CLINICAL PHARMACOLOGY
Pharmacodynamics
CLINORIL (sulindac) is a non-steroidal anti-inflammatory drug (NSAID) that exhibits anti-inflammatory,
analgesic and antipyretic activities in animal models. The mechanism of action,
like that of other NSAIDs, is not completely understood but may be related to prostaglandin synthetase inhibition.
Pharmacokinetics
Absorption
The extent of sulindac absorption from CLINORIL Tablets is similar as compared
to sulindac solution.
There is no information regarding food effect on sulindac absorption. Antacids
containing magnesium hydroxide 200 mg and aluminum hydroxide 225 mg per 5 mL
have been shown not to significantly decrease the extent of sulindac absorption.
TABLE 1
PHARMACOKINETIC PARAMETERS |
NORMAL |
ELDERLY |
Tmax |
Age 19-41 (n=24) |
Age 65-87 (n=12) 400 mg qd |
(200 mg tablet) |
2.54 ± 1.52 S |
3.38 ± 2.30 S |
5.75 ± 2.81 SF |
4.88 ± 2.57 SP |
6.83 ± 4.19 SP |
4.96 ± 2.36 SF |
|
(150 mg tablet) |
|
3.90 ± 2.30 S |
|
5.85 ±4.49 SP |
|
6.15 ± 3.07 SF |
|
Renal Clearance |
200 mg tablet) |
|
68.12 ± 27.56 mL/min S |
|
36.58 ± 12.61 mL/min SP |
|
150 mg tablet) |
|
74.39 ± 34.15 mL/min S |
|
41.75 ± 13.72 mL/min SP |
|
Mean effective Half life(h) |
7.8 S |
|
16.4 SF |
|
S = Sulindac |
|
SF = Sulindac Sulfide |
|
SP = Sulindac Sulfone |
|
Distribution
Sulindac, and its sulfone and sulfide metabolites, are 93.1, 95.4, and 97.9%
bound to plasma proteins, predominantly to albumin. Plasma protein binding measured
over a concentration range (0.5-2.0 μg/mL) was constant. Following an oral,
radiolabeled dose of sulindac in rats, concentrations of radiolabel in red blood
cells were about 10% of those in plasma. Sulindac penetrates the blood-brain
and placental barriers. Concentrations in brain did not exceed 4% of those in
plasma. Plasma concentrations in the placenta and in the fetus were less than
25% and 5% respectively, of systemic plasma concentrations. Sulindac is excreted
in rat milk; concentrations in milk were 10 to 20% of those levels in plasma.
It is not known if sulindac is excreted in human milk.
Metabolism
Sulindac undergoes two major biotransformations of its sulfoxide moiety: oxidation
to the inactive sulfone and reduction to the pharmacologically active sulfide.
The latter is readily reversible in animals and in man. These metabolites are
present as unchanged compounds in plasma and principally as glucuronide conjugates
in human urine and bile. A dihydroxydihydro analog has also been identified
as a minor metabolite in human urine.
With the twice-a-day dosage regimen, plasma concentrations of sulindac and
its two metabolites accumulate: mean concentration over a dosage interval at
steady state relative to the first dose averages 1.5 and 2.5 times higher, respectively,
for sulindac and its active sulfide metabolite.
Sulindac and its sulfone metabolite undergo extensive enterohepatic circulation
relative to the sulfide metabolite in animals. Studies in man have also demonstrated
that recirculation of the parent drug sulindac and its sulfone metabolite is
more extensive than that of the active sulfide metabolite. The active sulfide
metabolite accounts for less than six percent of the total intestinal exposure
to sulindac and its metabolites.
Biochemical as well as pharmacological evidence indicates that the activity
of sulindac resides in its sulfide metabolite. An in-vitro assay for inhibition
of cyclooxygenase activity exhibited an EC50 of 0.02 μM for sulindac sulfide.
In-vivo models of inflammation indicate that activity is more highly correlated
with concentrations of the metabolite than with parent drug concentrations.
Elimination
Approximately 50% of the administered dose of sulindac is excreted in the urine
with the conjugated sulfone metabolite accounting for the major portion. Less
than 1% of the administered dose of sulindac appears in the urine as the sulfide
metabolite. Approximately 25% is found in the feces, primarily as the sulfone
and sulfide metabolites.
The mean effective half-life (T½) is 7.8 and 16.4 hours, respectively,
for sulindac and its active sulfide metabolite.
Because CLINORIL (sulindac) is excreted in the urine primarily as biologically inactive
forms, it may possibly affect renal function to a lesser extent than other non-steroidal
anti-inflammatory drugs; however, renal adverse experiences have been reported
with CLINORIL (see ADVERSE REACTIONS).
In a study of patients with chronic glomerular disease treated with therapeutic
doses of CLINORIL (sulindac) , no effect was demonstrated on renal blood flow, glomerular
filtration rate, or urinary excretion of prostaglandin E2 and the primary metabolite
of prostacyclin, 6-keto-PGF1α. However, in other studies in healthy volunteers
and patients with liver disease, CLINORIL (sulindac) was found to blunt the renal responses
to intravenous furosemide, i.e., the diuresis, natriuresis, increments in plasma
renin activity and urinary excretion of prostaglandins. These observations may
represent a differentiation of the effects of CLINORIL (sulindac) on renal functions based
on differences in pathogenesis of the renal prostaglandin dependence associated
with differing dose-response relationships of different NSAIDs to the various
renal functions influenced by prostaglandins (see PRECAUTIONS).
In healthy men, the average fecal blood loss, measured over a two-week period
during administration of 400 mg per day of CLINORIL (sulindac) , was similar to that for placebo, and was statistically significantly less than that resulting from 4800
mg per day of aspirin.
Special Populations
Pediatric
The pharmacokinetics of sulindac have not been investigated in pediatric patients.
Race
Pharmacokinetic differences due to race have not been identified.
Hepatic Insufficiency
Patients with acute and chronic hepatic disease may require reduced doses of
CLINORIL (sulindac) compared to patients with normal hepatic function since hepatic metabolism
is an important elimination pathway.
Following a single dose, plasma concentrations of the active sulfide metabolite
have been reported to be higher in patients with alcoholic liver disease compared
to healthy normal subjects.
Renal Insufficiency
Sulindac pharmacokinetics have been investigated in patients with renal insufficiency.
The disposition of sulindac was studied in end-stage renal disease patients
requiring hemodialysis. Plasma concentrations of sulindac and its sulfone metabolite
were comparable to those of normal healthy volunteers whereas concentrations
of the active sulfide metabolite were significantly reduced. Plasma protein
binding was reduced and the AUC of the unbound sulfide metabolite was about
half that in healthy subjects.
Sulindac and its metabolites are not significantly removed from the blood in
patients undergoing hemodialysis.
Since CLINORIL (sulindac) is eliminated primarily by the kidneys, patients with significantly
impaired renal function should be closely monitored.
A lower daily dosage should be anticipated to avoid excessive drug accumulation.
In controlled clinical studies CLINORIL (sulindac) was evaluated in the following five
conditions:
Osteoarthritis
In patients with osteoarthritis of the hip and knee, the anti-inflammatory
and analgesic activity of CLINORIL (sulindac) was demonstrated by clinical measurements
that included: assessments by both patient and investigator of overall response;
decrease in disease activity as assessed by both patient and investigator; improvement
in ARA Functional Class; relief of night pain; improvement in overall evaluation
of pain, including pain on weight bearing and pain on active and passive motion;
improvement in joint mobility, range of motion, and functional activities; decreased
swelling and tenderness; and decreased duration of stiffness following prolonged
inactivity.
In clinical studies in which dosages were adjusted according to patient needs,
CLINORIL (sulindac) 200 to 400 mg daily was shown to be comparable in effectiveness to
aspirin 2400 to 4800 mg daily. CLINORIL (sulindac) was generally well tolerated, and patients
on it had a lower overall incidence of total adverse effects, of milder gastrointestinal
reactions, and of tinnitus than did patients on aspirin. (See ADVERSE REACTIONS.)
Rheumatoid arthritis
In patients with rheumatoid arthritis, the anti-inflammatory and analgesic
activity of CLINORIL (sulindac) was demonstrated by clinical measurements that included:
assessments by both patient and investigator of overall response; decrease in
disease activity as assessed by both patient and investigator; reduction in
overall joint pain; reduction in duration and severity of morning stiffness;
reduction in day and night pain; decrease in time required to walk 50 feet;
decrease in general pain as measured on a visual analog scale; improvement in
the Ritchie articular index; decrease in proximal interphalangeal joint size;
improvement in ARA Functional Class; increase in grip strength; reduction in
painful joint count and score; reduction in swollen joint count and score; and
increased flexion and extension of the wrist.
In clinical studies in which dosages were adjusted according to patient needs,
CLINORIL (sulindac) 300 to 400 mg daily was shown to be comparable in effectiveness to
aspirin 3600 to 4800 mg daily. CLINORIL (sulindac) was generally well tolerated, and patients
on it had a lower overall incidence of total adverse effects, of milder gastrointestinal
reactions, and of tinnitus than did patients on aspirin. (See ADVERSE REACTIONS.)
In patients with rheumatoid arthritis, CLINORIL (sulindac) may be used in combination
with gold salts at usual dosage levels. In clinical studies, CLINORIL (sulindac) added
to the regimen of gold salts usually resulted in additional symptomatic relief
but did not alter the course of the underlying disease.
Ankylosing spondylitis
In patients with ankylosing spondylitis, the anti-inflammatory and analgesic
activity of CLINORIL (sulindac) was demonstrated by clinical measurements that included:
assessments by both patient and investigator of overall response; decrease in
disease activity as assessed by both patient and investigator; improvement in
ARA Functional Class; improvement in patient and investigator evaluation of
spinal pain, tenderness and/or spasm; reduction in the duration of morning stiffness;
increase in the time to onset of fatigue; relief of night pain; increase in
chest expansion; and increase in spinal mobility evaluated by fingers-to-floor
distance, occiput to wall distance, the Schober Test, and the Wright Modification
of the Schober Test. In a clinical study in which dosages were adjusted according
to patient need, CLINORIL (sulindac) 200 to 400 mg daily was as effective as indomethacin
75 to 150 mg daily. In a second study, CLINORIL (sulindac) 300 to 400 mg daily was comparable
in effectiveness to phenylbutazone 400 to 600 mg daily. CLINORIL (sulindac) was better
tolerated than phenylbutazone. (See ADVERSE REACTIONS.)
Acute painful shoulder (Acute subacromial bursitis/supraspinatus tendinitis)
In patients with acute painful shoulder (acute subacromial bursitis/supraspinatus
tendinitis), the antiinflammatory and analgesic activity of CLINORIL (sulindac) was demonstrated
by clinical measurements that included: assessments by both patient and investigator
of overall response; relief of night pain, spontaneous pain, and pain on active
motion; decrease in local tenderness; and improvement in range of motion measured
by abduction, and internal and external rotation. In clinical studies in acute
painful shoulder, CLINORIL (sulindac) 300 to 400 mg daily and oxyphenbutazone 400 to 600
mg daily were shown to be equally effective and well tolerated.
Acute gouty arthritis
In patients with acute gouty arthritis, the anti-inflammatory and analgesic
activity of CLINORIL (sulindac) was demonstrated by clinical measurements that included:
assessments by both the patient and investigator of overall response; relief
of weight-bearing pain; relief of pain at rest and on active and passive motion;
decrease in tenderness; reduction in warmth and swelling; increase in range
of motion; and improvement in ability to function. In clinical studies, CLINORIL (sulindac)
at 400 mg daily and phenylbutazone at 600 mg daily were shown to be equally
effective. In these short-term studies in which reduction of dosage was permitted
according to response, both drugs were equally well tolerated.