Pharmacodynamics

Etodolac extended-release tablets are a nonsteroidal anti-inflammatory drug (NSAID) that exhibits anti-inflammatory, analgesic, and antipyretic activities in animal models. The mechanism of action of etodolac extended-release tablets, like that of other NSAIDs, is not completely understood, but may be related to prostaglandin synthetase inhibition.

Pharmacokinetics

Arthritis

The use of etodolac extended-release tablets in managing the signs and symptoms of osteoarthritis of the knee and rheumatoid arthritis was assessed in double-blind, randomized, parallel, controlled clinical trials in 1552 patients. In these trials, etodolac extended-release tablets, given once daily, provided efficacy comparable to immediate-release etodolac.

The safety, efficacy, and pharmacokinetics of etodolac extended-release tablets were assessed in an open-label, 12-week clinical trial. Seventy-two (72) patients, 6 to 16 years of age, with juvenile rheumatoid arthritis, received etodolac extended-release tablets in doses of 400 to 1000 mg (13.3 to 21.3 mg/kg body weight) once daily. At these doses, etodolac extended-release tablets controlled the signs and symptoms of juvenile rheumatoid arthritis. Based on the results of this study, the safety profile of etodolac extended-release tablets (at doses not exceeding 20 mg/kg) appeared to be similar to that observed in the adult arthritic patients in clinical trials. (See PRECAUTIONS, Pediatric Use).

Cardiovascular Effects

Gastrointestinal Effects - Risk of Ulceration, Bleeding, and Perforation

NSAIDs, including etodolac extended-release tablets, 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 to 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.

Renal Effects

Long-term administration of NSAIDs has resulted in renal papillary necrosis and other renal injury. Renal toxicity has also been seen in patients in whom renal prostaglandins have a compensatory role in the maintenance of renal perfusion. In these patients, administration of a nonsteroidal anti-inflammatory drug may cause a dose-dependent reduction in prostaglandin formation and, secondarily, in renal blood flow, which may precipitate overt renal decompensation. Patients at greatest risk of this reaction are those with impaired renal function, heart failure, liver dysfunction, those taking diuretics and ACE inhibitors, and the elderly. Discontinuation of NSAID therapy is usually followed by recovery to the pretreatment state.

Renal pelvic transitional epithelial hyperplasia, a spontaneous change occurring with variable frequency, was observed with increased frequency in treated male rats in a 2-year chronic study. Caution is recommended in patients with pre-existing kidney disease.

Advanced Renal Disease

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

Anaphylactoid Reactions

As with other NSAIDs, anaphylactoid reactions may occur in patients without known prior exposure to etodolac extended-release tablets. Etodolac extended-release tablets should not be given to patients with the aspirin 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 aspirin or other NSAIDs (see CONTRAINDICATIONS and PRECAUTIONS, Preexisting Asthma). Emergency help should be sought in cases where an anaphylactoid reaction occurs.

Skin Reactions

NSAIDs, including etodolac extended-release tablets, can cause serious skin adverse events such as exfoliative dermatitis, Stevens-Johnson Syndrome (SJS), and toxic epidermal necrolysis (TEN), which can be fatal. These serious events may occur without warning. Patients should be informed about the signs and symptoms of serious skin manifestations and use of the drug should be discontinued at the first appearance of skin rash or any other sign of hypersensitivity.

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) has been reported in patients taking NSAIDs such as etodolac extended-release tablets. Some of these events have been fatal or life-threatening. DRESS typically, although not exclusively, presents with fever, rash, lymphadenopathy, and/or facial swelling. Other clinical manifestations may include hepatitis, nephritis, hematological abnormalities, myocarditis, or myositis. Sometimes symptoms of DRESS may resemble an acute viral infection. Eosinophilia is often present. Because this disorder is variable in its presentation, other organ systems not noted here may be involved. It is important to note that early manifestations of hypersensitivity, such as fever or lymphadenopathy, may be present even though rash is not evident. If such signs or symptoms are present, discontinue etodolac extended-release tablets and evaluate the patient immediately.

Fetal Toxicity

General

Etodolac extended-release tablets cannot be expected to substitute for corticosteroids or to treat corticosteroid insufficiency. Abrupt discontinuation of corticosteroids may lead to disease exacerbation. Patients on prolonged corticosteroid therapy should have their therapy tapered slowly if a decision is made to discontinue corticosteroids.

The pharmacological activity of etodolac extended-release tablets in reducing fever and inflammation may diminish the utility of these diagnostic signs in detecting complications of presumed noninfectious, painful conditions.

Hepatic Effects

Borderline elevations of one or more liver tests may occur in up to 15% of patients taking NSAIDs including etodolac extended-release tablets. 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 etodolac extended-release tablets. If clinical signs and symptoms consistent with liver disease develop, or if systemic manifestations occur (e.g., eosinophilia, rash, etc.), etodolac extended-release tablets should be discontinued.

Hematological Effects

Anemia is sometimes seen in patients receiving NSAIDs, including etodolac extended-release tablets. 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 etodolac extended-release tablets, 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 etodolac extended-release tablets 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, etodolac extended-release tablets should not be administered to patients with this form of aspirin sensitivity and should be used with caution in patients with preexisting asthma.

Information for Patients

Patients should be informed of the following information before initiating therapy with an NSAID and periodically during the course of ongoing therapy. Patients should also be encouraged to read the NSAID Medication Guide that accompanies each prescription dispensed.

1. Cardiovascular Thrombotic Events
   
   Advise patients to be alert for the symptoms of cardiovascular thrombotic events, including chest pain, shortness of breath, weakness, or slurring of speech, and to report any of these symptoms to their health care provider immediately (see WARNINGS).
2. Etodolac extended-release tablets, like other NSAIDs, can cause GI discomfort and, rarely, serious GI side effects, such as ulcers and bleeding, which may result in hospitalization and even death. Although serious GI tract ulcerations and bleeding can occur without warning symptoms, patients should be alert for the signs and symptoms of ulcerations and bleeding, and should ask for medical advice when observing any indicative sign or symptoms including epigastric pain, dyspepsia, melena, and hematemesis. Patients should be apprised of the importance of this follow-up (see WARNINGS, Gastrointestinal Effects - Risk of Ulceration, Bleeding, and Perforation).
3. Serious Skin Reactions, including DRESS
   
   Advise patients to stop taking etodolac extended-release tablets immediately if they develop any type of rash or fever and to contact their healthcare provider as soon as possible [see Warnings].
4. Heart Failure and Edema
   
   Advise patients to be alert for the symptoms of congestive heart failure including shortness of breath, unexplained weight gain, or edema and to contact their healthcare provider if such symptoms occur (see WARNINGS).
5. Patients should be informed of the warning signs and symptoms of hepatotoxicity (e.g., nausea, fatigue, lethargy, pruritus, jaundice, right upper quadrant tenderness, and "flu-like" symptoms). If these occur, patients should be instructed to stop therapy and seek immediate medical therapy.
6. Patients should be informed of the signs of an anaphylactoid reaction (e.g., difficulty breathing, swelling of the face or throat). If these occur, patients should be instructed to seek immediate emergency help (see WARNINGS).
7. Fetal Toxicity
   
   Inform pregnant women to avoid use of etodolac extended-release tablets and other NSAIDs starting at 30 weeks gestation because of the risk of the premature closing of the fetal ductus arteriosus. If treatment with etodolac extended-release tablets is needed for a pregnant woman between about 20 to 30 weeks gestation, advise her that she may need to be monitored for oligohydramnios, if treatment continues for longer than 48 hours [see WARNINGS; Fetal Toxicity, PRECAUTIONS; Pregnancy].

Laboratory Tests

Because serious GI tract ulcerations and bleeding can occur without warning symptoms, physicians should monitor for signs or symptoms of GI bleeding. Patients on long-term treatment with NSAIDs, should have their CBC and a chemistry profile checked periodically. If clinical signs and symptoms consistent with liver or renal disease develop, systemic manifestations occur (e.g., eosinophilia, rash, etc.) or if abnormal liver tests persist or worsen, etodolac extended-release tablets should be discontinued.

Drug Interactions

Drug/Laboratory Test Interactions

The urine of patients who take etodolac can give a false-positive reaction for urinary bilirubin (urobilin) due to the presence of phenolic metabolites of etodolac. Diagnostic dip-stick methodology, used to detect ketone bodies in urine, has resulted in false-positive findings in some patients treated with etodolac. Generally, this phenomenon has not been associated with other clinically significant events. No dose relationship has been observed.

Etodolac treatment is associated with a small decrease in serum uric acid levels. In clinical trials, mean decreases of 1 to 2 mg/dL were observed in arthritic patients receiving etodolac (600 mg to 1000 mg/day) after 4 weeks of therapy. These levels then remained stable for up to 1 year of therapy.

Carcinogenesis, Mutagenesis, and Impairment of Fertility

No carcinogenic effect of etodolac was observed in mice or rats receiving oral doses of 15 mg/kg/day (45 to 89 mg/m2, respectively) or less for periods of 18 months or 2 years, respectively. Etodolac was not mutagenic in in vitro tests performed with S. typhimurium and mouse lymphoma cells as well as in an in vivo mouse micronucleus test. However, data from the in vitro human peripheral lymphocyte test showed an increase in the number of gaps (3% to 5% unstained regions in the chromatid without dislocation) among the etodolac-treated cultures (50 to 200 g/mL) compared to negative controls (2%); no other difference was noted between the controls and drug-treated groups. Etodolac showed no impairment of fertility in male and female rats up to oral doses of 16 mg/kg (94 mg/m2). However, reduced implantation of fertilized eggs occurred in the 8 mg/kg group.

Pregnancy

Labor and Delivery

In rat studies with NSAIDs, as with other drugs known to inhibit prostaglandin synthesis, an increased incidence of dystocia, delayed parturition, and decreased pup survival occurred. The effects of etodolac extended-release tablets on labor and delivery in pregnant women are unknown.

Nursing Mothers

It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from etodolac extended-release tablets, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

Pediatric Use

Safety and effectiveness in pediatric patients below the age of 6 years have not been established.

Geriatric Use

As with any NSAIDs, caution should be exercised in treating the elderly (65 years and older).

Additional NSAID Adverse Experiences Reported Occasionally with NSAIDs or Etodolac Extended-Release Tablets Include

Body as a whole - allergic reaction, anaphylactic/anaphylactoid reactions (including shock), chills, fever, sepsis

Cardiovascular system - congestive heart failure, flushing, palpitations, tachycardia, syncope, vasculitis (including necrotizing and allergic)

Digestive system - anorexia, cholestatic hepatitis, cholestatic jaundice, dry mouth, duodenitis, eructation, esophagitis, gastritis, gastric/peptic ulcers, glossitis, hepatic failure, hepatitis, hematemesis, intestinal ulceration, jaundice, liver necrosis, melena, pancreatitis, rectal bleeding, stomatitis

Hemic and lymphatic system - agranulocytosis, ecchymosis, eosinophilia, hemolytic anemia, leukopenia, neutropenia, pancytopenia, purpura, thrombocytopenia

Metabolic and nutritional - hyperglycemia in previously controlled diabetic patients

Nervous system - anxiety, confusion, depression, dream abnormalities, insomnia, nervousness, paresthesia, somnolence, tremors, vertigo

Respiratory system - asthma, dyspnea, pulmonary infiltration with eosinophilia

Skin and appendages - angioedema, cutaneous vasculitis with purpura, erythema multiforme, hyperpigmentation, sweating, urticaria, vesiculobullous rash

Special senses - blurred vision, photophobia, transient visual disturbances

Urogenital system - dysuria, elevated BUN, oliguria/polyuria, proteinuria, renal failure, renal insufficiency, renal papillary necrosis, serum creatinine increase, urinary frequency

Other NSAID Adverse Reactions, Which Occur Rarely Are

Body as a whole - anaphylactic reactions, appetite changes, death

Cardiovascular system - arrhythmia, cerebrovascular accident, hypotension, myocardial infarction

Digestive system - colitis, esophagitis with or without stricture or cardiospasm, thirst, ulcerative stomatitis

Hemic and lymphatic system - aplastic anemia, lymphadenopathy

Metabolic and nutritional - change in weight

Nervous system - coma, convulsions, hallucinations, meningitis

Respiratory - bronchitis, pneumonia, respiratory depression, sinusitis

Skin and appendages - alopecia, exfoliative dermatitis, maculopapular rash, photosensitivity, skin peeling, Stevens-Johnson syndrome, toxic epidermal necrosis

Special senses - conjunctivitis, deafness, hearing impairment, taste perversion

Urogenital system - cystitis, hematuria, interstitial nephritis, leukorrhea, renal calculus, uterine bleeding irregularities

Juvenile Rheumatoid Arthritis

For the relief of the signs and symptoms of juvenile rheumatoid arthritis in patients 6 to 16 years of age, the recommended dose given orally once per day should be based on body weight, according to the following table:

Rheumatoid Arthritis and Osteoarthritis

For the relief of the signs and symptoms of osteoarthritis or rheumatoid arthritis, the recommended starting dose of etodolac extended-release tablets is 400 to 1000 mg given orally once per day.

As with other NSAIDs, the lowest effective dose should be sought for each patient. In chronic conditions, a therapeutic response to therapy with etodolac extended-release tablets is sometimes seen within one week of therapy, but most often is observed by two weeks.

Store at 20° to 25°C (68° to 77°F) [see USP Controlled Room Temperature].

Protect from excessive heat and humidity.

Dispense in a tight, light-resistant container as defined in the USP, with a child-resistant closure (as required).