ARTHROTEC (diclofenac sodium, misoprostol)

ARTHROTEC (diclofenac sodium plus misoprostol) is indicated for the following:

• Acute and chronic use in the relief of the signs and symptoms of rheumatoid arthritis and osteoarthritis.

Throughout this document, the term NSAIDs refers to both non-selective NSAIDs and selective COX-2 inhibitor NSAIDs, unless otherwise indicated.

Diclofenac, particularly at higher doses, is associated with an increased risk of serious cardiovascular related adverse events that is comparable to COX-2 inhibitors and high dose ibuprofen. For patients with pre-existing risk factors for cardiovascular disease (including ischemic heart disease, cerebrovascular disease and/or congestive heart failure NYHA II-IV) other management strategies that do not include NSAlDs, particularly COX-2 inhibitors, ibuprofen and diclofenac, should be considered first (see CONTRAINDICATIONS and WARNINGS AND PRECAUTIONS).

For patients with increased risk of developing GI adverse events other management strategies that do not include NSAlDs should be considered first (see CONTRAINDICATIONS and WARNINGS AND PRECAUTIONS).

Use of ARTHROTEC should be limited to the lowest effective dose for the shortest possible duration of treatment in order to minimize the potential risk for cardiovascular or gastrointestinal adverse events (see CONTRAINDICATIONS and WARNINGS AND PRECAUTIONS).

ARTHROTEC, as a NSAID, does NOT treat clinical disease or prevent its progression.
ARTHROTEC, as a NSAID, only relieves symptoms and decreases inflammation for as long as the patient continues to take it.

Geriatrics (>65 years of age):
Evidence from clinical studies and postmarket experience suggests that use in geriatric patients is associated with differences in safety or effectiveness (see WARNINGS AND PRECAUTIONS)

Pediatrics (<18 years of age):
Not recommended for pediatric use (see CONTRAINDICATIONS).

General

Frail or debilitated patients may tolerate side effects less well and therefore special care should be taken in treating this population. To minimize the potential risk for an adverse event, the lowest effective dose should be used for the shortest possible duration. As with other NSAIDs, caution should be used in the treatment of elderly patients who are more likely to be suffering from impaired renal, hepatic or cardiac function. For high risk patients, alternate therapies that do not involve NSAIDs should be considered.

The use of diclofenac/misoprostol is NOT recommended for use with other NSAIDs, with the exception of low-dose ASA for cardiovascular prophylaxis, because of the absence of any evidence demonstrating synergistic benefits and the potential for additive adverse reactions including gastrointestinal ulcers and bleeding (see DRUG INTERACTIONS – Drug-Drug Interactions – Acetylsalicylic acid (ASA) or other NSAIDs).

In common with other anti-inflammatory drugs, ARTHROTEC may mask the usual signs of infection, such as fever.

Carcinogensis and Mutagenesis

(See TOXICOLOGY)

Cardiovascular

Diclofenac is associated with an increased risk of serious cardiovascular (CV) thrombotic events (such as myocardial infarction and stroke), which can be fatal. The increased risk is comparable to COX-2 inhibitors and high-dose ibuprofen. An increased risk of CV serious thrombotic events may occur early in the treatment and become higher with the duration of treatment. The risk may increase with the dose. Patients with CV disease or CV risk factors may be at greater risk.

Meta-analyses of randomized clinical trials comparing several different NSAIDs suggest that diclofenac, particularly at higher doses, is associated with an increased risk of cardiovascular adverse events that is comparable to COX-2 inhibitors and high dose ibuprofen. Large population-based observational studies conducted in the general population also support these findings. Some observational studies showed that the increased risk of the CV thrombotic events began as early as the first weeks of treatment. Such risk increased with duration of NSAID treatment. The relative increase in risk of serious CV thrombotic events during NSAID treatment appears to be similar in patients with or without CV disease or CV risk factors. However, patients with CV disease or CV risk factors during the treatment had a higher absolute risk of serious CV thrombotic events due to their increased baseline rate.

As the cardiovascular risks of diclofenac may increase with dose and duration of exposure, the lowest effective daily dose should be used for the shortest duration possible. The patient's need for symptomatic relief and response to therapy should be re-evaluated periodically.

Patients should remain alert for the signs and symptoms of serious arteriothrombotic events (e.g. chest pain, shortness of breath, weakness, slurring of speech), which can occur without warnings. Patients should be instructed to see a physician immediately in case of such an event.

Use of NSAIDs, such as ARTHROTEC, can lead to new hypertension or can worsen pre-existing hypertension, either of which may increase the risk of cardiovascular events as described below. Thus blood pressure should be monitored regularly. Consideration should be given to discontinuing ARTHROTEC should hypertension either develop or worsen with its use.

Use of NSAIDs, such as ARTHROTEC, can induce fluid retention and edema, and may exacerbate congestive heart failure, through a renally-mediated mechanism. (See Warnings and Precautions - Renal - Fluid and Electrolyte Balance).

Caution should be exercised in prescribing ARTHROTEC to patients with risk factors for cardiovascular disease, cerebrovascular disease or renal disease, such as any of the following (NOT an exhaustive list):

• Hypertension
• Dyslipidemia / Hyperlipidemia
• Diabetes Mellitus
• Congestive Heart Failure (NYHA II-IV)
• Ischemic heart disease
• Peripheral Arterial Disease
• Smoking
• Creatinine Clearance < 60 mL/min or 1 mL/sec
• Acute myocardial infarction, history of myocardial infarction and/or angina
• Stroke, cerebrovascular accident, transient ischemic attacks, and/or amaurosis fugax

If needed, these patients should be treated only after careful consideration (See WARNINGS AND PRECAUTIONS BOX).

Endocrine and Metabolism

With nonsteroidal anti-inflammatory treatment there is a potential risk of hyperkalemia, particularly in patients with conditions such as diabetes mellitus or renal failure; elderly patients; or in patients receiving concomitant therapy with beta-adrenergic blockers, angiotensin converting enzyme inhibitors or some diuretics. Serum electrolytes should be monitored periodically during long-term therapy, especially in those patients who are at risk.

Corticosteroids:
ARTHROTEC (diclofenac sodium plus misoprostol) is NOT a substitute for corticosteroids. It does NOT treat corticosteroid insufficiency. Abrupt discontinuation of corticosteroids may lead to exacerbation of corticosteroid-responsive illness. Patients on prolonged corticosteroid therapy should have their therapy tapered slowly if a decision is made to discontinue corticosteroids (see DRUG INTERACTIONS – Drug-Drug Interactions – Glucocorticoids).

Gastrointestinal (GI)

The presence of misoprostol in the product may protect against the mucosal damaging effects of the other component, diclofenac.

However, serious GI toxicity, such as peptic/duodenal ulceration, inflammation, perforation, obstruction and gastrointestinal bleeding, sometimes severe and occasionally fatal can occur at any time, with or without symptoms in patients treated with NSAIDs including ARTHROTEC (diclofenac sodium plus misoprostol). NSAIDs, including ARTHROTEC, should be used with caution in patients with a history of, or active, GI disease, such as ulceration, bleeding, or inflammatory conditions. 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, the lowest effective dose should be used for the shortest possible duration. For high risk patients, alternate therapies that do not involve NSAIDs should be considered (see WARNINGS AND PRECAUTIONS – Special Populations – Geriatrics).

Minor upper GI problems, such as dyspepsia, commonly occur at any time. Physicians should remain alert for ulceration and bleeding in patients treated with nonsteroidal anti-inflammatory drugs, even in the absence of previous GI tract symptoms.

Physicians should inform patients about the signs and/or symptoms of serious GI toxicity and instruct them to discontinue using ARTHROTEC and seek emergency medical attention if they experience any such symptoms. Because serious GI tract ulceration and bleeding can occur without warning symptoms, physicians should follow chronically treated patients by checking their hemoglobin periodically and by being vigilant for the signs and symptoms of ulceration and bleeding.

The utility of periodic laboratory monitoring has NOT been demonstrated, nor has it been adequately assessed. Most patients who develop a serious upper GI adverse event on NSAID therapy have no symptoms. Upper GI ulcers, gross bleeding or perforation, caused by NSAIDs, appear to occur in approximately 1% of patients treated for 3-6 months, and in about 2-4% of patients treated for one year. These trends continue, thus increasing the likelihood of developing a serious GI event at some time during the course of therapy. Even short-term therapy has its risks.

Caution should be taken if prescribing ARTHROTEC to patients with a prior history of peptic / duodenal ulcer disease or gastrointestinal bleeding as these individuals have a greater than 10-fold higher risk for developing a GI bleed when taking a NSAID than patients with neither of these risk factors. Other risk factor for GI ulceration and bleeding include the following: Helicobacter pylori infection, increased age, prolonged use of NSAID therapy, excess alcohol intake, smoking, female gender, poor general health status or concomitant therapy with any of the following:

• Anti-coagulants (e.g. warfarin)
• Anti-platelet agents (e.g. ASA, clopidogrel)
• Oral corticosteroids (e.g. prednisone)
• Selective Serotonin Reuptake Inhibitors (SSRIs) (e.g. citalopram, fluoxetine, paroxetine, sertraline)

If ulceration is suspected or confirmed, or if GI bleeding occurs, ARTHROTEC should be discontinued immediately, appropriate treatment instituted and the patient monitored closely.
No studies, to date, have identified any group of patients not at risk of developing ulceration and bleeding. Studies to date show that all NSAIDs can cause GI tract adverse events. Although existing data do not clearly identify differences in risk between various NSAIDs, this may be shown in the future.

Genitourinary

Some NSAIDs are associated with persistent urinary symptoms (bladder pain, dysuria, urinary frequency), hematuria or cystitis. The onset of these symptoms may occur at any time after the initiation of therapy with an NSAID. Some cases have become severe on continued treatment. Should urinary symptoms occur, in the absence of an alternate explanation, treatment with ARTHROTEC (diclofenac sodium plus misoprostol) must be stopped to ascertain if symptoms disappear. This should be done before any urological investigations or treatments are carried out.

Post-menopausal vaginal bleeding may be related to ARTHROTEC administration. If this occurs, diagnostic workup should be undertaken to rule out gynecological pathology (see ADVERSE DRUG REACTIONS).

Hematologic

NSAIDs inhibiting prostaglandin biosynthesis interfere with platelet function to varying degrees; patients who may be adversely affected by such an action, such as those on anti-coagulants or suffering from haemophilia or platelet disorders should be carefully monitored when ARTHROTEC is administered.

Anti-coagulants:
The concomitant use of NSAIDs, including diclofenac/misoprostol, with anticoagulants increases the risk of GI and non-GI bleeding and should be given with caution. Concurrent therapy of ARTHROTEC with anticoagulants requires close monitoring of anticoagulation (see DRUG INTERACTIONS).

Even with therapeutic INR monitoring, increased bleeding may occur.

Anti-platelet Effects:
NSAIDs inhibit platelet aggregation and have been shown to prolong bleeding time in some patients. Unlike acetylsalicyclic acid (ASA), their effect on platelet function is quantitatively less, or of shorter duration, and is reversible. Misoprostol does not exacerbate the effects of diclofenac on platelet activity.

ARTHROTEC and other NSAIDs have no proven efficacy as anti-platelet agents and should NOT be used as a substitute for ASA or other anti-platelet agents for prophylaxis of cardiovascular thromboembolic diseases. Anti-platelet therapies (e.g. ASA) should NOT be discontinued. There is some evidence that use of NSAIDs with ASA can markedly attenuate the cardioprotective effects of ASA (see DRUG INTERACTIONS – Drug-Drug Interactions – Acetylsalicylic Acid (ASA) or other NSAIDs).

Concomitant administration of ARTHROTEC with low dose ASA increases the risk of GI ulceration and associated complications.

Blood dyscrasias:
Cases of agranulocytosis and hemolytic anemia, some serious, were identified in patients taking diclofenac sodium or diclofenac/misoprostol.

Other blood dyscrasias (such as neutropenia, leucopenia, thrombocytopenia, aplastic anemia) associated with the use of NSAIDs are rare, but could occur with severe consequences.

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

Hepatic/Biliary/Pancreatic

As with other NSAIDs, including ARTHROTEC, borderline elevations of one or more liver function tests (AST, ALT, alkaline phosphatase) may occur in up to 15% of patients. These abnormalities may progress, may remain essentially unchanged, or may be transient with continued therapy. In clinical trials of 4 to 12 weeks duration, clinically significant (>3 times the upper limit of normal) elevations of SGPT (ALT) and/or SGOT (AST), were observed in 2.5% or less of patients who received diclofenac/misoprostol or diclofenac/placebo. In a large trial where patients received diclofenac for a mean of 18 months, ALT/AST elevations >3xULN were observed in 3.1% of patients and elevations >5xULN were observed in 1.3% of patients. ALT/AST elevations usually occur within 1-6 months. However, clinically important liver events, resulting in hospitalization, occurred at various times during the study, and not necessarily early in the course of therapy. Furthermore, more meaningful elevations in transaminases were detected before patients became symptomatic due to routine testing during the trial (see Monitoring and Laboratory testing).

In postmarketing reports of patients receiving diclofenac, cases of drug-induced hepatotoxicity have been reported in the first month, and in some cases, the first 2 months of therapy, but can occur at any time during the treatment. 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 more severe hepatic reaction while on therapy with this drug. Postmarketing surveillance has reported cases of severe hepatic reactions including jaundice, fulminant hepatitis with and without jaundice, liver necrosis and hepatic failure. Some of these cases have resulted in fatalities or liver transplantation.

Physicians should measure transaminases periodically in patients receiving ARTHROTEC because severe hepatotoxicity may develop without a prodrome of distinguishing symptoms. Severe hepatic reactions can occur at any time during treatment with diclofenac. Although such reactions are rare, if abnormal liver function tests persist or worsen, if clinical signs and symptoms consistent with liver disease develop (e.g. jaundice), or if systemic manifestations occur (e.g. eosinophilia, rash, etc.), this drug should be discontinued immediately.

To minimize the possibility that hepatic injury will become severe between transaminase measurements, physicians should inform patients of the warning signs and symptoms of hepatotoxicity (e.g. nausea, fatigue, lethargy, diarrhea, pruritus, jaundice, right upper quadrant tenderness, and «flu-like» symptoms), and the appropriate action patients should take if these signs and symptoms appear. Use of ARTHROTEC is contraindicated in patients with significant hepatic impairment or active liver disease. If there is a need to prescribe this drug in the presence of all other patients with liver impairment, it must be done under strict observation.

Caution is advised when using ARTHROTEC in patients with hepatic porphyria, since ARTHROTEC may trigger an attack.

Hypersensitivity Reactions

Anaphylactoid Reactions:
As with NSAIDs in general, anaphylactoid reactions have occurred in patients without known prior exposure to ARTHROTEC. In post-marketing experience, rare cases of anaphylactic/anaphylactoid reactions and angioedema have been reported in patients receiving ARTHROTEC. ARTHROTEC should NOT be given to patients with the ASA-triad. This symptom complex typically occurs in asthmatic patients who experience rhinitis with or without nasal polyps, or who exhibit severe, potentially fatal bronchospasm after taking ASA or other NSAIDs (see CONTRAINDICATIONS).

ASA-Intolerance:
ARTHROTEC should NOT be given to patients with complete or partial syndrome of ASA-intolerance (rhinosinusitis, urticaria/angioedema, nasal polyps, asthma) in whom asthma, anaphylaxis, urticaria/angioedema, rhinitis or other allergic manifestations are precipitated by ASA or other NSAIDs. Fatal anaphylactoid reactions have occurred in such individuals. As well, individuals with the above medical problems are at risk of a severe reaction even if they have taken NSAIDs in the past without any adverse reaction (see CONTRAINDICATIONS).

Cross-sensitivity:
Patients sensitive to one NSAID may be sensitive to any of the other NSAIDs as well.

Serious skin reactions:
(See WARNINGS AND PRECAUTIONS – Skin)

Immune

(See WARNINGS AND PRECAUTIONS – Infection – Aseptic Meningitis)

Infection

ARTHROTEC, in common with other NSAIDs, may mask signs and symptoms of an underlying infections disease.

Aseptic Meningitis:
Rarely, with some NSAIDs, the symptoms of aseptic meningitis (stiff neck, severe headaches, nausea and vomiting, fever or clouding of consciousness) have been observed. Patients with autoimmune disorders (systemic lupus erythematosus, mixed connective tissue diseases, etc.) seem to be pre-disposed. Therefore, in such patients, the health care provider must be vigilant to the development of this complication.

Neurologic

Some patients may experience drowsiness, dizziness, blurred vision, vertigo, tinnitus, hearing loss, insomnia or depression with the use of NSAIDs such as ARTHROTEC. If patients experience these side effects, they should exercise caution in carrying out activities that require alertness.

Ophthalmologic

Blurred, diminished vision, and/or sensitivity to light have been reported with the use of NSAIDs. If such symptoms develop, ARTHROTEC should be discontinued and an ophthalmologic examination performed; ophthalmologic examination should be carried out at periodic intervals in any patient receiving ARTHROTEC for an extended period of time.

Peri-Operative Considerations

(See CONTRAINDICATIONS – Coronary Artery Bypass Graft Surgery)

Psychiatric

Some patients may experience depression with the use of diclofenac (see WARNINGS AND PRECAUTIONS –Neurologic).

Renal

Long-term administration of nonsteroidal anti-inflammatory drugs to animals has resulted in renal papillary necrosis and other abnormal renal pathology. In humans, there have been reports of acute interstitial, nephritis, hematuria, low grade proteinuria, and occasionally nephrotic syndrome.

Renal insufficiency due to NSAID use is seen in patients with prerenal conditions leading to the reduction in renal blood flow or blood volume. Under these circumstances, renal prostaglandins help maintain renal perfusion and glomerular filtration rate (GFR). In these patients, administration of a NSAID may cause a reduction in prostaglandin formation and may precipitate overt renal decompensation. Patients at greatest risk of this reaction are those with pre-existing renal insufficiency (GFR<60 mL/min or 1 mL/s), dehydrated patients, patients on salt-restricted diets, heart failure, cirrhosis, liver dysfunction, those taking angiotensin-converting enzyme inhibitors, angiotensin-II receptor blockers, cyclosporin, diuretics, and the elderly. Serious or life-threatening renal failure has been reported in patients with normal or impaired renal function after short term therapy with NSAIDs. Even patients at risk who demonstrated the ability to tolerate a NSAID under stable conditions may decompensate during periods of added stress (e.g. dehydration due to gastroenteritis). Discontinuation of NSAIDs is usually followed by recovery to the pre-treatment state.

Diclofenac and its metabolites are eliminated primarily by the kidneys, therefore ARTHROTEC should be used with great caution in patients with impaired renal function. In these cases, utilization of lower doses of diclofenac should be considered and patients carefully monitored. Caution should be used when initiating treatment with NSAIDs, such as ARTHROTEC, in patients with dehydration. It is advisable to rehydrate patients first and then start therapy. The dose should be kept as low as possible and renal function should be monitored.
During long-term therapy kidney function should be monitored periodically.

Advanced Renal Disease:
(See CONTRAINDICATIONS)

Fluid and Electrolyte Balance:
Use of NSAIDs, such as ARTHROTEC, can promote sodium retention in a dose-dependent manner, which can lead to fluid retention and edema, and consequences of increased blood pressure and exacerbation of congestive heart failure. Thus, caution should be exercised in prescribing ARTHROTEC in patients with a history of congestive heart failure, compromised cardiac function, hypertension, increased age or other conditions predisposing to fluid retention (see WARNINGS AND PRECAUTIONS – Cardiovascular).

Use of NSAIDs, such as ARTHROTEC, can increase the risk of hyperkalemia, especially in patients with diabetes mellitus, renal failure, increased age, or those receiving concomitant therapy with adrenergic blockers, angiotensin-converting enzyme inhibitors, angiotensin-II receptor antagonists, cyclosporin, or some diuretics.

Electrolytes should be monitored periodically (see CONTRAINDICATIONS).

Respiratory

ASA-induced asthma is an uncommon but very important indication of ASA and NSAID sensitivity. It occurs more frequently in patients with asthma who have nasal polyps.

Sexual Function / Reproduction

The use of ARTHROTEC, as with any drug known to inhibit cyclooxygenase/ prostaglandin synthesis, may impair fertility and is not recommended in women attempting to conceive. Therefore, in women who have difficulties conceiving, or who are undergoing investigation of infertility, withdrawal of ARTHROTEC should be considered.

Skin

In rare cases, serious skin reactions such as Stevens-Johnson syndrome, toxic epidermal necrolysis, exfoliative dermatitis and erythema multiforme have been associated with the use of some NSAIDs. Because the rate of these reactions is low, they have usually been noted during post-marketing surveillance in patients taking other medications also associated with the potential development of these serious skin reactions. Thus, causality is NOT clear. These reactions are potentially life-threatening but may be reversible if the causative agent is discontinued and appropriate treatment instituted. Patients should be advised that if they experience a skin rash they should discontinue their NSAID and contact their physician for assessment and advice, including which additional therapies to discontinue.

Serious skin reactions, some of them fatal, including drug reaction with eosinophilia and systemic symptoms (DRESS syndrome), exfoliative dermatitis, Stevens-Johnson syndrome, and toxic epidermal necrolysis, have been reported very rarely in association with the use of NSAIDs, including ARTHROTEC (see ADVERSE REACTIONS - Post-Market Adverse Drug Reactions). Patients appear to be at higher risk for these events early in the course of therapy: the onset of the event occurring in the majority of cases within the first month of treatment. ARTHROTEC should be discontinued at the first appearance of skin rash, mucosal lesions, or any other sign of hypersensitivity.

ARTHROTEC may cause sensitivity to sunlight. Any exposure to sunlight or sunlamps may cause sunburn, skin blisters, skin rash, redness, itching or discoloration. Patients should be advised that if they experience any of these symptoms, they should discontinue their NSAID and contact their physician for assessment and advice, including which additional therapies to discontinue.

Special Populations

Pregnant Women:
ARTHROTEC is CONTRAINDICATED for use in women who are pregnant, or in whom pregnancy has not been excluded. Misoprostol administration to pregnant women induces uterine contractions and is associated with abortion, premature birth, birth defects and fetal death. Misoprostol can cause uterine tetany and uterine rupture if administered to pregnant women beyond the eighth week of pregnancy (see CONTRAINDICATIONS and ADVERSE REACTIONS – Post-Market Adverse Drug Reactions).

Inhibition of prostaglandin synthesis may adversely affect pregnancy and/or the embryo-foetal development. Data from epidemiological studies suggest an increased risk of miscarriage and of cardiac malformation after use of a prostaglandin synthesis inhibitor in early pregnancy.

NSAIDs including diclofenac may result in reduction of amniotic fluid volume and even oligohydramnios. Such effects may occur within a few days after treatment initiation and are usually reversible. The rate of oligohydramnios after treatment with some NSAIDs for 2 to 8 weeks was reported as high as 38% or even higher. NSAIDs were also shown to cause significant reduction in fetal urine production prior to reduction of amniotic fluid volume.

In animals, administration of a prostaglandin synthesis inhibitor has been shown to result in increased pre-and post-implantation loss and embryo-foetal lethality. In addition, increased incidences of various malformations, including cardiovascular, have been reported in animals given a prostaglandin synthesis inhibitor during the organogenetic period.

Nursing Women:
Misoprostol is rapidly metabolised in the mother to misoprostol acid, which is biologically active and is excreted in breast milk. Diclofenac/misoprostol is contraindicated in nursing mothers because the excretion of misoprostol acid could cause undesirable effects such as diarrhea in nursing infants (see CONTRAINDICATIONS).

Pediatrics (<18 years of age):
(See CONTRAINDICATIONS)

Geriatrics (>65 years of age):
Patients older than 65 years and frail or debilitated patients are most susceptible to a variety of adverse reactions from NSAIDs. The incidence of these adverse reactions increases with dose and duration of treatment. In addition, these patients are less tolerant to ulceration and bleeding. Most reports of fatal GI events are in this population. Older patients are also at risk of lower esophageal ulceration and bleeding (see ACTION AND CLINICAL PHARMACOLOGY). For such patients, consideration should be given to a starting dose lower than the one usually recommended, with individual adjustment when necessary and under close supervision. As with any NSAID, the elderly are likely to tolerate adverse events less well than younger patients.

Diclofenac is known to be substantially excreted by the kidney, and the risk of toxic reactions to ARTHROTEC may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function (see WARNINGS AND PRECAUTIONS – Renal).

Monitoring and Laboratory Tests

Cardiovascular (Hypertension): Blood pressure should be monitored regularly during therapy with ARTHROTEC.

Hematologic: Patients on long-term treatment with NSAIDs, including ARTHROTEC, should have their hemoglobin, hematocrit, red blood cells, white blood cells, and platelets checked if they exhibit any signs or symptoms of anemia or blood loss or blood dyscrasia.

Concurrent therapy of ARTHROTEC with warfarin requires close monitoring of the international normalized ratio (INR).

Hepatic: Hepatic functions (e.g. serum transaminases, bilirubine) should be performed within 4 to 8 weeks of starting therapy, and then monitored regularly during therapy with ARTHROTEC. Patient with symptoms and/or signs of liver dysfunction, or in whom an abnormal liver function test has occurred, their hepatic function (e.g. serum transaminases, bilirubine) should be monitored carefully for evidence of the development of a more severe hepatic reaction while on therapy with ARTHROTEC. If abnormal liver tests persist or worsen, ARTHROTEC should be discontinued.

Ophthalmologic: Patients on long-term treatment with ARTHROTEC should have an ophthalmologic examination performed periodically, and if they experience blurred and/or diminished vision.

Renal: Renal function should be monitored in high-risk populations, such as the elderly, patients with advanced renal disease, patients with cardiovascular disease and diabetes mellitus, as well as in the setting of concomitant use of diuretics and ACE inhibitors (see CONTRAINDICATIONS). If abnormal renal tests persist or worsen, ARTHROTEC should be discontinued.

Electrolytes, including serum potassium, should be monitored periodically, especially in patients with diabetes mellitus, renal failure, increased age, or those receiving concomitant therapy with adrenergic blockers, angiotensin-converting enzyme inhibitors, angiotensin-II receptor antagonists, cyclosporine, or some diuretics.

Laboratory abnormalities included increased alkaline phosphatase, decreased hematocrit and elevated SGPT (ALT).

Persistently abnormal or worsening renal, hepatic or hematological test values should be followed up carefully since they may be related to therapy.

Overview

Factors such as excess alcohol intake, smoking, and concomitant NSAID and oral steroid or anticoagulant use have been associated with increased risk of GI adverse events such as ulceration and bleeding. In laboratory studies, misoprostol has shown no significant effect on the cytochrome P450-linked hepatic mixed function oxidase system, and therefore should not affect the metabolism of theophylline, warfarin, benzodiazepines or other drugs normally metabolized by this system

Diclofenac metabolism is predominantly mediated via cytochrome P450 CYP 2C9 in the liver. Patients who are known or suspected to be poor CYP2C9 metabolizers based on previous history/experience with other CYP2C9 substrates should be administered diclofenac with caution as they may have abnormally high plasma levels due to reduced metabolic clearance. Caution is recommended when co-prescribing diclofenac with potent CYP2C9 inhibitors (such as sulfinpyrazone and voriconazole), which could result in a significant increase in peak plasma concentrations and exposure to diclofenac due to inhibition of diclofenac metabolism. Caution should be exercised when prescribing ARTHROTEC with concomitant drugs that are known to be potentially hepatotoxic (e.g. antibiotics, anti-epileptics).

Drug-Drug Interactions

Misoprostol has been used concomitantly with at least 44 different classes of drugs, including more than 150 drugs. There were no reports of any clinically significant drug interactions.

Acetylsalicylic Acid (ASA) or other NSAID's:
When diclofenac and ASA are taken simultaneously, the bioavailability of each is reduced. Concomitant administration of ARTHROTEC and ASA is not recommended because diclofenac is displaced from its binding sites by ASA, resulting in lower plasma concentrations, peak plasma levels and AUC values. Misoprostol does not affect the kinetics of other NSAIDs (e.g., ibuprofen, indomethacin and piroxicam). The use of ARTHROTEC in addition to any other NSAID, including those over the counter ones (such as ASA and ibuprofen) for analgesic and/or anti-inflammatory effects is NOT recommended because of the absence of any evidence demonstrating synergistic benefits and the potential for additive adverse reactions.

The exception is the use of low dose ASA for cardiovascular protection, when another NSAID is being used for its analgesic/anti-inflammatory effect, keeping in mind that combination NSAID therapy is associated with additive adverse reactions.

Some NSAIDs (e.g. ibuprofen) may interfere with the anti-platelet effects of low dose ASA, possibly by competing with ASA for access to the active site of cyclooxygenase-I.

Antacids:
Only aluminum-based antacids should be used with ARTHROTEC as magnesium-based antacids may increase the potential for diarrhea (see ADVERSE REACTIONS). The concomitant administration of aluminum hydroxide or magnesium hydroxide antacids may delay the absorption of diclofenac but does not affect the total amount of the drug absorbed. The total availability of misoprostol acid is reduced by antacids in large doses.

Anticoagulants:
Numerous studies have shown that the concomitant use of NSAIDs and anticoagulants increases the risk of GI adverse events such as ulceration and bleeding. Pharmacodynamic studies have shown no potentiation of anticoagulant drugs due to concurrent administration with diclofenac. However, other NSAIDs have been shown to interact with anticoagulant agents. Although clinical investigations would appear to indicate that diclofenac has no influence on the effect of anticoagulants, there are isolated reports of an increased risk of hemorrhage with the combined use of diclofenac and nicoumalone anticoagulant therapy. Special caution is therefore recommended and frequent laboratory tests should be performed to check that the desired response to the anticoagulant is being maintained. Because prostaglandins play an important role in hemostasis and NSAIDs affect platelet function as well, concurrent therapy of ARTHROTEC with warfarin requires close monitoring to be certain no change in anticoagulant dosage is necessary (see WARNINGS AND PRECAUTIONS – Hematologic – Anti-coagulants).

Anti-hypertensives:
NSAIDs may diminish the anti-hypertensive effect of diuretics and other antihypertensive drugs including Angiotensin Converting Enzyme (ACE) inhibitors, angiotensin II antagonists (AIIA) and beta-blockers.

Co-administration of ACE inhibitors, angiotensin-II antagonists, or diuretics with NSAIDs can have an increased risk for deterioration of renal function, acute renal failure and hyperkalemia. Blood pressure and renal function (including electrolytes) should be monitored more closely in this situation, as there can be a substantial increase in blood pressure.

Dehydrated patients or elderly patients with compromised renal function may be at greater risk.

Anti-platelet Agents (including ASA):
There is an increased risk of bleeding, via inhibition of platelet function, when anti-platelet agents are combined with NSAIDs, such as ARTHROTEC (see WARNINGS AND PRECAUTIONS – Hematologic – Anti-platelet Effects).

Cyclosporin or Tacrolimus:
When co-administered with cyclosporine, there is a two-fold increase in diclofenac systemic exposure. It is prudent to start with the lowest dose of diclofenac/misoprostol and to monitor closely for signs of toxicity.

Co-administration of cyclosporin or tacrolimus may also increase the nephrotoxic effect of cyclosporin or tacrolimus due to the NSAID's effect on renal prostaglandins. Renal function should be monitored when ARTHROTEC and either of these drugs is used in combination.

Digoxin:
Diclofenac may increase the plasma concentration of digoxin. Dosage adjustment of the digoxin may be required with ARTHROTEC. Serum digoxin levels should be monitored for possible digoxin toxicity.

Diuretics/Antihypertensives:
Clinical studies as well as post-marketing observations have shown that NSAIDs can reduce the effect of diuretics. Concomitant treatment of ARTHROTEC with potassium-sparing diuretics may be associated with increased serum potassium levels, thus making it necessary to monitor the latter. The antihypertensive effect of hydrochlorothiazide and ACE inhibitors may be decreased by diclofenac in patients with essential hypertension. Coadministration of ARTHROTEC with ACE inhibitors may result in an impairment of renal function.

Glucocorticoids:
Some studies have shown that the concomitant use of NSAIDs and oral glucocorticoids increases the risk of GI side effects such as ulceration and bleeding. This is especially the case in older (>65 years of age) individuals.

Lithium:
Diclofenac, when administered concomitantly with lithium, increases the lithium plasma concentration through an effect on lithium renal clearance. Lithium toxicity may develop in these patients. Dosage adjustment of lithium may be required with ARTHROTEC.

Methotrexate:
Concurrent administration of methotrexate and diclofenac may result in increased plasma levels of methotrexate and rare cases of fatal renal toxicity have been reported. Thus, caution should be taken when administering ARTHROTEC and methotrexate.

Oral Contraceptives:
No drug interaction data are available for ARTHTROTEC and the co-administration of oral contraceptives.

Oral hypoglycemic agents:
Diclofenac does not alter glucose metabolism in normal subjects, and pharmacodynamic studies have shown no potentiation of oral hypoglycemic drugs due to concurrent administration with diclofenac. However, other NSAIDs have been shown to interact with oral hypoglycemic agents. Therefore, ARTHROTEC should be administered with caution in patients receiving insulin or oral hypoglycemic agents.

Phenytoin:
When using phenytoin concomitantly with diclofenac, monitoring of phenytoin plasma concentrations is recommended due to an expected increase in exposure to phenytoin.

Selective Serotonin Reuptake Inhibitors (SSRIs):
Concomitant administration of NSAIDs and SSRIs may increase the risk of gastrointestinal ulceration and bleeding (see WARNINGS AND PRECAUTIONS – Gastrointestinal).

Sulfinpyrazone:
Concomitant administration of diclofenac and sulfinpyrazone could result in a significant increase in peak plasma concentrations and exposure to diclofenac due to inhibition of diclofenac metabolism.

Voriconazole:
Voriconazole increased C_max and AUC of diclofenac (50 mg single dose) by 114% and 78%, respectively.

Drug-Food Interactions

Interactions with food have not been established.

Drug-Herb Interactions

Interactions with herbal products have not been established.

Drug-Laboratory Interactions

Diclofenac increases platelet aggregation time but does not affect bleeding time, plasma prothrombin clotting time, plasma fibrinogens, or factors V and VII to XII. Statistically significant changes in prothrombin and partial thromboplastin times have been reported in normal volunteers. The mean changes were observed to be less than 1 second in both instances, and are unlikely to be clinically important.

Drug-Lifestyle Interactions

Smoking and alcohol intake should be discouraged while taking ARTHROTEC as they constitute risk factors for increased cardiovascular and gastrointestinal problems respectively. Patients experiencing visual disturbances, dizziness, vertigo, somnolence or other central nervous system disturbances while taking ARTHROTEC should refrain from driving or using machines.

Diclofenac Sodium

Worldwide reports on overdosage with diclofenac cover 27 cases. In 10 of these 27 cases, diclofenac was the only drug taken; all of these patients recovered. The highest dose of diclofenac was 2.5 g in a 20-year-old male who suffered acute renal failure as a consequence, and who was treated with dialysis sessions and recovered in 2 days. The next highest dose was 2.35 g in a 17-year-old female who experienced vomiting and drowsiness. A dose of 2.0 g of diclofenac was taken by a woman of unspecified age who remained asymptomatic.

There is no specific antidote for diclofenac. In cases of overdosage, absorption should be prevented as soon as possible by means of induction of vomiting, gastric lavage or treatment with activated charcoal.

Supportive and symptomatic treatment should be given for complications such as drowsiness, confusion, general hypotonia, hypotension, renal failure, convulsions, gastrointestinal irritation and respiratory depression. Measures to accelerate elimination (forced diuresis, hemoperfusion, dialysis) may be considered, but may be of limited use because of the high protein-binding and extensive metabolism (diclofenac 99% protein bound and misoprostol acid less than 90% protein bound).

Misoprostol

The toxic dose of misoprostol in humans has not been determined. Cumulative total daily doses of 1,600 µg have been tolerated with only symptoms of gastrointestinal discomfort being reported.

Clinical signs that may indicate an overdose are sedation, tremor, convulsions, dyspnea, abdominal pain, diarrhea, fever, palpitations, hypotension, or bradycardia. Symptoms should be treated with supportive therapy.

It is not known if misoprostol acid is dialyzable. However, because misoprostol is metabolized like a fatty acid, it is unlikely that dialysis would be appropriate treatment for overdosage.

The use of oral activated charcoal may help to reduce the absorption of diclofenac and misoprostol.

Store at 15 to 25°C and protect from heat and humidity.