The effects of ibuprofen, indomethacin, aspirin, naproxen, and placebo on the gastric mucosa of normal volunteers: a gastroscopic and photographic study

Protection against aspirin-induced antral and duodenal damage with enprostil. A double-blind endoscopic study

Prostaglandins protect against aspirin-induced damage to the gastrointestinal tract. This study tested the ability of enprostil, a synthetic analog of prostaglandin E2, given concurrently to prevent gastroduodenal injury. Twenty-four healthy subjects were randomly assigned to one of three groups. All received aspirin 650 mg q.i.d. for 5 days. One group received placebo and the other groups were given either 7 or 70 micrograms of enprostil b.i.d. for 5 days. Upper endoscopy was performed at entry and 2 h after the final dose of aspirin. Enprostil 70 micrograms b.i.d. afforded significant protection of both the antral and duodenal mucosa. The 7-micrograms dose protected only the antral mucosa. Side effects were not observed with the lower dose of enprostil. Serum salicylate levels did not differ significantly between the groups.

Endoscopic studies of gastric and duodenal injury after the use of ibuprofen, aspirin, and other nonsteroidal anti-inflammatory agents

The toxic effects of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) were endoscopically evaluated in several studies conducted between 1975 and 1983 and involving 843 normal volunteers. Anti-inflammatory doses of acetylsalicylic acid (2,400 and 3,900 mg/day) consistently produced significantly more mucosal injury than did any of the newer NSAIDs. Buffering did not reduce the degree of damage. Little or no mucosal injury was seen with placebo, "pro drugs," enteric-coated aspirin, or 1,200 mg/day of ibuprofen (Motrin, Upjohn). However, varying degrees of generally dose-dependent mucosal injury were evident with larger doses of ibuprofen, naproxen, tolmetin sodium, and indomethacin. The amount of mucosal damage after 2,400 mg/day of ibuprofen did not increase when 4,800 mg daily was administered. Duodenal injury corresponded to gastric injury, but it was generally less severe. Short-term studies of one to three days indicated that ibuprofen produced little or no injury when given at a dose of 2,400 mg for one day or 1,600 mg/day for three days. No relation was noted between subjective symptoms and endoscopic findings.

Gastrointestinal microbleeding associated with the use of etodolac, ibuprofen, indomethacin, and naproxen in normal males

Etodolac, a nonsteroidal antiinflammatory and analgesic drug, was used in a randomized, parallel group, open-label design study, with stool analysis conducted in a blind fashion, to compare its effect in normal men in doses of 400 mg (N = 11) and 600 mg (N = 12) b.i.d. on gastrointestinal microbleeding with that of 600 mg ibuprofen, q.i.d. (N = 12), 50 mg indomethacin in the morning, 50 mg at noon, and 100 mg h.s. (N = 9), and 375 mg naproxen b.i.d. (N = 9). Etodolac was given at about 2 1/2 and 3 1/2 times the mean effective dose used for treating patients with rheumatoid arthritis. The other drugs were given at their manufacturers' maximum recommended doses. Lead-in placebo was given for one week, active drug for one week, and washout placebo for one week. Fecal blood loss was measured by the 51Cr-tagged red cell method, and was averaged over days 4-7 (baseline), 11-14 (treatment period), and 17-20 (washout). The mean increase in blood loss for the treatment period for the 400 mg etodolac b.i.d. group (0.13 ml) and 600 mg etodolac b.i.d. group (0.10 ml) was significantly less (P = 0.001) than the corresponding values for ibuprofen (1.14 ml), indomethacin (1.20 ml), and naproxen (0.87 ml). There was no tendency for greater blood loss at higher doses of etodolac. Etodolac at doses in excess of the mean effective dose in osteoarthritis and rheumatoid arthritis caused significantly less microbleeding in normal male volunteers during the seven-day treatment period than the other drugs tested, and not clinically more than that occurring during baseline placebo.

Non-steroidal anti-inflammatory drugs. Current status and rational therapeutic use

Aspirin (acetylsalicylic acid), the first of the NSAIDs (introduced in 1899), was initially never referred to as an anti-inflammatory agent. It was the advent of cortisone in 1949 that demonstrated dramatically that corticosteroids had anti-inflammatory properties and the term 'non-steroidal anti-inflammatory drug' was first used when phenylbutazone was introduced 3 years later. Since then, the NSAIDs have proliferated. There is to date no good evidence that they halt progression of rheumatoid disease, but by easing pain and diminishing swelling they make life much easier in osteoarthrosis, rheumatoid arthritis and many other types of arthritis, and are the drugs of first choice in acute gout. Their mode (or modes) of action are obscure and though inhibition of cyclo-oxygenase (prostaglandin synthetase) is clearly important, other mechanisms are also involved. The assessment of the anti-inflammatory action of these agents has received considerable attention in clinical trials because, whatever their action may be in experimental animal models, their action in inflamed joints in human patients must be ascertained, since there may be little parallel between the two. Different experimental animal models give different results with various agents and often bear little relation to their therapeutic action in man. No attempt has been made here to review in depth all the NSAIDs that have appeared since 1952. All have anti-inflammatory and analgesic activity and all can cause gastrointestinal side effects, though effectiveness and toxicity vary from drug to drug and patient to patient, there being very great interpatient variability. Non-reactors, patients who apparently fail to respond to certain agents, need further study, for it seems that these subjects may metabolise these agents differently from others. Considerable ingenuity has been shown not only in evolving new NSAIDs but in finding new ways of administering them. The number and variety of NSAIDs in their various forms varies greatly from country to country, depending largely on the regulatory bodies of those countries. In the meantime, the search for a better, less toxic compound continues with the hope that one may be found which has a deeper and more basic action on the underlying disease process.

A controlled endoscopic study comparing the toxic effects of sulindac, naproxen, aspirin, and placebo on the gastric mucosa of health volunteers

Sixty volunteers were endoscopically evaluated to compare gastric mucosal injury following oral administration of sulindac, naproxen, aspirin, or placebo for two consecutive seven-day periods. A single-blind technique was utilized wherein the endoscopist was unaware which drug each volunteer had received. The following dosages were employed for the two study periods: sulindac, 150 and 200 mg, b.i.d., naproxen, 250 and 375 mg, b.i.d., and aspirin, 650 and 975 mg, q.i.d. The only subject who developed a frank ulcer with mucosal bleeding was in the sulindac group, however volunteers taking sulindac demonstrated statistically less significant mucosal injury on endoscopic examination than those receiving naproxen or aspirin.

The argument for aspirin as the NSAID of choice in the management of rheumatoid arthritis

In view of their costliness, the use of newer NSAIDs is justified if they are demonstrably more effective, less toxic, or better tolerated than aspirin (ASA). However, there is no evidence that any is more effective than ASA, and their widely assumed comparable effectiveness has not been demonstrated convincingly. In terms of clinically meaningful overt and even occult gastrointestinal blood loss, ASA is indistinguishable from the newer NSAIDs. Most NSAIDs evoke fewer unpleasant gastrointestinal symptoms than ASA does, although current recording of such symptoms has magnified the ASA experience. Prescribing a new NSAID before ASA requires a heuristic assertion of comparable effectiveness, misconception of overt toxicities, and belief in the meaningfulness of data demonstrating differential tolerance. The trade-off is increased expense and unknown long-term toxicity.

Gastrointestinal effects of antipyretic analgesics

Aspirin and paracetamol (acetaminophen) are the most commonly used minor analgesics, but their effects on the gastrointestinal tract differ widely. Aspirin is significantly associated with major upper gastrointestinal hemorrhage, whereas acetaminophen is not. Short-term use of aspirin produces erythema, erosions, and occasionally ulcers; acetaminophen use does not. Chronic gastric ulcer is linked to aspirin intake in patients with rheumatic disease, and epidemiologically in all heavy aspirin users; paradoxically, in only one epidemiologic study was a significant association found between acetaminophen intake and chronic gastric ulcer. Fecal occult blood loss is increased in most regular aspirin users but not in those taking acetaminophen. Although studies in children have not apparently been made, in isolated small clinical series it has been shown that gastrointestinal bleeding and anemia do occur in the pediatric age group following the use of aspirin. Pathophysiologically, aspirin alters the gastric mucosal barrier to hydrogen ions and lowers gastric potential difference; acetaminophen has no effect on these parameters. Such changes correlate ultrastructurally with damage in surface epithelial cells and microerosions after the use of aspirin, but not after the use of acetaminophen. Aspirin causes a dramatic reduction in the ability of gastric mucosa to generate protective prostaglandins; however, acetaminophen also reduces prostaglandins. Other postulated mechanisms of aspirin damage include reduction in gastric mucosal secretion, bicarbonate output, and alteration of cell turnover. Because aspirin damage to gastric mucosa is often "silent," the clinician needs a high level of suspicion and awareness. In patients prone to gastric damage, or in those with a past history of aspirin-induced gastric damage, acetaminophen is the drug of choice when a minor, noninflammatory problem requires an analgesic.

Effects of fenbufen, indomethacin, naproxen, and placebo on gastric mucosa of normal volunteers. A comparative endoscopic and photographic evaluation

The effects of fenbufen (1,000 mg a day), indomethacin (150 mg a day), naproxen (750 mg a day), and placebo on gastric mucosa were determined by endoscopy and recorded photographically. One hundred normal subjects, randomly divided into equal, parallel-treatment groups, were given the drugs in divided daily doses for seven consecutive days. The results revealed that the effects of fenbufen on gastric mucosa were significantly (p less than or equal to 0.05) less than those of either naproxen or indomethacin and not statistically different from those observed with placebo.

Effects of non-steroidal anti-inflammatory drugs and prostaglandins on alkali secretion by rabbit gastric fundus in vitro

The effects of non-steroidal anti-inflammatory drugs and prostaglandins E(2) and F(2alpha) on the secretory and electrical activity of isolated rabbit fundic mucosa have been studied. Spontaneous acid secretion was inhibited by serosal side application of sodium thiocyanate (6x10(-2)M) and the resulting alkali secretion measured by pH stat tiration. Serosal side application of indomethacin (10(-5)M) or aspirin (3x10(-3)M) inhibited alkali secretion (0.55+/-0.06 to 0.12+/-0.06 mumol/cm(2)/h, n=6, p<0.01 and 0.28+/-0.06 to 0.11+/-0.03 mumol/cm(2)/h, n=7, p<0.02 respectively). Mucosal or serosal side prostaglandin E(2) (10(-5) to 10(-10)M) and F(2alpha) (10(-4) to 10(-10)M) failed to alter the rate of alkalinisation but secretion was significantly increased by serosal side 16,16-dimethyl-prostaglandin E(2) (10(-6)M) (0.90+/-0.20 to 1.50+/-0.30 mumol/cm(2)/h, n=6, p<0.01). Serosal side application of 10(-6)M prostaglandin E(2) to fundic mucosae pretreated with either aspirin (5x10(-3)M) or indomethacin (10(-5)M), to reduce endogenous E(2) formation, also failed to alter alkali secretion. Pretreatment of the mucosa with 16,16-dimethyl-E(2) (10(-6)M) abolished the inhibitory effect of indomethacin (10(-5)M) on alkali secretion (n=6) but did not modify the secretory response to aspirin (3x10(-3)M) (fall in alkali secretion with aspirin = 81+/-11% and with aspirin plus 16,16-dimethyl-E(2) = 72+/-10%, n=7). In the doses used, none of the prostaglandins or non-steroidal anti-inflammatory drugs altered transmucosal potential difference or electrical resistance. These results show that the damaging agents, aspirin and indomethacin, both inhibit gastric alkali secretion but that modes of action may differ. The observation that prostaglandins, E(2) and F(2alpha) failed to increase alkali production suggests that their protective activity against a variety of damaging agents as shown by others, may be mediated by another mechanism.

Gastric adaptation occurs with aspirin administration in man

Endoscopy has become a standard method to evaluate drug-induced damage to the gastroduodenal mucosa; however, studies defining the time course, extent, and duration of the injury in man are unavailable. We report a systematic endoscopic evaluation of the effect of aspirin administration on the gastric mucosa in normal volunteers. Aspirin (2.6 g/ day) or placebo was administered for 1 or 7 days. Gastroscopy was performed after 1, 2, 4, and 8 days, and every other day thereafter until the lesions resolved. Submocosal hemorrhages and/or focal erosions were present within 24 hr in all subjects. With continuous aspirin administration, injury was maximal within 3 days and then lessened, ie, damage present after 7 days of aspirin was significantly less than after 1 day of therapy. The time to resolution of the damage was also longer following 1 day than after 7 days of aspirin (median 8 days for 1 day of aspirin vs median 3 days for 7 days of aspirin). Thus, gastric mucosal adaptation occurred and was associated both with less damage and with an accelerated healing process. Acute administration of aspirin produced well-defined areas of submucosal hemorrhages within 2 hr of administration; additional doses increased the area of involvement but not necessarily the severity of involvement.

Effects of 24 hours of aspirin, Bufferin, paracetamol and placebo on normal human gastroduodenal mucosa

Aspirin causes gastroduodenal erosions and/or ulcers in man when taken for prolonged periods. The effects of shorter periods of aspirin, Bufferin, or paracetamol (acetaminophen) intake as used for self-medication are unknown. In a four way, crossover, blinded endoscopic study, we compared the effects of aspirin, Bufferin, paracetamol, and placebo, two tablets four times a day for 24 hours, on the gastroduodenal mucosa of 10 normal volunteers. Both regular aspirin and bufferin produced multiple gastric (p less than 0.005) and duodenal erosions (p less than 0.05, compared with baseline and placebo studies). Paracetamol did not cause significant gastric or duodenal mucosal damage. Two subjects developed duodenal ulcer-like lesions in the course of the study. We conclude that the use of unbuffered aspirin and Bufferin, but not paracetamol, in recommended doses for one day causes significant gastroduodenal mucosal damage.

Do prostaglandins cause gastrointestinal mucosal injury?

We have reviewed various examples of the injurious effects of prostaglandins on the gastrointestinal tract along with evidence that, in certain disease states, nonsteroidal antiinflammatory agents may have a prophylactic or therapeutic effect. The most important areas in which these drugs may be useful are in treatment or prevention of esophagitis, food intolerance symptoms, cholera, radiation-induced diarrhea, and ulcerative colitis. Although these two sets of facts appear to be contradictory, they may actually represent two distinct phenomena. The examples of deleterious effects of prostaglandins on gastrointestinal mucosa are all examples of inflammatory changes. Many changes occur in acute inflammation, including leukocytosis and chemotaxis of neutrophils to the area of inflammation. Release of many substances, including prostaglandins, histamine and bradykinin, occurs into the inflamed site. The prostaglandins involved in inflammation of the gastrointestinal mucosa may be quite different in source, type, and quantity from endogenous prostaglandins which play a role in cytoprotection. In addition, because other substances in addition to prostaglandins are involved in inflammation, and nonsteroidal antiinflammatory agents do not act exclusively by inhibition of prostaglandin synthesis, the therapeutic benefit of antiinflammatory agents in gastrointestinal mucosa may be due to several mechanisms. Therefore, in spite of the strong evidence indicting nonsteroidal antiinflammatory drugs as occasionally harmful to the gastric, duodenal, and intestinal mucosa, we should not lose sight of their important potential therapeutic role in other areas of the gastrointestinal tract.

Gastroscopic evaluation of the effect of aspirin and oxaprozin on the gastric mucosa

Oxaprozin, a new long-acting, antiinflammatory agent, and aspirin were compared utilizing gastroscopic evaluation and photography of the gastric mucosa in a double-blind, crossover study in normal volunteers. Submucosal hemorrhages or mucosal bleeding was observed in seven of eight subjects on aspirin and in only two of eight on oxaprozin (P = 0.061). Adverse effects were experienced by seven of eight subjects after the aspirin treatment period--tinnitus in five and gastrointestinal symptoms in four. Only one patient had mild diarrhea on oxaprozin. The incidence of adverse effects was found significantly higher with aspirin therapy (P less than 0.001). No laboratory abnormalities of clinical significance were attributed to either drug administration. Results after ten days of treatment show that oxaprozin in therapeutic dose levels (1200 mg once a day) produces significantly fewer changes in the gastric mucosa than aspirin (975 mg administered four times a day, total daily dose 3.9 Gm) in the same subjects, who received both drugs in this double-blind, crossover experiment with a four-week washout period between treatments.

Endoscopic evaluation of gastric tolerance to fenclofenac

Gastrointestinal irritation is a common consequence of treatment with many non-steroidal anti-inflammatory agents. An open tolerance study with endoscopic control employing fenclofenac in doses of 900 or 1200 mg daily in ten patients with osteoarthrosis, was carried out over an eight week period. The principal aim of the study was to evaluate the effect of fenclofenac on the gastroduodenal mucosa in a selected group of patients with osteoarthrosis and with a history of gastric intolerance to other non-steroidal anti-inflammatory agents. All patients tolerated fenclofenac well and showed clinical improvement.