Acetaminophen and Ibuprofen

COMBOGESIC is indicated in adults for the short-term management of mild to moderate acute pain. COMBOGESIC is a combination of acetaminophen and ibuprofen, a non-steroidal anti-inflammatory drug (NSAID), and is indicated in adults for the short term management of mild to moderate acute pain ( 1 ).

Tablets: white, biconvex, capsule-shaped, film-coated tablets, debossed with the letters "CG" on one side and plain on the other side, each containing 325 mg acetaminophen and 97.5 mg ibuprofen. Film-coated tablet containing 325 mg acetaminophen and 97.5 mg ibuprofen ( 3 ).

COMBOGESIC is contraindicated in: patients with a known hypersensitivity (e.g., anaphylactic reactions, serious skin reactions) to acetaminophen, ibuprofen, other NSAIDs, or to any of the excipients in this product [see Warnings and Precautions (5.7 , 5.8 , 5.9) ]. patients with a history of asthma, urticaria, or other allergic-type reactions after taking aspirin or other NSAIDS [see Warnings and Precautions (5.7 and 5.8) ] . the setting of coronary artery bypass graft (CABG) surgery [see Warnings and Precautions (5.2) ] . COMBOGESIC is contraindicated in: patients with known hypersensitivity to acetaminophen, ibuprofen, other NSAIDs, or to any of the excipients in this product ( 4 ). patients with a history of asthma, urticaria, or other allergic-type reactions after taking aspirin or other NSAIDs. Severe, sometimes fatal, anaphylactic reactions to NSAIDs have been reported in such patients ( 4 ). the setting of coronary artery bypass graft (CABG) surgery ( 4 ).

Hypertension : Patients taking some antihypertensive medications may have impaired response to these therapies when taking NSAIDs. Monitor blood pressure ( 5.4 ). Heart Failure and Edema : Avoid use of COMBOGESIC in patients with severe heart failure unless benefits are expected to outweigh risk of worsening heart failure ( 5.5 ). Renal Toxicity : Long-term administration of NSAIDs, including the ibuprofen component of COMBOGESIC, has resulted in renal papillary necrosis and other renal injury ( 5.6 ). Anaphylactic Reactions : Seek emergency help if an anaphylactic reaction occurs ( 5.7 ). Exacerbation of Asthma Related to Aspirin Sensitivity : COMBOGESIC is contraindicated in patients with aspirin-sensitive asthma. Monitor patients with preexisting asthma (without aspirin sensitivity) ( 5.8 ). Serious Skin Reactions : Discontinue COMBOGESIC at first appearance of skin rash or other signs of hypersensitivity ( 5.9 ). Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) : Discontinue and evaluate clinically ( 5.10 ). Fetal Toxicity : Limit use of NSAID-containing products, including COMBOGESIC, between about 20 to 30 weeks in pregnancy due to the risk of oligohydramnios/fetal renal dysfunction. Avoid use of NSAID-containing products, including COMBOGESIC in women at about 30 weeks gestation and later in pregnancy due to the risks of oligohydramnios/fetal renal dysfunction and premature closure of the fetal ductus arteriosus ( 5.11 ). Hematologic Toxicity : Monitor hemoglobin or hematocrit in patients with any signs or symptoms of anemia ( 5.12 ).

5.1 Hepatotoxicity Acetaminophen COMBOGESIC contains acetaminophen. Acetaminophen has been associated with cases of acute liver failure, at times resulting in liver transplant and death. Most of the cases of liver injury are associated with the use of acetaminophen at doses that exceed 4,000 milligrams per day, and often involved more than one acetaminophen-containing product. The excessive intake of acetaminophen may be intentional to cause self-harm or unintentional as patients attempt to obtain more pain relief or unknowingly take other acetaminophen-containing products. The risk of acute liver failure is higher in individuals with underlying liver disease and in individuals who ingest alcohol while taking acetaminophen. Instruct patients to look for acetaminophen or APAP on package labels and not to use more than one product that contains acetaminophen. Instruct patients to seek medical attention immediately upon ingestion of more than 4,000 milligrams of acetaminophen per day, even if they feel well. Ibuprofen Elevations of ALT or AST (three or more times the upper limit of normal [ULN]) have been reported in approximately 1% of NSAID-treated patients in clinical trials. In addition, rare, sometimes fatal, cases of severe hepatic injury, including fulminant hepatitis, liver necrosis, and hepatic failure have been reported. Elevations of ALT or AST (less than three times ULN) may occur in up to 15% of patients treated with NSAIDs including ibuprofen. 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). If clinical signs and symptoms consistent with liver disease develop, or if systemic manifestations occur (e.g., eosinophilia, rash, etc.), discontinue COMBOGESIC immediately, and perform a clinical evaluation of the patient. COMBOGESIC has not been studied in patients with impaired hepatic function. The use of COMBOGESIC in patients with hepatic impairment is not recommended.

5.2 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 signs and/or 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 ibuprofen, increases the risk of serious gastrointestinal (GI) events [see Warnings and Precautions (5.3) ] . 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 (4) ] . 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 four years of follow-up. Avoid the use of COMBOGESIC in patients with a recent MI unless the benefits are expected to outweigh the risk of recurrent CV thrombotic events. If COMBOGESIC is used in patients with a recent MI, monitor patients for signs of cardiac ischemia.

5.3 Gastrointestinal Bleeding, Ulceration, and Perforation NSAIDs, including the ibuprofen in COMBOGESIC tablets, can cause serious gastrointestinal (GI) adverse events including inflammation, bleeding, ulceration, and perforation of the esophagus, 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 3-6 months, and in about 2-4% of patients treated for one year. However, even short-term therapy is not without risk. Risk Factors for Bleeding, Ulceration, and Perforation Patients with a prior history of peptic ulcer disease and/or gastrointestinal bleeding who used NSAIDs had a greater than 10-fold increased risk for developing a GI bleed compared to patients without these risk factors. Other factors that increase the risk of GI bleeding in patients treated with NSAIDs include longer duration of NSAID therapy, concomitant use of oral corticosteroids, aspirin, anticoagulants, or selective serotonin reuptake inhibitors (SSRIs); smoking; use of alcohol; older age; and poor general health status. […]

The following clinically significant adverse reactions to ibuprofen or acetaminophen are described elsewhere in other sections of the labelling. Hepatotoxicity [see Warnings and Precautions (5.1) ] Cardiovascular Thrombotic Events [see Warnings and Precautions (5.2) ] Gastrointestinal Bleeding, Ulceration, and Perforation [see Warnings and Precautions (5.3) ] Hypertension [see Warnings and Precautions (5.4) ] Heart Failure and Edema [see Warnings and Precautions (5.5) ] Renal Toxicity and Hyperkalemia [see Warnings and Precautions (5.6) ] Anaphylaxis and Other Hypersensitivity Reactions [see Warnings and Precautions (5.7) ] Serious Skin Reactions [see Warnings and Precautions (5.9) ] Hematologic Toxicity [see Warnings and Precautions (5.12) ] The most common adverse reactions (incidence of ≥ 2% for patients receiving COMBOGESIC) are: nausea, vomiting, headache, dizziness, somnolence, post-procedural hemorrhage, and swelling of the face (Table 1). The most common adverse reactions (greater than or equal to 2%) are nausea, vomiting, headache, dizziness, somnolence, post-procedural hemorrhage, and swelling of the face ( 6 ). To report SUSPECTED ADVERSE REACTIONS, contact Hikma Pharmaceuticals USA Inc. at 1-877-845-0689 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

6.1 Clinical Trials Experience Because clinical trials are conducted under varying conditions, adverse reaction rates observed in the clinical trials of one drug cannot be directly compared to the rates reported from clinical trials of another drug and may not reflect the rates observed in practice. The clinical trials of COMBOGESIC have been conducted in patients with postoperative pain following dental and arthroscopic procedures, who received double-blind treatment every 6 hours for 24 or 48 hours. Most commonly (≥2%) reported adverse reactions by organ system during double-blind treatment are listed in the table below. Adverse reactions are closely related to the extent (the level and length) of exposure. The incidences of overall and individual adverse reactions reported during the double-blind treatment period did not suggest an increase of risks associated with short-term (up to one or two days) use of the combination drug, COMBOGESIC in comparison to each individual component, acetaminophen or ibuprofen, and to placebo. Table 1: Most commonly (≥2%) reported adverse reactions by organ system during double-blind treatment COMBOGESIC Acetaminophen Ibuprofen Placebo N=261 N=231 N=231 N=199 Total number of AEs 145 142 101 133 % of patients with ≥1 AE 30 38 29 37 Gastrointestinal disorders Nausea 15 19 12 23 Vomiting 7 10 3 10 Constipation 1 2 1 1 Dyspepsia 0.4 1 2 1 Injury, poisoning and procedural complications Post Procedural Hemorrhage 2 0.4 1 2 Nervous system disorders Headache 5 6 4 7 Dizziness 3 4 4 5 Somnolence 2 1 0 1 Skin and subcutaneous tissue disorders Swelling face 2 4 4 3 Pruritus 0.4 0.4 0.4 3

6.2 Postmarketing Experience The following adverse reactions have been identified during postapproval use of acetaminophen and ibuprofen. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Skin and Appendages: Exfoliative dermatitis, Stevens-Johnson Syndrome (SJS), toxic epidermal necrolysis (TEN), and fixed drug eruption (FDE).

Table 2: Clinically Significant Drug Interactions with COMBOGESIC Drugs That Interfere with Hemostasis Clinical Impact: Ibuprofen and anticoagulants such as warfarin have a synergistic effect on bleeding. The concomitant use of ibuprofen and anticoagulants have an increased risk of serious bleeding compared to the use of either drug alone. Serotonin release by platelets plays an important role in hemostasis. Case-control and cohort epidemiological studies showed that concomitant use of drugs that interfere with serotonin reuptake and an NSAID may potentiate the risk of bleeding more than an NSAID alone. Intervention: Monitor patients with concomitant use of COMBOGESIC with anticoagulants (e.g., warfarin), antiplatelet agents (e.g., aspirin), selective serotonin reuptake inhibitors (SSRIs), and serotonin norepinephrine reuptake inhibitors (SNRIs) for signs of bleeding [ see Warnings and Precautions (5.12) ]. Aspirin Clinical Impact: Controlled clinical studies showed that the concomitant use of NSAIDs and analgesic doses of aspirin does not produce any greater therapeutic effect than the use of NSAIDs alone. In a clinical study, the concomitant use of an NSAID and aspirin was associated with a significantly increased incidence of GI adverse reactions as compared to use of the NSAID alone [ see Warnings and Precautions (5.3) ]. Intervention: Concomitant use of COMBOGESIC and analgesic doses of aspirin is not generally recommended because of the increased risk of bleeding [ see Warnings and Precautions (5.3) ]. COMBOGESIC is not a substitute for low dose aspirin for cardiovascular protection. ACE Inhibitors, Angiotensin Receptor Blockers, and Beta-Blockers Clinical Impact: NSAIDs may diminish the antihypertensive effect of angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), or beta-blockers (including propranolol). In patients who are elderly, volume-depleted (including those on diuretic therapy), or have renal impairment, co-administration of an NSAID with ACE inhibitors or ARBs may result in deterioration of renal function, including possible acute renal failure. These effects are usually reversible. Intervention: During concomitant use of COMBOGESIC and ACE-inhibitors, ARBs, or beta-blockers, monitor blood pressure to ensure that the desired blood pressure is obtained. During concomitant use of COMBOGESIC and ACE-inhibitors or ARBs in patients who are elderly, volume-depleted, or have impaired renal function, monitor for signs of worsening renal function [ see Warnings and Precautions (5.6) ] . When these drugs are administered concomitantly, patients should be adequately hydrated. Assess renal function at the beginning of the concomitant treatment and periodically thereafter. Diuretics Clinical Impact: Clinical studies, as well as post-marketing observations, showed that NSAIDs reduced the natriuretic effect of loop diuretics (e.g., furosemide) and thiazide diuretics in some patients. This effect has been attributed to the NSAID inhibition of renal prostaglandin synthesis. Intervention: During concomitant use of COMBOGESIC with diuretics, observe patients for signs of worsening renal function, in addition to assuring diuretic efficacy including antihypertensive effects [ see Warnings and Precautions (5.4 and 5.6) ]. Digoxin Clinical Impact: The concomitant use of ibuprofen with digoxin has been reported to increase the serum concentration and prolong the half-life of digoxin. Intervention: During concomitant use of COMBOGESIC and digoxin, monitor serum digoxin levels. Lithium Clinical Impact: NSAIDs have produced elevations in plasma lithium levels and reductions in renal lithium clearance . The mean minimum lithium concentration increased 15%, and the renal clearance decreased by approximately 20%. This effect has been attributed to NSAID inhibition of renal prostaglandin synthesis. Intervention: During concomitant use of COMBOGESIC and lithium, monitor patients for signs of lithium toxicity. Methotrexate Clinical Impact: Concomitant use of NSAIDs and methotrexate may increase the risk for methotrexate toxicity (e.g., neutropenia, thrombocytopenia, renal dysfunction). Intervention: During concomitant use of COMBOGESIC and methotrexate, monitor patients for methotrexate toxicity. Cyclosporine Clinical Impact: Concomitant use of NSAIDS and cyclosporine may increase cyclosporine's nephrotoxicity. Intervention: During concomitant use of COMBOGESIC and cyclosporine, monitor patients for signs of worsening renal function. NSAIDs and Salicylates Clinical Impact: Concomitant use of ibuprofen with other NSAIDs or salicylates (e.g., diflunisal, salsalate) increases the risk of GI toxicity, with little or no increase in efficacy [ see Warnings and Precautions (5.3) ] . Intervention: The concomitant use of ibuprofen with other NSAIDs or salicylates is not recommended. Pemetrexed Clinical Impact: Concomitant use of NSAIDS and pemetrexed may increase the risk of pemetrexed-associated myelosuppression, renal, and GI toxicity (see the pemetrexed prescribing information). Intervention: During concomitant use of COMBOGESIC and pemetrexed, in patients with renal impairment whose creatinine clearance ranges from 45 to 79 mL/min, monitor for myelosuppression, renal and GI toxicity. NSAIDs with short elimination half-lives (e.g., diclofenac, indomethacin) should be avoided for a period of two days before, the day of, and two days following administration of pemetrexed. In the absence of data regarding potential interaction between pemetrexed and NSAIDs with longer half-lives (e.g., meloxicam, nabumetone), patients taking these NSAIDs should interrupt dosing for at least five days before, the day of, and two days following pemetrexed administration. A number of known or potential interactions between COMBOGESIC and other drugs/drug classes exist. Please refer to the Drug Interactions section ( 7 ) for further information.

Infertility: NSAID-containing products, including COMBOGESIC, are associated with reversible infertility. Consider withdrawal of COMBOGESIC tablets in women who have difficulties conceiving. ( 8.3 ) Renal or hepatic impairment: Not recommended ( 5.1 , 5.6 , 8.6 , 8.7 ).

8.1 Pregnancy Risk Summary Ibuprofen Use of NSAID-containing products, including COMBOGESIC, 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 COMBOGESIC use between about 20 and 30 weeks of gestation and avoid COMBOGESIC use at about 30 weeks of gestation and later in pregnancy (see Clinical Considerations , Data ). Premature Closure of Fetal Ductus Arteriosus: Use of NSAID-containing products, including COMBOGESIC, at about 30 weeks gestation or later in pregnancy increases the risk of premature closure of the fetal ductus arteriosus. Oligohydramnios/Neonatal Renal Impairment: Use of NSAID-containing products, including COMBOGESIC, at about 20 weeks gestation or later in pregnancy has been associated with cases of fetal renal dysfunction leading to oligohydramnios, and in some cases, neonatal renal impairment. Data from observational studies regarding other potential embryofetal risks of NSAID use in women in the first or second trimester of pregnancy are inconclusive. In published animal reproduction studies, there were no clear developmental effects at doses up to 2.7-times the maximum human daily dose (MHDD) in the rabbit and 1.5-times in the MHDD rat when dosed throughout gestation. In contrast, an increase in membranous ventricular septal defects was reported in rats treated on Gestation Days 9 & 10 with 2.2-times the MHDD. Based on animal data, prostaglandins have been shown to have an important role in endometrial vascular permeability, blastocyst implantation, and decidualization. In animal studies, administration of prostaglandin synthesis inhibitors such as ibuprofen, resulted in increased pre- and post-implantation loss. Prostaglandins also have been shown to have an important role in fetal kidney development. In published animal studies, prostaglandin synthesis inhibitors have been reported to impair kidney development when administered at clinically relevant doses. Acetaminophen Prolonged experience with acetaminophen in pregnant women over several decades, based on published observational epidemiological studies and case reports, did not identify a drug associated risk of major birth defects, miscarriage or other adverse maternal or fetal outcomes (see Data ) . Reproductive and developmental studies in rats and mice from the published literature have identified adverse events at clinically relevant doses of acetaminophen. Fetotoxicity, increases in bone variations in the fetuses, and necrosis in the fetus liver and kidney have been noted in studies in rats. In mice treated with acetaminophen at doses within the clinical dosing range, cumulative adverse effects on reproduction were seen in a continuous breeding study. A reduction in number of litters of the parental mating pair was observed as well as retarded growth and abnormal sperm in their offspring and reduced birth weight in the next generation. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Clinical Considerations Fetal/Neonatal Adverse Reactions Premature Closure of Fetal Ductus Arteriosus: Avoid use of NSAID-containing products, including COMBOGESIC, in women at about 30 weeks gestation and later in pregnancy, because NSAID-containing products, including COMBOGESIC, can cause premature closure of the fetal ductus arteriosus (see Data ) . Oligohydramnios/Neonatal Renal Impairment: If, after consideration of alternative treatments for pain management, an NSAID-containing product, including COMBOGESIC, is necessary at about 20 weeks gestation or later in pregnancy, limit the use to the lowest effective dose and shortest duration possible. If COMBOGESIC treatment extends beyond 48 hours, consider monitoring with ultrasound for oligohydramnios. If oligohydramnios occurs, discontinue COMBOGESIC and follow up according to clinical practice (see Data ). Labor or Delivery There are no studies on the effects of COMBOGESIC during labor or delivery. In animal studies, NSAIDs, including ibuprofen, inhibit prostaglandin synthesis, cause delayed parturition, and increase the incidence of stillbirth. Data Human Data Ibuprofen: Premature Closure of Fetal Ductus Arteriosus Published literature reports that the use of NSAIDs at about 30 weeks of gestation and later in pregnancy may cause premature closure of the fetal ductus arteriosus. Oligohydramnios/Neonatal Renal Impairment Published studies and postmarketing reports describe maternal NSAID use at about 20 weeks gestation or later in pregnancy associated with 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. In many cases, but not all, the decrease in amniotic fluid was transient and reversible with cessation of the drug. There have been a limited number of case reports of maternal NSAID use and neonatal renal dysfunction without oligohydramnios, some of which were irreversible. Some cases of neonatal renal dysfunction required treatment with invasive procedures, such as exchange transfusion or dialysis. Methodological limitations of these postmarketing studies and reports include lack of a control group; limited information regarding dose, duration, and timing of drug exposure; and concomitant use of other medications. These limitations preclude establishing a reliable estimate of the risk of adverse fetal and neonatal outcomes with maternal NSAID use. Because the published safety data on neonatal outcomes involved mostly preterm infants, the generalizability of certain reported risks to the full-term infant exposed to NSAIDs through maternal use is uncertain. Acetaminophen: The results from a large population-based prospective cohort, including data from 26,424 women with live born singletons who were exposed to oral acetaminophen during the first trimester, indicate no increased risk for congenital malformations, compared to a control group of unexposed children. The rate of congenital malformations (4.3%) was similar to the rate in the general population. A population-based, case-control study from the National Birth Defects Prevention Study showed that 11,610 children with prenatal exposure to acetaminophen during the first trimester had no increased risk of major birth defects compared to 4,500 children in the control group. Other epidemiological data showed similar results. However, these studies cannot definitely establish the absence of any risk because of methodological limitations, including recall bias. Animal Data Ibuprofen: In a published study, female rabbits given 7.5, 20, or 60 mg/kg ibuprofen (0.12, 0.33, or 0.99-times the maximum human daily dose of 1170 mg of ibuprofen based on a body surface area comparison) from Gestation Days 1 to 29, no clear treatment-related adverse developmental effects were noted. This dose was associated with significant maternal toxicity (stomach ulcers, gastric lesions). In the same publication, female rats were administered 7.5, 20, 60, 180 mg/kg ibuprofen (0.06, 0.17, 0.50, 1.5-times the maximum daily dose) did not result in clear adverse developmental effects. […]

Analgesia COMBOGESIC contains acetaminophen and ibuprofen. Acetaminophen is a non-opiate, non-salicylate analgesic. The precise mechanism of the analgesic properties of acetaminophen is not established but is thought to primarily involve central actions. Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID). Its mechanism of action for analgesia, like that of other NSAIDs, is not completely understood, but involves inhibition of cyclooxygenase (COX-1 and COX-2). Ibuprofen is a potent inhibitor of prostaglandin synthesis in vitro. Prostaglandins sensitize afferent nerves and potentiate the action of bradykinin in inducing pain in animal models. Prostaglandins are mediators of inflammation. Because ibuprofen is an inhibitor of prostaglandin synthesis, its mode of action may be due to a decrease of prostaglandins in peripheral tissues.