General

Ketoprofen extended-release capsules contain ketoprofen. They differ only in their release characteristics. Ketoprofen capsules release drug in stomach whereas ketoprofen extended-release capsules are designed to resist dissolution in the low pH of gastric fluid but release drug at a controlled rate in the higher pH environment of the small intestine (see DESCRIPTION).

Irrespective of the pattern of release, the systemic availability (Fs) when either 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. The figure depicts the plasma time curves associated with both products.

Ketoprofen is > 99% bound to plasma proteins, mainly to albumin.

Separate sections follow which delineate differences between ketoprofen capsules and ketoprofen extended-release capsules.

Absorption

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

Ketoprofen extended-release capsules are also well-absorbed from this dosage form, although an observable increase in plasma levels does not occur until approximately 2 to 3 hours after taking the formulation. Peak plasma levels are usually reached 6 to 7 hours after dosing. (See Figure and Table, below).

When ketoprofen is administered with food, its total bioavailability (AUC) is not altered; however, the rate of absorption from either dosage form is slowed.

Ketoprofen capsules – Food intake reduces Cmax by approximately one-half and increases the mean time to peak concentration (tmax) 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 capsules.

Ketoprofen extended-release capsules – Administration of ketoprofen extended-release capsules with a high-fat meal causes a delay of about 2 hours in reaching the Cmax; neither the total bioavailability (AUC) nor the Cmax is affected. Circadian changes in the absorption process have not been studied.

The administration of antacids or other drugs which may raise stomach pH would not be expected to change the rate or extent of absorption of ketoprofen extended-release capsules.

Multiple Dosing

Steady-state concentrations of ketoprofen are attained within 24 hours after commencing treatment with ketoprofen extended-release capsules. In studies with healthy male volunteers, trough levels at 24 hours following administration of ketoprofen 200 mg extended-release capsules were 0.4 mg/L compared with 0.07 mg/L at 24 hours following administration of ketoprofen 50 mg capsules QID (12 hours), or 0.13 mg/L following administration of ketoprofen 75 mg capsules TID for 12 hours. Thus, relative to the peak plasma concentration, the accumulation of ketoprofen after multiple doses of ketoprofen extended-release 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 ketoprofen capsules or ketoprofen extended-release capsules.
 

KETOPROFEN PLASMA CONCENTRATIONS IN SUBJECTS RECEIVING 200 MG OF KETOPROFEN EXTENDED-RELEASE CAPSULES ONCE A DAY (QD), OR 50 MG OF KETOPROFEN CAPSULES EVERY 4 HOURS FOR 16 HOURS

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 CLINICAL PHARMACOLOGY: 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 h following administration of ketoprofen capsules, and 5.4 ± 2.2 h after administration of ketoprofen 200 mg extended-release 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.

After a single 200 mg dose of ketoprofen extended-release capsules, the plasma levels decline slowly, and average 0.4 mg/L after 24 hours (see Figure above).

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.

Elderly

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.

No studies have been conducted in patients with renal impairment taking ketoprofen extended-release capsules (see DOSAGE AND ADMINISTRATION).

Hepatically Impaired

For patients with alcoholic cirrhosis, no significant changes in the kinetic disposition of 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.

No studies have been conducted in patients with hepatic impairment taking ketoprofen extended-release capsules (see DOSAGE AND ADMINISTRATION).

Rheumatoid Arthritis and Osteoarthritis

The efficacy of ketoprofen has been demonstrated in patients with rheumatoid arthritis and osteoarthritis. Using standard assessments of therapeutic response, there were no detectable differences in effectiveness or in the incidence of adverse events in crossover comparison of ketoprofen capsules and ketoprofen extended-release capsules. 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 nonsteroidal drugs.

Management of Pain

The effectiveness of 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 capsules 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.

The use of ketoprofen extended-release capsules in patients with acute pain is not recommended, since, in comparison to ketoprofen capsules, ketoprofen extended-release capsules would be expected to have a delayed analgesic response due to its extended-release characteristics.

Cardiovascular Thrombotic Events

Clinical trials of several COX-2 selective and nonselective NSAIDs of up to three years duration have shown an increased risk of serious cardiovascular (CV) thrombotic events, including myocardial infarction (MI) and stroke, which can be fatal. Based on available data, it is unclear that the risk for CV thrombotic events is similar for all NSAIDs. The relative increase in serious CV thrombotic events over baseline conferred by NSAID use appears to be similar in those with and without known CV disease or risk factors for CV disease. However, patients with known CV disease or risk factors had a higher absolute incidence of excess serious CV thrombotic events, due to their increased baseline rate. Some observational studies found that this increased risk of serious CV thrombotic events began as early as the first weeks of treatment. The increase in CV thrombotic risk has been observed most consistently at higher doses.

To minimize the potential risk for an adverse CV event in NSAID-treated patients, use the lowest effective dose for the shortest duration possible. Physicians and patients should remain alert for the development of such events, throughout the entire treatment course, even in the absence of previous CV symptoms. Patients should be informed about the symptoms of serious CV events and the steps to take if they occur.

There is no consistent evidence that concurrent use of aspirin mitigates the increased risk of serious CV thrombotic events associated with NSAID use. The concurrent use of aspirin and an NSAID, such as ketoprofen, increases the risk of serious gastrointestinal (GI) events (see WARNINGS).

Status Post Coronary Artery Bypass Graft (CABG) Surgery

Two large, controlled clinical trials of a COX-2 selective NSAID for the treatment of pain in the first 10–14 days following CABG surgery found an increased incidence of myocardial infarction and stroke. NSAIDs are contraindicated in the setting of CABG (see CONTRAINDICATIONS).

Post-MI Patients

Observational studies conducted in the Danish National Registry have demonstrated that patients treated with NSAIDs in the post-MI period were at increased risk of reinfarction, CV-related death, and all-cause mortality beginning in the first week of treatment. In this same cohort, the incidence of death in the first year post MI was 20 per 100 person years in NSAID-treated patients compared to 12 per 100 person years in non-NSAID exposed patients. Although the absolute rate of death declined somewhat after the first year post-MI, the increased relative risk of death in NSAID users persisted over at least the next 4 years of follow-up.

Avoid the use of ketoprofen extended-release capsules in patients with a recent MI unless the benefits are expected to outweigh the risk of recurrent CV thrombotic events. If ketoprofen extended-release capsules are used in patients with a recent MI, monitor patients for signs of cardiac ischemia.

Hypertension

NSAIDs, including ketoprofen extended-release capsules, can lead to onset of new hypertension or worsening of pre-existing hypertension, either of which may contribute to the increased incidence of CV events. Patients taking thiazides or loop diuretics may have impaired response to these therapies when taking NSAIDs. NSAIDs, including ketoprofen extended-release capsules, should be used with caution in patients with hypertension. Blood pressure (BP) should be monitored closely during the initiation of NSAID treatment and throughout the course of therapy.

Heart Failure and Edema

The Coxib and traditional NSAID Trialists’ Collaboration meta-analysis of randomized controlled trials demonstrated an approximately two-fold increase in hospitalizations for heart failure in COX-2 selective-treated patients and nonselective NSAID-treated patients compared to placebo-treated patients. In a Danish National Registry study of patients with heart failure, NSAID use increased the risk of MI, hospitalization for heart failure, and death.

Additionally, fluid retention and edema have been observed in some patients treated with NSAIDs. Use of ketoprofen may blunt the CV effects of several therapeutic agents used to treat these medical conditions [e.g., diuretics, ACE inhibitors, or angiotensin receptor blockers (ARBs)] (see Drug Interactions).

Avoid the use of ketoprofen extended-release capsules in patients with severe heart failure unless the benefits are expected to outweigh the risk of worsening heart failure. If ketoprofen extended-release capsules are used in patients with severe heart failure, monitor patients for signs of worsening heart failure.

Risk of Ulceration, Bleeding, and Perforation

NSAIDs, including ketoprofen extended-release capsules, can cause serious gastrointestinal (GI) adverse events including inflammation, bleeding, ulceration, and perforation of the stomach, small intestine, or large intestine, which can be fatal. These serious adverse events can occur at any time, with or without warning symptoms, in patients treated with NSAIDs. Only one in five patients, who develop a serious upper GI adverse event on NSAID therapy, is symptomatic. Upper GI ulcers, gross bleeding, or perforation caused by NSAIDs occur in approximately 1% of patients treated for 3 to 6 months, and in about 2-4% of patients treated for one year. These trends continue with longer duration of use, increasing the likelihood of developing a serious GI event at some time during the course of therapy. However, even short-term therapy is not without risk.

NSAIDs should be prescribed with extreme caution in those with a prior history of ulcer disease or gastrointestinal bleeding. Patients with a prior history of peptic ulcer disease and/or gastrointestinal bleeding who use NSAIDs have a greater than 10-fold increased risk for developing a GI bleed compared to patients with neither of these risk factors. Other factors that increase the risk for GI bleeding in patients treated with NSAIDs include concomitant use of oral corticosteroids or anticoagulants, longer duration of NSAID therapy, smoking, use of alcohol, older age, and poor general health status. Most spontaneous reports of fatal GI events are in elderly or debilitated patients and therefore, special care should be taken in treating this population.

To minimize the potential risk for an adverse GI event in patients treated with an NSAID, the lowest effective dose should be used for the shortest possible duration. Patients and physicians should remain alert for signs and symptoms of GI ulceration and bleeding during NSAID therapy and promptly initiate additional evaluation and treatment if a serious GI adverse event is suspected. This should include discontinuation of the NSAID until a serious GI adverse event is ruled out. For high risk patients, alternate therapies that do not involve NSAIDs should be considered.

Advanced Renal Disease

No information is available from controlled clinical studies regarding the use of ketoprofen extended-release capsules in patients with advanced renal disease. Therefore, treatment with ketoprofen extended-release capsules is not recommended in these patients with advanced renal disease. If ketoprofen extended-release capsules therapy must be initiated, close monitoring of the patient’s renal function is advisable.

Premature Closure of Fetal Ductus Arteriosus

Avoid use of NSAIDs, including ketoprofen extended-release capsules, in pregnant women at about 30 weeks gestation and later. NSAIDs including ketoprofen extended-release capsules, increase the risk of premature closure of the fetal ductus arteriosus at approximately this gestational age.

Oligohydramnios/Neonatal Renal Impairment

Use of NSAIDs, including ketoprofen extended-release capsules, at about 20 weeks gestation or later in pregnancy may cause fetal renal dysfunction leading to oligohydramnios and, in some cases, neonatal renal impairment. These adverse outcomes are seen, on average, after days to weeks of treatment, although oligohydramnios has been infrequently reported as soon as 48 hours after NSAID initiation. Oligohydramnios is often, but not always, reversible with treatment discontinuation. Complications of prolonged oligohydramnios may, for example, include limb contractures and delayed lung maturation. In some postmarketing cases of impaired neonatal renal function, invasive procedures such as exchange transfusion or dialysis were required.

If NSAID treatment is necessary between about 20 weeks and 30 weeks gestation, limit ketoprofen extended-release capsules use to the lowest effective dose and shortest duration possible. Consider ultrasound monitoring of amniotic fluid if ketoprofen extended-release capsules treatment extends beyond 48 hours. Discontinue ketoprofen extended-release capsules if oligohydramnios occurs and follow up according to clinical practice (see PRECAUTIONS: Pregnancy).

Hepatic Effects

Borderline elevations of one or more liver tests may occur in up to 15% of patients taking NSAIDs including ketoprofen extended-release capsules. These laboratory abnormalities may progress, may remain unchanged, or may be transient with continuing therapy. Notable elevations of ALT or AST (approximately three or more times the upper limit of normal) have been reported in approximately 1% of patients in clinical trials with NSAIDs. In addition, rare cases of severe hepatic reactions, including jaundice and fatal fulminant hepatitis, liver necrosis and hepatic failure, some of them with fatal outcomes have been reported.

A patient with symptoms and/or signs suggesting liver dysfunction, or in whom an abnormal liver test has occurred, should be evaluated for evidence of the development of a more severe hepatic reaction while on therapy with ketoprofen extended-release capsules. If clinical signs and symptoms consistent with liver disease develop, or if systemic manifestations occur (e.g., eosinophilia, rash, etc.), ketoprofen extended-release capsules should be discontinued.

In patients with chronic liver disease with reduced serum albumin levels, ketoprofen’s pharmacokinetics are altered (see CLINICAL PHARMACOLOGY). Such patients should be closely monitored, and a reduction of dosage should be anticipated to avoid high blood levels of ketoprofen and/or its metabolites (see DOSAGE AND ADMINISTRATION).

Hematological Effects

Anemia is sometimes seen in patients receiving NSAIDs, including ketoprofen extended-release capsules. This may be due to fluid retention, occult or gross GI blood loss, or an incompletely described effect upon erythropoiesis. Patients on long-term treatment with NSAIDs, including ketoprofen extended-release capsules, should have their hemoglobin or hematocrit checked if they exhibit any signs or symptoms of anemia.

NSAIDs inhibit platelet aggregation and have been shown to prolong bleeding time in some patients. Unlike aspirin, their effect on platelet function is quantitatively less, of shorter duration, and reversible. Patients receiving ketoprofen extended-release capsules who may be adversely affected by alterations in platelet function, such as those with coagulation disorders or patients receiving anticoagulants, should be carefully monitored.

Preexisting Asthma

Patients with asthma may have aspirin-sensitive asthma. The use of aspirin in patients with aspirin-sensitive asthma has been associated with severe bronchospasm which can be fatal. Since cross reactivity, including bronchospasm, between aspirin and other nonsteroidal anti-inflammatory drugs has been reported in such aspirin-sensitive patients, ketoprofen extended-release capsules should not be administered to patients with this form of aspirin sensitivity and should be used with caution in patients with preexisting asthma.

ACE Inhibitors

Reports suggest that NSAIDs may diminish the antihypertensive effect of ACE-inhibitors. This interaction should be given consideration in patients taking NSAIDs concomitantly with ACE-inhibitors.

Antacids

Concomitant administration of magnesium hydroxide and aluminum hydroxide does not interfere with the rate or extent of the absorption of ketoprofen administered as the immediate-release capsules.

Aspirin

Ketoprofen does not alter aspirin absorption; however, in a study of 12 normal subjects, concurrent administration of aspirin decreased ketoprofen protein binding and increased ketoprofen plasma clearance from 0.07 L/kg/h without aspirin to 0.11 L/kg/h with aspirin. The clinical significance of these changes is not known; however, as with other NSAIDs, concomitant administration of ketoprofen and aspirin is not generally recommended because of the potential of increased adverse effects.

Diuretics

NSAIDs can reduce the natriuetic effect of furosemide and thiazides in some patients. Hydrochlorothiazide, given concomitantly with ketoprofen, produces a reduction in urinary potassium and chloride excretion compared to hydrochlorothiazide alone. Patients taking diuretics are at a greater risk of developing renal failure secondary to a decrease in renal blood flow caused by prostaglandin inhibition (see PRECAUTIONS). During concomitant therapy with NSAIDs, the patient should be observed closely for signs of renal failure (see WARNINGS: Renal Effects), as well as to assure diuretic efficacy.

Digoxin

In a study in 12 patients with congestive heart failure where ketoprofen and digoxin were concomitantly administered, ketoprofen did not alter the serum levels of digoxin.

Lithium

NSAIDs have produced an elevation of plasma lithium levels and a reduction in renal lithium clearance. The mean minimum lithium concentration increased 15% and the renal clearance was decreased by approximately 20%. These effects have been attributed to inhibition of renal prostaglandin synthesis by the NSAID. Thus, when NSAIDs and lithium are administered concurrently, subjects should be observed carefully for signs of lithium toxicity.

Methotrexate

Ketoprofen, like other NSAIDs, may cause changes in the elimination of methotrexate leading to elevated serum levels of the drug and increased toxicity. NSAIDs have been reported to competitively inhibit methotrexate accumulation in rabbit kidney slices. This may indicate that they could enhance the toxicity of methotrexate. Caution should be used when NSAIDs are administered concomitantly with methotrexate.

Probenecid

Probenecid increases both free and bound ketoprofen by reducing the plasma clearance of ketoprofen to about one-third, as well as decreasing its protein binding. Therefore, the combination of ketoprofen and probenecid is not recommended.

Warfarin

The effects of warfarin and NSAIDs on GI bleeding are synergistic, such that users of both drugs together have a risk of serious GI bleeding higher than users of either drug alone. In a short-term controlled study in 14 normal volunteers, ketoprofen did not significantly interfere with the effect of warfarin on prothrombin time. Bleeding from a number of sites may be a complication of warfarin treatment and GI bleeding a complication of ketoprofen treatment. Because prostaglandins play an important role in hemostasis and ketoprofen has an effect on platelet function as well (see PRECAUTIONS: Drug/Laboratory Test Interactions: Effect on Blood Coagulation), concurrent therapy with ketoprofen and warfarin requires close monitoring of patients on both drugs.

Effect on Blood Coagulation

Ketoprofen decreases platelet adhesion and aggregation. Therefore, it can prolong bleeding time by approximately 3 to 4 minutes from baseline values. There is no significant change in platelet count, prothrombin time, partial thromboplastin time, or thrombin time.

Risk Summary

Use of NSAIDs, including ketoprofen extended-release capsules, can cause premature closure of the fetal ductus arteriosus and fetal renal dysfunction leading to oligohydramnios and, in some cases, neonatal renal impairment. Because of these risks, limit dose and duration of ketoprofen extended-release capsules use between about 20 and 30 weeks of gestation, and avoid ketoprofen extended-release capsules use at about 30 weeks of gestation and later in pregnancy (see WARNINGS: Fetal Toxicity).

Clinical Considerations

Data