Diclofenac Sodium – Misoprostol
Anti-inflammatory – Analgesic – Mucosal Protective Agent
Action And Clinical Pharmacology: Arthrotec is a combination of a nonsteroidal anti-inflammatory drug (NSAID) with analgesic properties and a mucosal protective synthetic analog of prostaglandin E1.
Arthrotec has been shown to be as effective as diclofenac in reducing the signs and symptoms of rheumatoid arthritis and osteoarthritis. In addition, Arthrotec has been associated with a lower incidence of gastroduodenal erosions and ulcers than diclofenac.
Diclofenac inhibits prostaglandin synthesis by interfering with the action of prostaglandin synthetase. This inhibitory effect may partially explain its actions, both therapeutic and adverse. From a clinical efficacy standpoint, diclofenac (150 mg daily) is similar in activity to equivalent dosages of 3.6 to 4.8 g daily of ASA. Diclofenac is similar in activity to equivalent dosages of indomethacin (75 to 150 mg daily). Although diclofenac does not alter the course of the underlying disease, it has been found to relieve pain, reduce fever, swelling and tenderness, and increase mobility in patients with rheumatic disorders of the types listed under Indications.
Studies in healthy subjects indicate that misoprostol enhances several of the factors implicated in maintaining gastroduodenal mucosal integrity. Misoprostol has been shown to inhibit both basal and stimulated gastric acid secretion. In addition, increases in gastric mucosal blood flow, duodenal bicarbonate secretion and gastric mucus secretion have all been observed following treatment with misoprostol. The ability of misoprostol to protect the gastric and duodenal mucosa has been confirmed in studies in both healthy subjects and patients with rheumatoid arthritis or osteoarthritis. Endoscopic examination and measurement of fecal blood loss have shown that coadministration of misoprostol prevents mucosal injury induced by a variety of NSAIDs, including, ASA, ibuprofen, piroxicam, naproxen, tolmetin and diclofenac.
Pharmacokinetics: Following administration of a single dose of Arthrotec 50 to 36 healthy male subjects, the mean Cmax, AUC (0 to 24) and Tmax for diclofenac were 1.13 g/mL, 1.63 g.h/mL and 3.9 h, respectively, while the mean Cmax, AUC (0 to 4) and Tmax for the principal active metabolite of misoprostol (misoprostol acid) were 136 pg/mL, 238 pg.h/mL and 0.87 h, respectively.
Following a single dose of Arthrotec 75 to 35 healthy male and female subjects, the mean Cmax, AUC (0 to 12) and Tmax for diclofenac were 2.03 g/mL, 2.77 g.h/mL and 1.96 h, respectively. The mean Cmax, AUC (0 to 4) and Tmax for the principal metabolite of misoprostol (misoprostol acid) were 304 pg/mL, 177 pg.h/mL and 0.26 h, respectively.
Orally administered diclofenac is rapidly and almost completely absorbed. Forty to 60% of the drug and its metabolites are eliminated in the urine and the balance in the bile.
Orally administered misoprostol is also rapidly and extensively absorbed, and undergoes rapid metabolism to misoprostol acid, which is thereafter quickly eliminated (elimination half-life of approximately 30 minutes). Approximately 70% of the dose is excreted in the urine, mainly as biologically inactive metabolites.
Influence of Food: With Arthrotec the effect of food on the bioavailability of the diclofenac and misoprostol components is similar to that reported for the individual drugs. The times of peak concentration (Tmax) for diclofenac and misoprostol are prolonged by approximately 50 and 100% respectively, while the peak concentrations (Cmax) are decreased by about 25% for diclofenac and 50% for misoprostol: the AUC for diclofenac is decreased by approximately 60%, while that of misoprostol is increased by about 25%.
Clinical Use: In 2 multicentre, double-blind, controlled clinical trials of 12 weeks duration involving a total of 346 and 339 patients respectively, patient global assessments of the arthritic condition revealed no statistically significant differences between Arthrotec 50 and a fixed-combination of diclofenac/placebo.
In 2 multicentre, double-blind, controlled trials of 4 weeks duration in 455 and 361 patients with osteoarthritis, patient global assessments of the arthritic condition revealed no overall differences between Arthrotec 50 and diclofenac/placebo.
A multicentre, double-blind, controlled trial of 6 weeks duration involving a total of 572 patients (154 in the diclofenac group, 152 in the Arthrotec 50 group, 175 in the Arthrotec 75 group and 91 in the placebo group) showed that Arthrotec 50 three times daily and Arthrotec 75 twice daily were equivalent to diclofenac/placebo in relieving the signs and symptoms of osteoarthritis.
A multicentre, double-blind, controlled trial of 12 weeks duration involving a total of 380 patients (107 in the diclofenac group, 107 in the Arthrotec 50 group, 111 in the Arthrotec 75 group and 55 in the placebo group) showed that Arthrotec 50 three times daily and Arthrotec 75 twice daily were equivalent to diclofenac/placebo in relieving the signs and symptoms of rheumatoid arthritis.
Misoprostol has been compared to placebo in the prevention of clinically significant and serious gastrointestinal events associated with NSAID use. In a 6-month, double-blind study of 8 843 patients (4 404 in the misoprostol group, 4 439 in the placebo group, mean age 68 years) with rheumatoid arthritis, misoprostol significantly reduced the incidence of serious complications, such as gastrointestinal bleeding and ulcer perforation, by 40 to 50%.
Arthrotec is associated with a low incidence of gastroduodenal lesions relative to diclofenac/placebo.
Indications And Clinical Uses: For acute and chronic use in the relief of the signs and symptoms of rheumatoid arthritis and osteoarthritis.
Contra-Indications: The contraindications of Arthrotec are those of the components of the product.
Diclofenac is contraindicated in the following conditions: active peptic ulcer, a history of recurrent ulceration or active inflammatory disease of the gastrointestinal system.
Known or suspected hypersensitivity to the drug or other nonsteroidal anti-inflammatory drugs (NSAIDs). The potential for cross-reactivity between different NSAIDs must be kept in mind. Diclofenac should not be used in patients in whom asthma, anaphylaxis, urticaria, rhinitis or other allergic manifestations are precipitated by ASA or other nonsteroidal anti-inflammatory agents. 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 effects.
Significant hepatic impairment or active liver disease.
Diclofenac is not recommended for use with other NSAIDs because of the absence of any evidence demonstrating synergistic benefits and the potential for additive side effects.
Pregnancy: Arthrotec is contraindicated in pregnancy. Women should be advised not to become pregnant while taking Arthrotec. If pregnancy is suspected, use of the product should be discontinued, and the pregnancy followed closely.
Manufacturers’ Warnings In Clinical States: Gastrointestinal: The presence of misoprostol in the product may protect against the mucosal damaging effects of the other component, diclofenac.
However, serious gastrointestinal toxicity, such as peptic ulceration, perforation and gastrointestinal bleeding, sometimes severe and occasionally fatal can occur at any time, with or without symptoms in patients treated with NSAIDs including diclofenac.
Minor upper gastrointestinal problems, such as dyspepsia, are common, usually developing early in therapy. Physicians should remain alert for ulceration and bleeding in patients treated with NSAIDs, even in the absence of previous gastrointestinal tract symptoms.
In clinical trials, 3 549 arthritic patients have been treated with Arthrotec, 506 of whom received Arthrotec for more than 1 year. A total of 285 patients have been treated with Arthrotec 75 in clinical trials for a duration of up to 12 weeks.
Diclofenac should be given under close medical supervision to patients prone to gastrointestinal tract irritation, particularly those with a history of peptic ulcer; diverticulosis or other inflammatory disease of the gastrointestinal tract such as ulcerative colitis and Crohn’s disease. In these cases the physician must weigh the benefits of treatment against the possible hazards.
Physicians should inform patients about the signs and/or symptoms of serious gastrointestinal toxicity and instruct them to contact a physician immediately if they experience persistent dyspepsia or other symptoms or signs suggestive of gastrointestinal ulceration or bleeding.
Because serious gastrointestinal 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 and should inform the patients of the importance of this followup.
If ulceration is suspected or confirmed, or if gastrointestinal 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. A prior history of serious gastrointestinal events and other factors such as excess alcohol intake, smoking, age, female gender and concomitant oral steroid and anticoagulant use have been associated with increased risk.
Studies to date show that all NSAIDs can cause gastrointestinal tract adverse events. Although existing data does not clearly identify differences in risk between various NSAIDs, this may be shown in the future.
Geriatrics: Patients older than 65 years and frail or debilitated patients are most susceptible to a variety of adverse reactions from NSAIDs, their incidence increases with dose and duration of treatment. In addition, these patients are less tolerant of ulceration and bleeding, and most reports of fatal gastrointestinal events are in this population. Older patients are also at risk of lower esophageal ulceration and bleeding.
For such patients, consideration should be given to a starting dose lower than usual, with individual adjustment when necessary and under close supervision.
Cross Sensitivity: Patients sensitive to one of the nonsteroidal anti-inflammatory drugs may be sensitive to any of the other NSAIDs also.
Aseptic Meningitis: In occasional cases, 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 tissues diseases, etc.) seem to be predisposed. Therefore, in such patients, the physician must weigh the benefits of therapy against the possible hazards before prescribing and must be vigilant to the development of this complication.
Lactation: It is not recommended that Arthrotec be administered to nursing mothers. Diclofenac has been found in human milk. It is unlikely that misoprostol is secreted in human milk since it is rapidly metabolized throughout the body. It is not known if the active metabolite of misoprostol (misoprostol acid) is secreted in human milk. However, the potential presence of misoprostol acid in human milk could cause diarrhea in nursing infants.
Women of Childbearing Potential: Arthrotec should not be used in women of childbearing potential unless they use effective contraception (i.e., oral contraceptives or intrauterine devices) and have been advised of the risks of taking Arthrotec if pregnant.
Children: The safety and effectiveness of Arthrotec in children below the age of 18 years have not been established.
Precautions: Renal Function: As with other NSAIDs, long-term administration of diclofenac to animals has resulted in renal papillary necrosis and other abnormal renal pathology. In humans, there have been reports of acute interstitial nephritis with hematuria, proteinuria, and occasionally nephrotic syndrome.
A second form of renal toxicity has been seen in patients with prerenal conditions leading to the reduction in renal blood flow or blood volume, where the renal prostaglandins have a supportive role in the maintenance of renal perfusion. In these patients, administration of an NSAID may cause a dose dependent reduction in prostaglandin formation and 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 the elderly. Discontinuation of nonsteroidal anti-inflammatory therapy is usually followed by recovery to the pretreatment state.
Diclofenac and its metabolites are eliminated primarily by the kidneys, therefore the drug should be used with great caution in patients with impaired renal function. In these cases, lower dose of diclofenac should be anticipated and patients carefully monitored.
During long-term therapy kidney function should be monitored periodically.
Genitourinary Tract: Some NSAIDs are known to cause 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, treatment with Arthrotec must be stopped immediately to obtain recovery. This should be done before any urological investigations or treatments are carried out.
Hepatic Function: As with other NSAIDs, borderline elevations of one or more liver function tests may occur in up to 15% of patients. These abnormalities may progress, may remain essentially unchanged, or may be transient with continued therapy. 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. Severe hepatic reactions including jaundice and cases of fatal hepatitis have been reported with this drug as with other NSAIDs.
Although such reactions are rare, if abnormal liver tests persist or worsen, if clinical signs and symptoms consistent with liver disease develop, or if systemic manifestations occur (e.g., eosinophilia, rash, etc.), this drug should be discontinued.
During long-term therapy, liver function tests should be monitored periodically. If this drug needs to be used in the presence of impaired liver function, it must be done under strict observation.
Fluid and Electrolyte Balance: Fluid retention and edema have been observed in patients treated with Arthrotec. Therefore, as with many other NSAIDs, the possibility of precipitating congestive heart failure in elderly patients or those with compromised cardiac function should be borne in mind.
Arthrotec should be used with caution in patients with heart failure, hypertension or other conditions predisposing to fluid retention. With NSAID 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.
Hematology: Drugs inhibiting prostaglandin biosynthesis do interfere with platelet function to varying degrees. Therefore, patients who may be adversely affected by such an action should be carefully observed when Arthrotec is administered.
The addition of misoprostol does not exacerbate the effect of diclofenac on platelet function. In clinical trials, there has been no evidence that Arthrotec affects hemostasis.
Blood dyscrasias (such as neutropenia, leukopenia, thrombocytopenia, aplastic anemia and agranulocytosis) associated with the use of NSAIDs are rare, but could occur with severe consequences.
Infection: In common with other anti-inflammatory drugs, Arthrotec may mask the usual signs of infection.
Ophthalmology: Blurred and/or diminished vision has been reported with the use of NSAIDs. If such symptoms develop Arthrotec should be discontinued and an ophthalmologic examination performed; ophthalmic examination should be carried out at periodic intervals in any patient receiving this drug for an extended period of time.
CNS: Some patients may experience drowsiness, dizziness, vertigo, insomnia or depression with the use of diclofenac. If patients experience these side effects, they should exercise caution in carrying out activities that require alertness.
Allergies: Allergic reactions have been reported in individuals without prior exposure to diclofenac.
Drug Interactions: No drug-drug interactions for Arthrotec have been observed. However, the following information is known for the components.
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.
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.
ASA or Other NSAIDs: 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 and any other NSAIDs, including over the counter ones (such as ASA and ibuprofen) is not recommended due to the possibility of additive side effects.
Antacids: 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. Only aluminum-based antacids should be used with Arthrotec as magnesium-based antacids may increase the potential for diarrhea (see Adverse Effects).
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.
Diuretics/Antihypertensives: NSAIDs have been reported to inhibit the activity 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 other agents may be decreased by diclofenac in patients with essential hypertension.
Anticoagulants: Numerous studies have shown that concomitant use of NSAIDs and anticoagulants increases the risk of gastrointestinal 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.
Oral Hypoglycemic Agents: 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.
Methotrexate: Rare cases of fatal renal toxicity have been reported in patients receiving methotrexate and diclofenac. Thus, caution should be taken when administering Arthrotec and methotrexate.
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.
Glucocorticoids: Numerous studies have shown that the concomitant use of NSAIDs and oral glucocorticoids increases the risk of gastrointestinal side effects such as ulceration and bleeding. This is especially the case in older (>65 years old) individuals.
Clinical Laboratory Tests: 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.
Persistently abnormal or worsening renal, hepatic or hematological test values should be followed up carefully since they may be related to therapy.
Adverse Reactions: The most common adverse reactions encountered with NSAIDs are gastrointestinal, of which peptic ulcer, with or without bleeding, is the most severe. Fatalities have occurred, particularly in the elderly.
In clinical trials, 3 549 arthritic patients have been treated with Arthrotec, 506 of whom received Arthrotec for more than 1 year. A total of 285 patients have been treated with Arthrotec 75 in clinical trials for a duration of up to 12 weeks.
The following adverse reactions occurred with an incidence of 1% or greater with at least one of the Arthrotec dosing regimens presented below: See Table II.
The following adverse events were reported by 1% or less of the subjects receiving Arthrotec. Causal relationships between Arthrotec and these events have not been established but cannot be excluded.
Gastrointestinal: abdomen enlarged, esophageal ulceration, gall bladder disorder, glossitis, hematemesis, hiccup and melena.
CNS/Psychiatric: anorexia, anxiety, concentration impaired, depression, hypoesthesia, mouth dry, speech disorder and vertigo.
Dermatologic: angioedema, erythematous rash, sweating increased and urticaria.
Cardiovascular: palpitation and syncope.
Special Senses: earache, eye pain, taste loss, taste abnormalities, tinnitus and vision abnormal.
Hematologic: leukopenia and thrombocytopenia.
Hepatic: bilirubinemia, abnormal hepatic function, LDH increased, and alkaline phosphatase increased.
Metabolic: BUN increased and glycosuria.
Respiratory: hyperventilation and sputum increased.
Gynecological: menstrual disorder, intermenstrual bleeding, dysmenorrhea, leukorrhea, and vaginal bleeding. (Postmenopausal vaginal bleeding may be related to Arthrotec administration. If this occurs, diagnostic workup should be undertaken to rule out gynecological pathology.)
Body as a Whole: hot flushes, malaise, rigors.
Urinary: dysuria and urine abnormal.
Symptoms And Treatment Of Overdose: Symptoms and Treatment: 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 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 (99%) protein-binding and extensive metabolism.
Misoprostol: The toxic dose of misoprostol in humans has not been determined. Cumulative total daily doses of 1 600 g have been tolerated with only symptoms of gastrointestinal discomfort being reported.
In animals, the acute toxic effects are similar to those reported for other prostaglandins: relaxation of smooth muscle, respiratory difficulties, and depression of the CNS. 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.
Dosage And Administration: Adults: The recommended oral dose for treating the signs and symptoms of rheumatoid arthritis and osteoarthritis is Arthrotec 50: 1 tablet 2 or 3 times daily; Arthrotec 75: 1 tablet twice daily.
Arthrotec should be taken immediately after a meal or with food or milk.
Arthrotec should be swallowed whole.
No adjustment of dosage is necessary in patients with hepatic impairment or in mild to moderate renal failure as the pharmacokinetic parameters for Arthrotec are not altered to any clinically relevant extent. If Arthrotec must be used in patients with severe renal or hepatic impairment, these patients must be closely monitored.
Geriatrics: The dosage should be reduced to the lowest dose that will provide control of symptoms, adjusted when necessary, and closely supervised.
Availability And Storage: Arthrotec 50: Each white to off-white, round and biconvex tablet, engraved “SEARLE” over “1411” on one side, 4´ “A” around the circumference of the reverse side, contains: an enteric-coated core of diclofenac sodium 50 mg, surrounded by an outer mantle containing misoprostol 200 g. Nonmedicinal ingredients: castor oil, cellulose, cellulose acetate phthalate, colloidal silicon dioxide, cornstarch, crospovidone, diethyl phthalate, hydroxypropyl methylcellulose, lactose, magnesium stearate and povidone. Bottles of 250.
Arthrotec 75: Each white to off-white, round and biconvex tablet, engraved “SEARLE” over “1421” on one side, 4´ “A” around the circumference of the reverse side with a “75” in the middle, contains: an enteric-coated core of diclofenac sodium 75 mg, surrounded by an outer mantle containing misoprostol 200 g. Nonmedicinal ingredients: castor oil, cellulose, colloidal silicon dioxide, cornstarch, crospovidone, hydroxypropyl methylcellulose, lactose, magnesium stearate, methacrylic acid copolymer, povidone, sodium hydroxide and triethyl citrate. Bottles of 250.
Protect tablets from heat and humidity. Store at 15 to 25°C. Pharmacist: Dispense with patient insert. (Shown in Product Recognition Section)
ARTHROTEC® Searle Diclofenac Sodium – Misoprostol Anti-inflammatory – Analgesic – Mucosal Protective Agent