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NSAIDs, Coxibs, and Cardio-Renal Physiology
A Mechanism-Based Evaluation
COX-2 Hypothesis and GI Outcome Studies With Coxibs
Phospholipase A2
Membrane-bound phospholipids
Arachidonic acid
OO22
PGG2
PGH2
PGF2PGE2PGD2 PGI2 TxA2
COX-1
COX-2
COX = cyclooxygenase; coxibs = COX-2 inhibitors; PG = prostaglandin; TxA2 = thromboxane A2;
NSAID = nonsteroidal anti-inflammatory drug; ASA = aspirin.
NSAIDs, ASA
Coxibs
Tissue-specific isomerases
Prostaglandin and Thromboxane Biosynthesis
The COX-2 Hypothesis
PGsPGs
COX-1constitutive
COX-2inducible
Inflammation Fever Pain Headache
Carcinogenesis
GI cytoprotection Platelet aggregation Renal function
(blood flow)
Arachidonic acid
Caveats to COX-2 Hypothesis Constitutive COX-2 expression in kidney and brain Co-expression of COX-1 and COX-2 at sites of
inflammation Hemodynamic induction of COX-2
Testing the COX-2 Hypothesis At therapeutic plasma concentrations,
coxibs should
– Have no effect on COX-1 activity
– Spare the GI tract
In clinical studies of equally efficacious doses, coxibs should exhibit fewer GI adverse effects than NSAIDs
NSAIDs: COX-2 vs COX-1 Selectivity
FitzGerald and Patrono. N Engl J Med. 2001;345:433.
COX-1 IC50 (µM)
CO
X-2
IC50
(µ
M)
100.00
0.10
0.010.01 0.10 1.00 10.00 100.00
10.00
1.00
6-MNA
Acetaminophen
Rofecoxib
Nimesulide
Celecoxib
Meloxicam
Naproxen
Indomethacin
Diclofenac
Ibuprofen
6-MNA = 6-methoxy-2-naphthylacetic acid; IC50 = drug concentration at which the enzymatic activity is inhibited by 50%.
RofecoxibCelecoxib
Metabolism
Median Tmax = 2–3 hours
T1/2 = 17 hours
Steady state reached: 4 days
Tmax = 2.8 hours
T1/2 = 11.2 hours
Steady state reached: 5 days
KineticsAccumulation
Absorption time
In liver via P450 2C9
Linear No
60% in liver via cytosolic reductase40% in liver via P450 3A4
Nonlinear, saturable
Yes; accumulation factor: 1.67
Sulfonamide Sulfone
F
Vioxx® package insert, Merck & Co, Inc.; Celebrex® package insert, G.D. Searle & Co.
Oral bioavailability 22%–40% 92%–93%
Coxibs: Pharmacologic CharacteristicsO
O
NH2
CF3
N
S
N
CH3
F
OO
O
H3CS
O
Laine et al. Gastroenterology. 1999;117:776.
Patients: N=742, osteoarthritis
Cu
mu
lati
ve i
nci
den
ce o
f g
astr
od
uo
den
al u
lcer
s* (
%)
* ≥3 mm.† P<0.001 vs ibuprofen.
At doses 2- to 4-fold higher than the doses required to relieve symptoms of OA, rofecoxib caused significantly fewer gastroduodenal ulcers than ibuprofen
Upper GI Effect of Rofecoxib: Endoscopic Study
Placebo(n=158)
Ibuprofen 2400 mg(n=167)
Rofecoxib 25 mg(n=186)
Rofecoxib 50 mg(n=178)
Time of treatmentWeek 12 Week 24
0
10
20
30
40
50
†
†
Simon et al. JAMA. 1999;282:1921.
Patients: N=1149, rheumatoid arthritis
0
5
10
15
20
25
30
Placebo (n=99)
Celecoxib 200 mg(n=148)
Celecoxib400 mg(n=145)
Celecoxib800 mg(n=130)
Naproxen1000 mg(n=137)
P<0.001 vs other groups
Gas
tro
du
od
enal
ulc
er
inci
den
ce*
ove
r 12
-wee
ktr
eatm
ent
per
iod
(%
)
Celecoxib produced significantly fewer visualized gastroduodenal ulcers than naproxen
Upper GI Effect of Celecoxib: Endoscopic Study
CLASS† (N=7982)VIGOR* (N=8076)
Bombardier et al. N Engl J Med. 2000;343:1520; Silverstein et al. JAMA. 2000;284:1247; FDA Advisory Committee Meeting, 2001, Gaithersburg, Md; FDA Arthritis Advisory Committee, 2001, Gaithersburg, Md.
Celecoxib 400 mg bid(2x max chronic dose)
Rofecoxib 50 mg qd(2x max chronic dose)
Drug
Yes (21%)NoASA (≤325 mg/d)
Ibuprofen 800 mg tidDiclofenac 75 mg bid
Naproxen 500 mg bidComparator
OA (72%), RA (28%)RAPatients
Duration Median 9 months Median 9 months
Symptomatic + complicated ulcersComplicated upper GI events2° end point
Complicated ulcersClinical upper GI events1° end point
* Vioxx Gastrointestinal Outcomes Research. † Celecoxib Long-Term Arthritis Safety Study.
GI Outcomes With Coxibs: Study Designs
Bombardier et al. N Engl J Med. 2000;343:1520; FDA Advisory Committee Meeting, 2001. Gaithersburg, Md.
1° End Point—Clinical UGI Event
Cu
mu
lati
ve in
cid
ence
(%
)
2° End Point—Complicated UGI Event
Cu
mu
lati
ve in
cid
ence
(%
)Months of follow-up
0
Rofecoxib
Naproxen
0.0
1.0
2.0
3.0
4.0
5.0
2 4 6 8 10 12
(RR=0.46; P<0.001)Rofecoxib
Naproxen
0
0.5
1.0
1.5
0 2 4 6 8 10 12
Months of follow-up
(RR=0.43; P=0.005)
GI Outcomes of VIGOR Study
2° End Point—Symptomatic Ulcers/Ulcer Complications
1° End Point—Ulcer Complications
Silverstein et al. JAMA. 2000;284:1247; FDA Arthritis Advisory Committee, 2001. Gaithersburg, Md.
4
3
2
1
0
0 100 200 300 380Days
Celecoxib 400 mg bidDiclofenac 75 mg bidIbuprofen 800 mg tid
0 3202001000
1
Days
2
% o
f p
atie
nts
GI Outcomes of CLASS
% o
f p
atie
nts
VIGOR– Compared with naproxen, rofecoxib significantly decreases the risk of
Clinical upper GI events
Complicated events
All GI bleeding
– Rofecoxib has similar efficacy to naproxen against RA CLASS
– No significant differences between celecoxib and nonspecific NSAID comparators for primary end point of complicated ulcers
– Celecoxib is associated with a lower rate of symptomatic and complicated ulcers compared with ibuprofen alone
Bombardier et al. N Engl J Med. 2000;343:1520; Silverstein et al. JAMA. 2000;284:1247;
FDA Arthritis Advisory Committee, 2001. Gaithersburg, Md.
GI Outcome Studies With Coxibs: Summary
NSAIDs and Coxibs: Renal Physiology
Arachidonic Acid
PGI2PGE2
Decreases Na+ reabsorption
Brater. Am J Med. 1999;107:65S.
Stimulates renin release secretion of aldosterone
K+ secretionVasodilation
- GFR- Renal blood flow
COX-1, COX-2
GFR = glomerular filtration rate.
Role of Prostaglandins in the Kidney
Constitutive Expression of COX-1 and COX-2 in the Kidney
Nantel et al. Nantel et al. FEBS LettersFEBS Letters. 1999;457:475; Schnermann et al. . 1999;457:475; Schnermann et al. J Clin InvestJ Clin Invest. 1999;104:1007.. 1999;104:1007.
Renin-secretingRenin-secretinggranular cellsgranular cells
Loop of HenleLoop of Henle
Efferent arteriole: COX-1, COX-2Efferent arteriole: COX-1, COX-2
Macula densa: Macula densa: COX-2COX-2
Distal tubuleDistal tubule
Afferent arteriole: Afferent arteriole: COX-1, COX-2COX-1, COX-2
ThickThickascendingascending
limb:limb:COX-2COX-2
Proximal Proximal convoluted tubuleconvoluted tubule
Glomerulus: Glomerulus: COX-1, COX-2COX-1, COX-2
Podocytes: COX-2Podocytes: COX-2
Harris and Breyer. Am J Physiol Renal Physiol. 2001;281:F1; Whelton. Am J Med. 2001;110(suppl 3A):33S.
Intrarenal Functional Roles of COX-2 and COX-1
COX-2 expression can be up-regulated– In the renal cortex by volume restriction – In the renal medulla by volume expansion – In high renin states (such as salt-restriction,
ACE inhibition, and renovascular hypertension) COX-2—dominant contributor to Na+, Cl–, and water
homeostasis under physiologic conditions COX-1—important role in hemodynamic regulation
under physiologic conditions
Potential Effects of NSAIDs on Renal Physiology
Brater. Am J Med. 1999;107:65S.
CHF = congestive heart failure.
PGI2
Hyperkalemia Acute renal failure
PGE2
Sodium retention• Peripheral edema• Blood pressure• Weight• CHF (rarely)
Arachidonic acid
COX-1
COX-2
NSAIDs
Ioh
exo
l cle
aran
ce*
(mL
/min
/1.7
3 m
2 )
P<0.05 vs rofecoxib
P<0.05 vs celecoxib
Celecoxib200 mg
bid
Naproxen500 mg
bid
Celecoxib400 mg
bid
Naproxen500 mg
bid
-8-8
-6-6
-4-4
-2-2
00
22
44Placebo Rofecoxib
50 mg qdIndomethacin
50 mg qd
-8-8
-6-6
-4-4
-2-2
00
22
44
Catella-Lawson et al. J Pharmacol Exp Ther. 1999;289:735; Whelton et al. Arch Intern Med. 2000;160:1465.
* Mean ± (SE) change from baseline GFR.
COX-1–Dependent Regulation of GFR in Healthy Elderly on a Sodium-Replete Diet
* P<0.05 vs placebo.† P=0.086 vs placebo.
% R
edu
ctio
n in
io
thal
amat
e cl
eara
nce
Swan et al. Ann Intern Med. 2000;133:1.
0.00
0.05
0.15
0.10
0.20
0.25
Placebo(n=15)
Rofecoxib12.5 mg qd
(n=15)
Rofecoxib25 mg qd
(n=15)
Indomethacin50 mg tid
(n=15)
* *†
COX-2–Dependent Regulation of GFR in Healthy Elderly
on a Sodium-Depleted Diet
* Investigator-reported.
1. Summary basis for approval, FDA. 2. FDA Advisory Committee Meeting, 2001.
% o
f p
atie
nts
3.8 3.4
Ibuprofen2400 mg
n=847
Diclofenac150 mgn=498
3.6 3.8
Rofecoxib25 mgn=1614
Rofecoxib12.5 mgn=1215
Phase II/III OA studies1 VIGOR study2
Rofecoxib50 mgn=4047
Naproxen1000 mgn=4029
5.4
3.6
Dose-Dependent Incidence of Lower-Extremity Edema*: Rofecoxib Trials
0.0
2.0
4.0
6.0
8.0
10.0
* Peripheral edema includes both upper- and lower-extremity edema (investigator-reported). † P<0.05 vs celecoxib; ‡ Naproxen, diclofenac.
1. Summary basis for approval, FDA. 2. FDA Arthritis Advisory Committee Meeting, 1-year data, 2001.
Dose-Dependent Incidence of Peripheral Edema*: Celecoxib Trials
1.93.0
2.4
3.7 3.5
5.2
2.0
4.0
6.0
8.0
10.0
% o
f p
atie
nts
Celecoxib
400 mgn=1208
NSAID Comparator‡
n=1388
Ibuprofen 2400 mgn=1985
Diclofenac 150 mgn=1996
Celecoxib 200 mgn=1764
Phase II/III OA studies1 CLASS2
Celecoxib
800 mgn=3987
†
0.0
1. Summary basis for approval, FDA. 2. FDA Advisory Committee Meeting, 2001.
* Investigator-reported adverse experiences.
Hypertension* Reports: Rofecoxib
VIGOR study2
2.8
4.0
% o
f p
atie
nts
Rofecoxib25 mgn=1614
Rofecoxib12.5 mgn=1215
Phase II/III OA studies1
Rofecoxib 50 mg n=4047
Naproxen 1000 mg n=4029
9.7
5.5
2.9
1.6
Ibuprofen2400 mg
n=847
Diclofenac150 mgn=498
2.0
4.0
6.0
8.0
10.0
0.0
0.71.20.9
2.0 2.0
3.1
% o
f p
atie
nts
Celecoxib 400 mgn=1208
NSAID Comparator†
n=1388
Ibuprofen 2400 mgn=1985
Diclofenac 150 mgn=1996
Celecoxib 200 mgn=1764
Phase II/III OA studies1 CLASS2
Celecoxib 800 mgn=3987
1. Summary basis for approval, FDA.2. FDA Arthritis Advisory Committee Meeting, 2001.
* Investigator-reported.† Naproxen, diclofenac.
Hypertension* Reports: Celecoxib
0.0
1.0
2.0
3.0
4.0
-2
-1
0
1
2
3
4
5
Schwartz et al. EULAR, 2001. Abstract SAT0055.
Effect of Naproxen and Coxibs onBlood Pressure in the Elderly
Placebo (n=16)Naproxen 500 mg bid (n=17)
Celecoxib 200 mg bid (n=17)Rofecoxib 25 mg qd (n=17)
Systolic BP Diastolic BP
Changes in BP on Day 14 of Treatment
LS
mea
n c
han
ge
fro
m b
asel
ine
± S
E
-3
6
7
Renal Effects of Coxibs and NSAIDs: Summary
So far, the renal adverse event profile of coxibs resembles that of nonspecific NSAIDs
Limited information is available regarding the contribution of COX isoforms to function under conditions of renal stress and insufficiency
Clinically significant decline in renal function with coxibs is rare; however, few studies in susceptible populations have analyzed it
Comparative studies of coxibs and nonspecific NSAIDs in hypertension and edema, which adjust for pharmacologic differences, are required
NSAIDs and Coxibs: Cardiovascular Biology
Effects of NSAIDs on Platelets and Endothelium
McAdam et al. Proc Natl Acad Sci USA. 1999;96:272.
Thromboxane (TxA2)
Vasoconstrictor Promotes platelet aggregation
Platelet
Hemostasis Thrombosis
COX-1
VasodilatorInhibitor of platelet aggregation
Endothelial cell
Prostacyclin (PGI2)
COX-1
COX-2
Nonspecific NSAIDs/ASA
Coxibs
Comparative Inhibitory Activity of NSAIDs on Platelet Aggregation
McAdam et al. Proc Natl Acad Sci USA. 1999;96:272.
*20 M arachidonate used as agonist.
Inh
ibit
ion
of
pla
tele
t ag
gre
gat
ion
*(%
ch
ang
e fr
om
bas
elin
e)
0
100
Placebo
20
IbuprofenCelecoxib (mg)
100 400 800
40
60
80
10
30
50
70
90
P<0.01 vs placebo
Event CategoryRofecoxib(n=4047)
Naproxen(n=4029)
Relative Risk(95% CI)
Cardiac 28 (1.0) 10 (0.4)
Cerebrovascular* 11 (0.4) 8 (0.3)
Peripheral vascular 6 (0.2) 1 (0.0 4)
Confirmed CV 45 (1.7) 19 (0.7)
Patients With Events (Rates per 100 Patient-Years)
0.36
0.73
0.17
0.420 1 2
Patients: RA Aspirin treatment: not allowed
* Not including hemorrhagic stroke.
FDA Advisory Committee Meeting, 2001.
CV Adverse Events: VIGOR
CV Adverse Events: CLASS
% of Patients With Events
Celecoxib Diclofenac Ibuprofen
Event (n=3988) (n=1996) (n=1985)
MI 20 (0.5) 6 (0.3) 10 (0.5)
Angina24 (0.6) 10 (0.5) 12 (0.6)
Unstable angina 12 (0.3) 4 (0.2) 2 (0.1)
Any event 100 (2.5) 42 (2.1) 44 (2.2)
Withdrawals 32 (0.8) 14 (0.7) 16 (0.8)
Patients: 72% with OA and 28% with RA Aspirin treatment: 21% of patients
FDA Arthritis Advisory Committee Meeting, 2001.
FitzGerald and Patrono. N Engl J Med. 2001;345:433.
CV Biology and COX-2 Inhibition: Hypotheses Generated by VIGOR Results
Play of chance?
Thrombogenic risk with coxibs?
Is naproxen cardioprotective?
FitzGerald and Patrono. N Engl J Med. 2001;345:433.
CV Biology and COX-2 Inhibition: Hypotheses Generated by VIGOR Results
(cont’d)
Play of chance?
– Small number of events (<70, 1.7%)
CV Biology and COX-2 Inhibition: Hypotheses Generated by VIGOR Results
(cont’d)
Thrombogenic risk with coxibs?– Coxibs inhibit PGI2, an antithrombotic agent
– Thromboxane formation is unopposed by concomitant generation of PGI2
– In mice, deletion of the PGI2 receptor increases the response to thrombogenic stimuli
– Patients with RA have an increased risk of thrombosis
Effect of Celecoxib and Rofecoxib on Prostacyclin Biosynthesis
* PGI-M = 2,3-dinor-6-keto-PGF1; † P<0.01 vs placebo; ‡ P<0.05 vs placebo.
0
40
80
120
160
200
Placebo(n=7)
Celecoxib 400 mg(n=7)
Ibuprofen 800 mg(n=7)
Mea
n u
rin
ary
PG
I-M
* ±
SE
(p
g/m
g c
reat
inin
e)
†
‡
Placebo(n=12)
Rofecoxib50 mg qd
(n=12)
Indomethacin50 mg tid
(n=10)
†
†
0
40
80
120
160
200
McAdam et al. Proc Natl Acad Sci USA. 1999;96:272; Catella-Lawson et al. J Pharmacol Exp Ther. 1999;289:735.
Celecoxib 800 mg(n=7)
†
1 Myllykangas-Luosujarvi et al. Semin Arthritis Rheum. 1995;25:193.2 Wolfe and Straus. Arthritis Rheum. 2000;43(9 suppl):S133.Doggen et al. J Intern Med. 2000;248:406; Devlin et al. J Rheumatol. 1997;24:9.
CV Morbidity and Mortality in RA Increasing evidence suggests a role of inflammation in coronary
events Most studies have shown that patients with RA have increased CV
mortality relative to patients of the same age and sex without RA1
– Standardized mortality ratios: 1.1:2.5
One recent study2 has shown increased CV risk (OR=2.0) in RA patients relative to OA patients, adjusting for age, gender, and other covariates
Patients with RA have increased plasma levels of C-reactive protein, which correlate with an increased CV risk
MI and CV Death
RA vs OA
Men*
Women*
Overall†
1.26 (1.14, 1.40)
1.37 (1.26, 1.49)
1.32 (1.24, 1.41)
RA vs No Arthritis
Men*
Women*
Overall†
1.43 (1.29, 1.58)
1.63 (1.50, 1.76)
1.55 (1.46, 1.65)
* Adjusted for age. † Adjusted for age and gender.
1.40 (1.22, 1.61) 1.49 (1.36, 1.69) 1.41 (1.24, 1.61)
1.40 (1.22, 1.60)1.49 (1.36, 1.63)1.45 (1.35, 1.57)
MI CV Death
Adjusted Rate Ratios (95% CI)
Watson and Rhodes. EULAR, 2001. Abstract OP0109.
CV Biology and COX-2 Inhibition: Hypotheses Generated by VIGOR Results (cont’d)
Is naproxen cardioprotective?
– Naproxen has a potent antiplatelet effect with an extended half-life
– No prospective evaluation of naproxen on CV outcome
Inhibition From Baseline During Dosing Interval
0 2 4 8
Hours after dose
Me
an
% in
hib
itio
n
SE Naproxen
500 mg bid
Placebo
Ibuprofen800 mg tid
100
80
60
40
20
0
-20
FDA Advisory Committee Meeting, 2001.
Effect of NSAIDs on Platelet Aggregation
Bombardier et al. N Engl J Med. 2000;343:1520.
CVA = cerebrovascular accident; TIA = transient ischemic attack; CABG = coronary artery bypass surgery;PTCA = percutaneous transluminal coronary angioplasty.
Importance of Antiplatelet Therapy in Patients With CV Risk: VIGOR
4% of enrolled patients met established criteria for secondary CV prophylaxis (prior MI, CVA, TIA, angina, CABG, PTCA)
– 47% of Mls occurred in this group
No correlation between hypertension and MIs; 1 patient had both hypertension and an MI
Baigent et al. BMJ. 1998;316:1337; Antiplatelet Trialists’ Collaboration. BMJ. 1994;308:81; Physicians’ Health Study Research Group. N Engl J Med. 1989;321:129; Patrono et al. Chest. 2001;119:39S.
Cardioprotective Properties of Aspirin
ASA is clearly indicated after heart attack and stroke– Acute MI (ISIS-2)
23% mortality 49% reinfarction
– Secondary prevention (APTC) 25% in nonfatal MI/stroke/vascular death
Evidence unclear in primary prevention
Rofecoxib50 mg qd (n=4047)
Naproxen500 mg bid
(n=4029)
VIGOR Study1
0.2
0.4
0.6
0.8
1.0
Ra
tes
pe
r 10
0 p
ati
ent-
ye
ars
Celecoxib400 mg bid
(n=3995)
Diclofenac75 mg tid(n=1999)
Ibuprofen800 mg bid
(n=1998)
CLASS Study2
0.2
0.4
0.6
0.8
1.0
1. FDA Advisory Committee Meeting, 2001. 2. FDA Arthritis Advisory Committee Meeting, 2001.
Incidence of MI in Rofecoxib and Celecoxib GI Outcome Studies
0.0 0.0
Nonspecific NSAIDs and Coxibs: CV Biology—Summary
The rate of CV events diverges between the 2 treatment groups in VIGOR; this may result from chance
Two mechanistic hypotheses may explain the distribution of CV events among the treatment groups; they are not mutually exclusive– Suppression of PGI2 (no ASA, RA population)
– Naproxen may have a cardioprotective effect There is no evidence that coxibs alone increase CV risk Patients at high risk for CV events should receive therapy
providing cardioprotection– Controlled clinical trials needed to examine whether patients receiving coxibs
+ ASA will experience fewer GI AEs compared with those receiving NSAIDs ± ASA
Summary
Rofecoxib, compared with naproxen at equally efficacious doses, significantly decreases the risk of upper GI events
Based on available evidence, the renal adverse event profile of coxibs resembles that of NSAIDs, to date
Distribution of CV events in VIGOR may be explained by chance; 2 possible mechanistic hypotheses proposed
Risk of CV and renal adverse events needs to be evaluated in patients prior to initiation of coxib therapy
N Eng J Med 345:1809, 2001