Ketoprofen

KETOPROFEN- ketoprofen capsule
Misemer Pharmaceuticals, Inc.

BOXED WARNING

Cardiovascular Thrombotic Events

  • Nonsteroidal anti-inflammatory drugs (NSAIDs) cause an increased risk of serious cardiovascular thrombotic events, including myocardial infarction and stroke, which can be fatal. This risk may occur early in treatment and may increase with duration of use.
  • Ketoprofen capsules are contraindicated in the setting of coronary artery bypass graft (CABG) surgery.


Gastrointestinal Risk

  • NSAIDs cause an increased risk of serious gastrointestinal adverse events including bleeding, ulceration, and perforation of the stomach or intestines, which can be fatal. These events can occur at any time during use and without warning symptoms. Elderly patients are at greater risk for serious gastrointestinal (GI) events.

1 Throughout this package insert, the term NSAID refers to a non-aspirin non-steroidal anti-inflammatory drug.

DESCRIPTION

Ketoprofen is a non-steroidal anti-inflammatory drug. The chemical name for ketoprofen is 2-(3-benzoylphenyl)-propionic acid with the following structural formula:

chemicalstructure

C 16 H 14 O 3 M.W. 254.29

It has a pKa of 5.94 in methanol: water (3:1) and an n-octanol: water partition coefficient of 0.97 (buffer pH 7.4).
Ketoprofen is a white or off-white, odorless, nonhygroscopic, fine to granular powder, melting at about 95°C. It is freely soluble in ethanol, chloroform, acetone, ether and soluble in benzene and strong alkali, but practically insoluble in water at 20°C.

Ketoprofen Capsules USP contain 25 mg, 50 mg or 75 mg of Ketoprofen USP for oral administration.

Inactive Ingredients
Drug Product
Colloidal silicon dioxide, lactose monohydrate, magnesium stearate, povidone, sodium starch glycolate.


Capsule Shell Constituents
25 mg: D&C yellow 10, edible printing ink, FD&C blue 1, FD&C yellow 6, gelatin, sodium lauryl
sulfate, and titanium dioxide.
50 mg: D&C yellow 10, edible printing ink, FD&C green 3, gelatin, sodium lauryl sulfate, and
titanium dioxide.
75 mg: Edible printing ink, gelatin, sodium lauryl sulfate and titanium dioxide.

CLINICAL PHARMACOLOGY

Ketoprofen is a non-steroidal anti-inflammatory drug with analgesic and antipyretic properties.
The anti-inflammatory, analgesic and antipyretic properties of ketoprofen have been demonstrated in classical animal and in vitro test systems. In anti-inflammatory models ketoprofen has been shown to have inhibitory effects on prostaglandin and leukotriene synthesis, to have antibradykinin activity, as well as to have lysosomal membrane-stabilizing action. However, its mode of action, like that of other non-steroidal anti-inflammatory drugs, is not fully understood.

Pharmacodynamics
Ketoprofen is a racemate with only the S enantiomer possessing pharmacological activity. The enantiomers have similar concentration time curves and do not appear to interact with one another.
An analgesic effect-concentration relationship for ketoprofen was established in an oral surgery pain study with immediate-release ketoprofen capsules. The effect-site rate constant (k e0 ) was estimated to be 0.9 hour (95% confidence limits: 0 to 2.1), and the concentration (C e50 ) of ketoprofen that produced one-half the maximum PID (pain intensity difference) was 0.3 mcg/mL (95% confidence limits: 0.1 to 0.5). Thirty-three (33) to 68% of patients had an onset of action (as measured by reporting some pain relief) within 30 minutes following a single oral dose in postoperative pain and dysmenorrhea studies. Pain relief (as measured by remedication) persisted for up to 6 hours in 26 to 72% of patients in these studies.

Pharmacokinetics
General
The systemic availability (FS) when the oral formulation is compared with IV administration is approximately 90% in humans. For 75 to 200 mg single doses, the area under the curve has been shown to be dose proportional.
Ketoprofen is > 99% bound to plasma proteins, mainly to albumin.

Absorption
Ketoprofen is rapidly and well-absorbed, with peak plasma levels occurring within 0.5 to 2 hours.

When ketoprofen is administered with food, its total bioavailability (AUC) is not altered; however, the rate of absorption is slowed.
Food intake reduces C max by approximately one-half and increases the mean time to peak concentration (t max ) from 1.2 hours for fasting subjects (range, 0.5 to 3 hours) to 2.0 hours for fed subjects (range, 0.75 to 3 hours). The fluctuation of plasma peaks may also be influenced by circadian changes in the absorption process.
Concomitant administration of magnesium hydroxide and aluminum hydroxide does not interfere with absorption of ketoprofen from ketoprofen capsules.
Multiple Dosing
Steady-state concentrations of ketoprofen are attained within 24 hours after commencing treatment with immediate-release ketoprofen capsules. In studies with healthy male volunteers, trough levels at 24 hours following administration of immediate-release ketoprofen 50 mg capsules QID for 12 hours were 0.07 mg/L and 0.13 mg/L at 24 hours following administration of immediate-release ketoprofen 75 mg capsules TID for 12 hours. Thus, relative to the peak plasma concentration, the accumulation of ketoprofen after multiple doses of immediate-release ketoprofen capsules is minimal.
The figure below shows a reduction in peak height and area after the second 50 mg dose. This is probably due to a combination of food effects, circadian effects, and plasma sampling times. It is unclear to what extent each factor contributes to the loss of peak height and area. The shaded area represents ± 1 standard deviation (S.D.) around the mean for immediate-release ketoprofen capsules.

image1
(click image for full-size original)

KETOPROFEN PLASMA CONCENTRATIONS IN SUBJECTS RECEIVING KETOPROFEN CAPSULES 50 MG EVERY 4 HOURS FOR 16 HOURS

image2
(click image for full-size original)

Metabolism
The metabolic fate of ketoprofen is glucuronide conjugation to form an unstable acyl-glucuronide. The glucuronic acid moiety can be converted back to the parent compound. Thus, the metabolite serves as a potential reservoir for parent drug, and this may be important in persons with renal insufficiency, whereby the conjugate may accumulate in the serum and undergo deconjugation back to the parent drug (see Special Populations , Renally Impaired). The conjugates are reported to appear only in trace amounts in plasma in healthy adults, but are higher in elderly subjects-presumably because of reduced renal clearance. It has been demonstrated that in elderly subjects following multiple doses (50 mg every 6 h), the ratio of conjugated to parent ketoprofen AUC was 30% and 3%, respectively, for the S & R enantiomers.
There are no known active metabolites of ketoprofen. Ketoprofen has been shown not to induce drug-metabolizing enzymes.

Elimination
The plasma clearance of ketoprofen is approximately 0.08 L/kg/h with a Vd of 0.1 L/kg after IV administration. The elimination half-life of ketoprofen has been reported to be 2.05 ± 0.58 h (Mean ± S.D.) following IV administration from 2 to 4 hours following administration of ketoprofen capsules. In cases of slow drug absorption, the elimination rate is dependent on the absorption rate and thus t1/2 relative to an IV dose appears prolonged.
In a 24 hour period, approximately 80% of an administered dose of ketoprofen is excreted in the urine, primarily as the glucuronide metabolite.

Enterohepatic recirculation of the drug has been postulated, although biliary levels have never been measured to confirm this.

Special Populations
Elderly
Clearance and unbound fraction
The plasma and renal clearance of ketoprofen is reduced in the elderly (mean age, 73 years) compared to a younger normal population (mean age, 27 years). Hence, ketoprofen peak concentration and AUC increase with increasing age. In addition, there is a corresponding increase in unbound fraction with increasing age. Data from one trial suggest that the increase is greater in women than in men. It has not been determined whether age-related changes in absorption among the elderly contribute to the changes in bioavailability of ketoprofen.
In a study conducted with young and elderly men and women, results for subjects older than 75 years of age showed that free drug AUC increased by 40% and Cmax increased by 60% as compared with estimates of the same parameters in young subjects (those younger than 35 years of age;.
Also in the elderly, the ratio of intrinsic clearance/availability decreased by 35% and plasma half-life was prolonged by 26%. This reduction is thought to be due to a decrease in hepatic extraction associated with aging.
Renally Impaired
Studies of the effects of renal-function impairment have been small. They indicate a decrease in clearance in patients with impaired renal function. In 23 patients with renal impairment, free ketoprofen peak concentration was not significantly elevated, but free ketoprofen clearance was reduced from 15 L/kg/h for normal subjects to 7 L/kg/h in patients with mildly impaired renal function, and to 4 L/kg/h in patients with moderately to severely impaired renal function. The elimination t1/2 was prolonged from 1.6 hours in normal subjects to approximately 3 hours in patients with mild renal impairment, and to approximately 5 to 9 hours in patients with moderately to severely impaired renal function.
Hepatically Impaired
For patients with alcoholic cirrhosis, no significant changes in the kinetic disposition of immediate-release ketoprofen capsules were observed relative to age-matched normal subjects: the plasma clearance of drug was 0.07 L/kg/h in 26 hepatically impaired patients. The elimination half-life was comparable to that observed for normal subjects. However, the unbound (biologically active) fraction was approximately doubled, probably due to hypoalbuminemia and high variability which was observed in the pharmacokinetics for cirrhotic patients. Therefore, these patients should be carefully monitored and daily doses of ketoprofen kept at the minimum providing the desired therapeutic effect.

Clinical Trials
Rheumatoid Arthritis and Osteoarthritis
The efficacy of ketoprofen has been demonstrated in patients with rheumatoid arthritis and osteoarthritis. In other trials, ketoprofen demonstrated effectiveness comparable to aspirin, ibuprofen, naproxen, piroxicam, diclofenac, and indomethacin. In some of these studies there were more dropouts due to gastrointestinal side effects among patients on ketoprofen than among patients on other NSAIDs.
In studies with patients with rheumatoid arthritis, ketoprofen was administered in combination with gold salts, antimalarials, low-dose methotrexate, d-penicillamine, and/or corticosteroids with results comparable to those seen with control non-steroidal drugs.

Management of Pain
The effectiveness of immediate-release ketoprofen capsules as a general-purpose analgesic has been studied in standard pain models which have shown the effectiveness of doses of 25 to 150 mg. Doses of 25 mg were superior to placebo. Doses larger than 25 mg generally could not be shown to be significantly more effective, but there was a tendency toward faster onset and greater duration of action with 50 mg, and, in the case of dysmenorrhea, a significantly greater effect overall with 75 mg. Doses greater than 50 to 75 mg did not have increased analgesic effect. Studies in postoperative pain have shown that ketoprofen in doses of 25 to 100 mg was comparable to 650 mg of acetaminophen with 60 mg of codeine, or 650 mg of acetaminophen with 10 mg of oxycodone. Ketoprofen tended to be somewhat slower in onset; peak pain relief was about the same and the duration of the effect tended to be 1 to 2 hours longer, particularly with the higher doses of ketoprofen.

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