placenta in rats
and rabbits, and the blood-brain barrier in rats.
Elimination
Metabolism
Metabolism of rofecoxib is primarily mediated through
reduction by cytosolic enzymes. The principal metabolic products are the
cis-dihydro and trans-dihydro derivatives of rofecoxib, which account for
nearly 56% of recovered radioactivity in the urine. An additional 8.8% of the
dose was recovered as the glucuronide of the hydroxy derivative, a product of
oxidative metabolism. The biotransformation of rofecoxib and this metabolite is
reversible in humans to a limited extent ( < 5%). These metabolites are
inactive as COX-1 or COX-2 inhibitors.
Cytochrome P450 plays a minor role in metabolism of
rofecoxib. Inhibition of CYP 3A activity by administration of ketoconazole 400
mg daily does not affect rofecoxib disposition. However, induction of general
hepatic metabolic activity by administration of the non-specific inducer
rifampin 600 mg daily produces a 50% decrease in rofecoxib plasma
concentrations (see PRECAUTIONS: DRUG INTERACTIONS).
Excretion
Rofecoxib is eliminated predominantly by hepatic
metabolism with little ( < 1%) unchanged drug recovered in the urine.
Following a single radiolabeled dose of 125 mg, approximately 72% of the dose
was excreted into the urine as metabolites and 14% in the feces as unchanged
drug.
The plasma clearance after 12.5- and 25-mg doses was
approximately 141 and 120 mL/min, respectively. Higher plasma clearance was
observed at doses below the therapeutic range, suggesting the presence of a
saturable route of metabolism (i.e., non-linear elimination). The effective half-life
(based on steady-state levels) was approximately 17 hours.
Special Populations
Sex
The pharmacokinetics of rofecoxib are comparable in men
and women.
Geriatric
After a single dose of 25 mg VIOXX in elderly subjects
(over 65 years old) a 34% increase in AUC was observed as compared to the young
subjects. Dosage adjustment in the elderly is not necessary; however, therapy
with VIOXX should be initiated at the lowest recommended dose.
Pediatric
The steady state pharmacokinetics of rofecoxib was
evaluated in patients ≥ 2 years to ≤ 17 years of age who weigh
more than 10 kg with pauciarticular and polyarticular course Juvenile
Rheumatoid Arthritis (JRA). The apparent clearance after oral administration of
rofecoxib in patients ≥ 12 years to ≤ 17 years of age was similar
to that of healthy adults and higher than that of adult RA patients. The
apparent clearance after oral administration of rofecoxib in patients ≥
2 years to ≤ 11 years of age was less than that of adults and increased
with age. The apparent oral clearance of rofecoxib increases with body weight
(and body surface area). (See Table 1.)
Table 1 : Rofecoxib Apparent Oral Clearance (CL/F,
mean ± SD) in JRA Patients* and Adults.
Group |
JRA patients |
Adults |
2- to 5-year-old
(N=21) |
6- to 11-year-old
(N=13) |
12- to 17- year-old
(N=11) |
Healthy Age range: 20-48
(N=26) |
RA Patients Age range: 31-64
(N=12) |
Body Weight (kg) (mean ± SD) |
17 ± 2 |
29 ± 6 |
57 ± 13 |
77 ± 13 |
62 ± 11 |
CL/F (mL/min) |
37 ± 15 |
52 ± 13 |
87 ± 21 |
96 ± 30 |
65 ± 20 |
* Pauciarticular and
Polyarticular Course JRA |
A dose of 0.6 mg/kg to a
maximum of 25 mg once daily in patients ≥
2 years to ≤ 11 years of age and body
weight 10 kg or above and a dose of 25 mg once daily in patients ≥ 12 years to ≤ 17 years of age would yield
an AUC slightly higher than that of the 25-mg tablet once daily in healthy
adults (AUC Geometric Mean Ratio, 1.12) and slightly
lower than that in adult RA patients (AUC GMR, 0.77).
Race
Meta-analysis of
pharmacokinetic studies has suggested a slightly (10-15%) higher AUC of
rofecoxib in Blacks and Hispanics as compared to Caucasians. No dosage
adjustment is necessary on the basis of race.
Hepatic Impairment
A single-dose pharmacokinetic study in mild (Child-Pugh
score ≤ 6) hepatic insufficiency patients indicated that rofecoxib AUC
was similar between these patients and healthy subjects. A pharmacokinetic
study in patients with moderate (Child-Pugh score 7-9) hepatic insufficiency
indicated that mean rofecoxib plasma concentrations were higher (mean AUC: 55%;
mean Cmax: 53%) relative to healthy subjects. Since patients with hepatic
insufficiency are prone to fluid retention and hemodynamic compromise, the
maximum recommended chronic dose of VIOXX for patients with moderate hepatic
insufficiency is 12.5 mg daily. (see WARNINGS; Hepatotoxicity, DOSAGE
AND ADMINISTRATION; Hepatic Insufficiency). Patients with severe
hepatic insufficiency have not been studied. Therefore, Vioxx should not be
used in patients with severe hepatic insufficiency.
Renal Impairment
In a study (N=6) of patients with end stage renal disease
undergoing dialysis, peak rofecoxib plasma levels and AUC declined 18% and 9%,
respectively, when dialysis occurred four hours after dosing. When dialysis
occurred 48 hours after dosing, the elimination profile of rofecoxib was
unchanged. While renal insufficiency does not influence the pharmacokinetics of
rofecoxib, use of VIOXX in advanced renal disease is not recommended. (see WARNINGS;
Renal Toxicity and Hyperkalemia).
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. The clinical significance of this interaction is not known. See Table
6 for clinically significant drug interactions of NSAIDs with aspirin. (See
PRECAUTIONS: DRUG INTERACTIONS).
Methotrexate
VIOXX 12.5, 25, and 50 mg, each dose administered once
daily for 7 days, had no effect on the plasma concentration of methotrexate as
measured by AUC0-24hr in patients receiving single weekly methotrexate doses of
7.5 to 20 mg for rheumatoid arthritis. At higher than recommended doses, VIOXX
75 mg administered once daily for 10 days increased plasma concentrations by
23% as measured by AUC0-24hr in patients receiving methotrexate 7.5 to 15
mg/week for rheumatoid arthritis. At 24 hours postdose, a similar proportion of
patients treated with methotrexate alone (94%) and subsequently treated with
methotrexate co-administered with 75 mg of rofecoxib (88%) had methotrexate
plasma concentrations below the measurable limit (5 ng/mL) (see PRECAUTIONS: DRUG INTERACTIONS)
Cimetidine
Co-administration with high doses of cimetidine (800 mg
twice daily) increased the Cmax of rofecoxib by 21%, the AUC0-120hr by 23% and
the t½ by 15% (see PRECAUTIONS; DRUG INTERACTIONS).
General
In human studies the potential for rofecoxib to inhibit
or induce CYP 3A4 activity was investigated in studies using the intravenous
erythromycin breath test and the oral midazolam test. No significant difference
in erythromycin demethylation was observed with rofecoxib (75 mg daily)
compared to placebo, indicating no induction of hepatic CYP 3A4. A 30%
reduction of the AUC of midazolam was observed with rofecoxib (25 mg daily).
This reduction is most likely due to increased first pass metabolism through
induction of intestinal CYP 3A4 by rofecoxib. In vitro studies in rat
hepatocytes also suggest that rofecoxib might be a mild inducer for CYP 3A4.
Drug interaction studies with the recommended doses of
rofecoxib have identified potentially significant interactions with rifampin,
theophylline, and warfarin. Patients receiving these agents with VIOXX should
be appropriately monitored. Drug interaction studies do not support the
potential for clinically important interactions between antacids or cimetidine
with rofecoxib. Similar to experience with other nonsteroidal anti-inflammatory
drugs (NSAIDs), studies with rofecoxib suggest the potential for interaction
with ACE inhibitors. The effects of rofecoxib on the pharmacokinetics and/or
pharmacodynamics of ketoconazole, prednisone/prednisolone, oral contraceptives,
and digoxin have been studied in vivo and clinically important interactions
have not been found.
Clinical Studies
Adults
Osteoarthritis (OA)
VIOXX has demonstrated significant reduction in joint
pain compared to placebo. VIOXX was evaluated for the treatment of the signs
and symptoms of OA of the knee and hip in placebo- and active-controlled
clinical trials of 6 to 86 weeks duration that enrolled approximately 3900
patients. In patients with OA, treatment with VIOXX 12.5 mg and 25 mg once
daily resulted in improvement in patient and physician global assessments and
in the WOMAC (Western Ontario and McMaster Universities) osteoarthritis questionnaire,
including pain, stiffness, and functional measures of OA. In six studies of
pain accompanying OA flare, VIOXX provided a significant reduction in pain at
the first determination (after one week in one study, after two weeks in the
remaining five studies); this continued for the duration of the studies. In all
OA clinical studies, once daily treatment in the morning with VIOXX 12.5 and 25
mg was associated with a significant reduction in joint stiffness upon first
awakening in the morning. At doses of 12.5 and 25 mg, the effectiveness of
VIOXX was shown to be comparable to ibuprofen 800 mg TID and diclofenac 50 mg
TID for treatment of the signs and symptoms of OA. The ibuprofen studies were
6-week studies; the diclofenac studies were 12-month studies in which patients
could receive additional arthritis medication during the last 6 months.
Rheumatoid Arthritis (RA)
VIOXX has demonstrated significant reduction of joint
tenderness/pain and joint swelling compared to placebo. VIOXX was evaluated for
the treatment of the signs and symptoms of RA in two 12-week placebo- and
active-controlled clinical trials that enrolled a total of approximately 2,000
patients. VIOXX was shown to be superior to placebo on all primary endpoints
(number of tender joints, number of swollen joints, patient and physician
global assessments of disease activity). In addition, VIOXX was shown to be
superior to placebo using the American College of Rheumatology 20% (ACR20)
Responder Index, a composite of clinical, laboratory, and functional measures
of RA. VIOXX 25 mg once daily and naproxen 500 mg twice daily showed generally
similar effects in the treatment of RA. A 50-mg dose once daily of VIOXX was
also studied; however, no additional efficacy was seen compared to the 25-mg
dose.
Analgesia, including Dysmenorrhea
In acute analgesic models of post-operative dental pain,
post-orthopedic surgical pain, and primary dysmenorrhea, VIOXX relieved pain
that was rated by patients as moderate to severe. The analgesic effect
(including onset of action) of a single 50-mg dose of VIOXX was generally
similar to 550 mg of naproxen sodium or 400 mg of ibuprofen. In single-dose
post-operative dental pain studies, the onset of analgesia with a single 50-mg
dose of VIOXX occurred within 45 minutes. In a multiple-dose study of
post-orthopedic surgical pain in which patients received VIOXX or placebo for
up to 5 days, 50 mg of VIOXX once daily was effective in reducing pain. In this
study, patients on VIOXX consumed a significantly smaller amount of additional
analgesic medication than patients treated with placebo (1.5 versus 2.5 doses
per day of additional analgesic medication for VIOXX and placebo,
respectively).
Migraine With or Without Aura
The efficacy of VIOXX in the acute treatment of migraine headaches
was demonstrated in two double-blind, placebo-controlled, outpatient trials.
Doses of 25 and 50 mg were compared to placebo in the treatment of one migraine
attack. A second dose of VIOXX was not allowed in either trial. In these
controlled short-term studies, patients were predominantly female (88%) and
Caucasian (84%), with a mean age of 40 years (range 18 to 78). Patients were
instructed to treat a moderate to severe headache. Headache relief, defined as
a reduction in headache severity from moderate or severe pain to mild or no
pain, was assessed up to 2 hours after dosing. Associated symptoms such as
nausea, photophobia, and phonophobia were also assessed. Maintenance of relief
was assessed for up to 24 hours postdose. Other medication, with the exception
of NSAIDs (including COX-2 inhibitors) or combination medications that
contained NSAIDs, was permitted from 2 hours after the dose of study
medication. The frequency and time to use of additional medications were also
recorded.
In both placebo-controlled trials, the percentage of
patients achieving headache relief 2 hours after treatment was significantly
greater among patients receiving VIOXX at all doses compared to those who
received placebo (Table 2). There were no statistically significant differences
between the 25- and the 50mg dose groups in either trial.
Table 2 : Percentage of Patients with Headache Relief
(Mild or No Headache) 2 hours Following Treatment
Trial |
VIOXX 25 mq |
VIOXX 50 mq |
Placebo |
1 |
54%* (n=176) |
57%* (n=187) |
34% (n=175) |
2 |
60%* (n=187) |
62%* (n=188) |
30% (n=187) |
*p < 0.0001 vs. placebo |
Note that, in general,
comparisons of results obtained in different clinical studies conducted under
different conditions by different investigators with different samples of
patients are ordinarily unreliable for purposes of quantitative comparison.
The estimated probability of
achieving initial headache relief within 2 hours following treatment is
depicted in Figure 1.
Figure 1 : Estimated
Probability of Achieving Initial Headache Relief within 2 Hours
Figure 1 shows the Kaplan-Meier
plot of the probability over time of obtaining headache relief (no or mild
pain) following treatment with VIOXX or placebo. The plot is based on pooled
data from the 2 placebo-controlled, outpatient trials in adults providing
evidence of efficacy. Patients taking additional medication or not achieving
headache relief prior to 2 hours were censored at 2 hours.
There was a decreased incidence
of migraine-associated nausea, photophobia and phonophobia in VIOXX treated
patients compared to placebo. The estimated probability of taking other
medication for migraine over the 24 hours following initial dose of study
treatment is summarized in Figure 2.
Figure 2 : Estimated Probability of Patients Taking
Additional Medication for Migraines over the 24 Hours Following the Initial
Dose of Study Treatment
This Kaplan-Meier plot is based
on pooled data obtained in 2 placebo-controlled outpatient trials. Patients not
using additional medications were censored at 24 hours. The plot includes both
patients who had headache relief at 2 hours and those who had no response to
the initial dose. Additional medication was not allowed within 2 hours
postdose.
VIOXX was effective regardless
of presence of aura, gender, race, age, presence of menses or dysmenorrhea.
Similarly, the concomitant use of common migraine prophylactic drugs (e.g.,
beta-blockers, calcium channel blockers, tricyclic antidepressants) or oral
contraceptives did not affect efficacy. VIOXX was also effective whether or not
there was a history of prior response to NSAIDs. Special Studies
The following special studies
were conducted to evaluate the comparative safety of VIOXX.
VIOXX GI Clinical Outcomes
Research (VIGOR Study)
Study Design
The VIGOR study was designed to
evaluate the comparative GI safety of VIOXX 50 mg once daily (twice the highest
dose recommended for chronic use in OA and RA) versus naproxen 500 mg twice
daily (common therapeutic dose). The general safety and tolerability of VIOXX
50 mg once daily versus naproxen 500 mg twice daily was also studied. VIGOR was
a randomized, double-blind study (median duration of 9 months) in 8076 patients
with rheumatoid arthritis (RA) requiring chronic NSAID therapy (mean age 58
years). Patients were not permitted to use concomitant aspirin or other
antiplatelet drugs. Patients with a recent history of myocardial infarction or
stroke and patients deemed to require low-dose aspirin for cardiovascular
prophylaxis were to be excluded from the study. Fifty-six percent of patients
used concomitant oral corticosteroids. The GI safety endpoints (confirmed by a
blinded adjudication committee) included:
PUBs-symptomatic ulcers, upper
GI perforation, obstruction, major or minor upper GI bleeding.
Complicated PUBs (a subset of
PUBs)-upper GI perforation, obstruction or major upper GI bleeding.
Study Results
Gastrointestinal Safety in
VIGOR
The VIGOR study showed a
significant reduction in the risk of development of PUBs, including complicated
PUBs in patients taking VIOXX compared to naproxen (see Table 3).
Table 3 : VIGOR-Summary of Patients with
Gastrointestinal Safety Events1
COMPARISON TO
NAPROXEN
GI Safety Endpoints |
VIOXX 50 mq daily (N=4047)2 n3 (Cumulative Rate4) |
Naproxen 1000 mq daily (N=4029)2 n3 (Cumulative Rate4) |
Relative Risk of VIOXX compared to naproxen5 |
95% CI5 |
PUBs |
56 (1.80) |
121 (3.87) 7 |
0.46* |
(0.33, 0.64) |
Complicated PUBs |
16 (0.52) |
37 (1.22) |
0.43* |
(0.24, 0.78) |
1As confirmed by an independent committee
blinded to treatment,
2N=Patients randomized,
3n=Patients with events,
4Kaplan-Meier cumulative rate at end of study when at least 500
patients remained (approx. 10 ½ months),
5Based on Cox proportional hazard model
*p-value ≤ 0.005
for relative risk compared to naproxen |
The risk reduction for PUBs and
complicated PUBs for VIOXX compared to naproxen (approximately 50%) was
maintained in patients with or without the following risk factors for
developing a PUB (Kaplan-Meier cumulative rate of PUBs at approximately 10 ½
months, VIOXX versus naproxen, respectively): with a prior PUB (5.12, 11.47);
without a prior PUB (1.54, 3.27); age 65 or older (2.83, 6.49); or younger than
65 years of age (1.48, 3.01). A similar risk reduction for PUBs and complicated
PUBs (approximately 50%) was also maintained in patients with or without Helicobacter
pylori infection or concomitant corticosteroid use.
Other Safety Findings:
Cardiovascular Safety
The VIGOR study showed a higher
incidence of adjudicated serious cardiovascular thrombotic events in patients
treated with VIOXX 50 mg once daily as compared to patients treated with
naproxen 500 mg twice daily (see Table 4). This finding was largely due to a
difference in the incidence of myocardial infarction between the groups. (See
Table 5.) (see WARNINGS; Cardiovascular Thrombotic Events.) Adjudicated
serious cardiovascular events (confirmed by a blinded adjudication committee)
included: sudden death, myocardial infarction, unstable angina, ischemic
stroke, transient ischemic attack and peripheral venous and arterial thromboses.
Table 4 : VIGOR-Summary of Patients with Serious
Cardiovascular Thrombotic Adverse Events1 Over Time COMPARISON TO
NAPROXEN
Treatment Group |
Patients Randomized |
|
4 Months2 |
8 Months3 |
10 % months4 |
VIOXX 50 mg |
4047 |
Total number of events |
17 |
29 |
45 |
Cumulative Rate† |
0.46% |
0.82% |
1.81%* |
Naproxen 1000 mg |
4029 |
Total number of events |
9 |
15 |
19 |
Cumulative Rate† |
0.23% |
0.43% |
0.60% |
1Confirmed by blinded adjudication committee,
2Number of patients remaining after 4 months were 3405 and 3395 for
VIOXX and naproxen respectively,
3Number of patients remaining after 8 months were 2806 and 2798 for
VIOXX and naproxen respectively,
4Number of patients remaining were 531 and 514 for VIOXX and
naproxen respectively.
†Kaplan-Meier cumulative rate.
* p-value < 0.002 for the overall relative risk compared to naproxen by Cox
proportional hazard model |
Table 5 : VIGOR- Serious Cardiovascular Thrombotic
Adverse Events 1
|
VIOXX 50 mg
N2=4047 n3 |
Naproxen 1000 mg
N2=4029 n3 |
Any CV thrombotic event |
45 * |
19 |
Cardiac events |
28** |
10 |
Fatal MI/Sudden death |
5 |
4 |
Non-fatal MI |
18** |
4 |
Unstable angina |
5 |
2 |
Cerebrovascular |
11 |
8 |
Ischemic stroke |
9 |
8 |
TIA |
2 |
0 |
Peripheral |
6 |
1 |
1Confirmed by blinded adjudication committee,
2N=Patients randomized,
3n=Patients with events
* p-value < 0.002 and ** p-value ≤ 0.006 for relative risk compared to
naproxen by Cox proportional hazard model |
For cardiovascular data from 2
long-term placebo-controlled studies, see WARNINGS, Cardiovascular
Thrombotic Events.
Upper Endoscopy in Patients
with Osteoarthritis and Rheumatoid Arthritis
The VIGOR study described above
compared clinically relevant outcomes. Several studies summarized below have
utilized scheduled endoscopic evaluations to assess the occurrence of
asymptomatic ulcers in individual patients taking VIOXX or a comparative agent.
The results of outcomes studies, such as VIGOR, are more clinically relevant
than the results of endoscopy studies (see Clinical Studies, Special
Studies, VIGOR).
Two identical (U.S. and
Multinational) endoscopy studies in a total of 1516 patients were conducted to
compare the percentage of patients who developed endoscopically detectable
gastroduodenal ulcers with VIOXX 25 mg daily or 50 mg daily, ibuprofen 2400 mg
daily, or placebo. Entry criteria for these studies permitted enrollment of
patients with active Helicobacter pylori infection, baseline gastroduodenal
erosions, prior history of an upper gastrointestinal perforation, ulcer, or
bleed (PUB), and/or age ≥ 65 years.
However, patients receiving aspirin (including
low-dose aspirin for cardiovascular prophylaxis) were not enrolled in these
studies. Patients who were 50 years of age and older with osteoarthritis and
who had no ulcers at baseline were evaluated by endoscopy after weeks 6, 12,
and 24 of treatment. The placebo-treatment group was discontinued at week 16 by
design.
Treatment with VIOXX 25 mg
daily or 50 mg daily was associated with a significantly lower percentage of
patients with endoscopic gastroduodenal ulcers than treatment with ibuprofen
2400 mg daily. See Figures 3 and 4 for the results of these studies.
Figure 3 : COMPARISON TO
IBUPROFEN
Life-Table Cumulative Incidence Rate of Gastroduodenal Ulcers ≥ 3 mm**
(Intention-to-Treat)
† p < 0.001 versus ibuprofen
2400 mg
** Results of analyses using a ≥ 5mm
gastroduodenal ulcer endpoint were consistent.
*** The primary endpoint was the cumulative incidence of gastroduodenal ulcer
at 12 weeks.
Figure 4 : COMPARISON TO
IBUPROFEN Â
Life-Table Cumulative Incidence Rate of Gastroduodenal Ulcers
≥ 3 mm** (Intention-to-Treat)
† p < 0.001 versus ibuprofen
2400 mg
** Results of analyses using a ≥ 5mm gastroduodenal ulcer
endpoint were consistent.
*** The primary endpoint was the cumulative incidence
of gastroduodenal ulcer at 12 weeks.
In a similarly designed 12-week
endoscopy study in RA patients treated with VIOXX 50 mg once daily (twice the
highest dose recommended for chronic use in OA and RA) or naproxen 1000 mg
daily (common therapeutic dose), treatment with VIOXX was associated with a
significantly lower percentage of patients with endoscopic gastroduodenal
ulcers than treatment with naproxen.
A similarly designed 12-week
endoscopy study was conducted in OA patients treated with low-dose enteric
coated aspirin 81 mg daily, low-dose enteric coated aspirin 81 mg plus VIOXX 25
mg daily, ibuprofen 2400 mg daily, or placebo. There was no difference in the
cumulative incidence of endoscopic gastroduodenal ulcers in patients taking
low-dose aspirin plus VIOXX 25 mg as compared to those taking ibuprofen 2400 mg
daily alone. Patients taking low-dose aspirin plus ibuprofen were not studied. (see
PRECAUTIONS: DRUG INTERACTIONS,)
Serious clinically significant
upper GI bleeding has been observed in patients receiving VIOXX in controlled
trials, albeit infrequently (see WARNINGS; Gastrointestinal Bleeding,
Ulceration, and Perforation).
Assessment of Fecal Occult
Blood Loss in Healthy Subjects
Occult fecal blood loss
associated with VIOXX 25 mg daily, VIOXX 50 mg daily, ibuprofen 2400 mg per
day, and placebo was evaluated in a study utilizing 51Cr-tagged red blood cells
in 67 healthy males. After 4 weeks of treatment with VIOXX 25 mg daily or VIOXX
50 mg daily, the increase in the amount of fecal blood loss was not
statistically significant compared with placebo-treated subjects. In contrast,
ibuprofen 2400 mg per day produced a statistically significant increase in
fecal blood loss as compared with placebo-treated subjects and VIOXX-treated
subjects. The clinical relevance of this finding is unknown.
Platelets
Multiple doses of VIOXX 12.5,
25, and up to 375 mg administered daily up to 12 days had no effect on bleeding
time relative to placebo. There was no inhibition of ex vivo arachidonic acid-
or collagen-induced platelet aggregation with 12.5, 25, and 50 mg of VIOXX.
Because of its lack of
platelet effects, VIOXX is not a substitute for aspirin for cardiovascular
prophylaxis. (see WARNINGS; Cardiovascular Thrombotic Events).
Pediatric Patients
Pauciarticular and
Polyarticular Course Juvenile Rheumatoid Arthritis (JRA)
In a 12-week, double-blind
active-controlled, non-inferiority study, 310 patients, 2 years to 17 years of
age with pauciarticular or polyarticular course JRA, received the following
treatments: lower-dose VIOXX 0.3 mg/kg (to a maximum of 12.5 mg) once daily in
patients ≥ 2 years to ≤ 11 years
of age or VIOXX 12.5 mg once daily in patients
≥ 12 years to ≤ 17 years of age;
higher-dose VIOXX 0.6 mg/kg (to a maximum of 25 mg) once daily in patients
≥ 2 years to ≤ 11 years of age or VIOXX 25 mg once daily in patients ≥
12 years to ≤ 17 years of age; NSAID comparator targeted to an effective
dose in patients ≥ 2 years to ≤ 17 years of age. The response
rates were based upon the JRA Definition of Improvement ≥ 30% (JRA DOI
30) criterion, which is a composite of clinical,
laboratory, and functional measures of JRA. The JRA DOI 30 response rates were
55% in both the VIOXX 0.6 mg/kg (to a maximum of 25 mg) and NSAID comparator
treatment groups achieving the non-inferiority criterion. A single
non-inferiority trial is not sufficient to support a conclusion of equivalence.
In a 52-week open-label
extension to the 12-week study, 160 patients received VIOXX 0.6 mg/kg to a
maximum of 25 mg once daily (patients ≥
2 years to ≤ 11 years of age) or 25 mg once daily (patients ≥ 12
years to ≤ 17 years of age) and 67 patients ≥ 2 years to ≤
17 years of age received NSAID comparator targeted to an effective dose. There
were no unexpected safety findings.