Diflunisal: six-month experience in osteoarthritis

Diflunisal compared with naproxen in the treatment of dysmenorrhea

A randomized double-blind cross-over study was carried out in 19 young female undergraduates with severe primary dysmenorrhea to compare the efficacy and tolerance of treatment with diflunisal and naproxen. All patients received both substances twice during four consecutive cycles. The first tablet was taken at the onset of dysmenorrheic symptoms and continued according to the individual need, maximally four tablets daily. The overall relieving effect was good or moderate in 73.7% of the diflunisal cycles and in 92.1% of the naproxen cycles. The difference was not statistically significant. One third of the women estimated decreased menstrual blood loss during treatment with both the drugs. Side effects were mild and did not cause discontinuation of the therapy. Diflunisal seems to be as equally effective in the treatment of primary dysmenorrhea as naproxen, which is a well-documented and widely used prostaglandin synthetase inhibitor.

Diflunisal 500-750 mg versus aspirin 2600-3900 mg in the treatment of rheumatoid arthritis

Diflunisal was compared to aspirin in a 12-week, double-blind, parallel, multicenter rheumatoid arthritis study. One hundred twenty-six (126) patients received diflunisal and 123 patients received aspirin. Both treatment groups demonstrated significant improvement from baseline in joint pain, morning stiffness, grip strength, walking time and painful and swollen joint scores. For these parameters, the only statistically significant difference between the groups was that diflunisal was more effective than aspirin for overall joint pain at week 2. The overall evaluation by patients and by investigators showed significantly better responses in those treated with diflunisal at weeks 1 and 12. Diflunisal produced significantly less gastrointestinal pain and tinnitus than aspirin. Neither drug showed unusual frequency of adverse effects as determined in the laboratory. Long-term studies using a higher-dose regimen are suggested to further define the efficacy and tolerability of diflunisal in the treatment of patients with rheumatoid arthritis.

A 12-hour evaluation of the analgesic efficacy of diflunisal, aspirin, and placebo in postoperative dental pain

Two-hundred and one outpatients with postoperative pain following oral surgery were randomly assigned, on a double-blind basis, a single oral dose of diflunisal (250, 500, or 1000 mg), aspirin (650 mg), or placebo. Using a self-rating record, the subjects rated their pain and its relief hourly for 12 hours after medication. Measures of peak and total analgesia were derived from the patients' subjective reports. Diflunisal 250 and 1000 mg were significantly superior to aspirin for every measure of total and peak analgesia; the 500-mg diflunisal dose was significantly superior to aspirin for measures of total analgesia only. All doses of diflunisal were significantly superior to aspirin and placebo at each hour from hour 3 through hour 12. Approximately 60 per cent of the patients treated with diflunisal completed the 12-hour observation period without the need for additional analgesic therapy. Adverse effects were mild and transitory and occurred in less than 10 per cent of the patients.

The effect of diflunisal on hyaluronic acid production by 'activated' human synovial fibroblasts

1 Cultured human synovial fibroblasts were 'activated' by leucocytes or poly (I) . poly (C) to overproduce hyaluronic acid. 2 Diflunisal in concentrations of 30, 15 and 10 microgram/ml completely abrogated the overproduction of hyaluronic acid induced by leucocytes. 3 Diflunisal (10 microgram/ml), indomethacin (2 microgram/ml) and aspirin (200 microgram/ml) partially inhibited the overproduction of hyaluronic acid induced by poly (I) . poly (C), although none of them decreased it to control non 'activated' levels. 4 Diflunisal 25 microgram/ml completely abrogated hyaluronic acid overproduction induced by poly (I) . poly (C). 5 This model could be an in vitro indicator for in vivo pharmacological levels of anti-inflammatory drugs.

Diflunisal in rheumatoid arthritis

In an eight-week double-blind study comparing the new long-acting aspirin derivative, diflunisal, in doses up to 1 g/day with aspirin in doses up to 4 g/day in 16 patients with classical or definite rheumatoid arthritis, diflunisal was more effective in reducing the total articular index (Ritchie) and erythrocyte sedimentation rate and in increasing grip strength. Diflunisal had an earlier effect on erythrocyte sedimentation rate than antiinflammatory doses of aspirin. Patients on diflunisal experienced fewer side effects than patients on aspirin. Ten patients with rheumatoid arthritis who previously participated in the eight-week study comparing diflunisal to aspirin (five patients from each group) were continued on 1 g diflunisal per day for six months. The efficacy of diflunisal therapy persisted during a six-month period, and there were no side effects. The switchover from 4g aspirin to 1g diflunisal a day was accompanied by further improvement in the Ritchie total score, erythrocyte sedimentation rate, and grip strength and by disappearance of side effects. Diflunisal 1 g/day proved to be an efficient and well-tolerated drug in patients with rheumatoid arthritis.

High-pressure liquid chromatographic determination of acetylsalicylic acid, salicylic acid, diflunisal, indomethacin, indoprofen and indobufen

A high-pressure liquid chromatographic technique was developed which allowed concurrent measurement of acetylsalicylic acid (ASA) and salicylic acid (SA) in plasma. ASA was extensively deacetylated to SA not only in vivo but also in vitro, even in frozen plasma. The in vitro conversion could be prevented by physostigmine. In vivo, ASA was eliminated within few hours, whereas SA was continuously present following daily administration of conventional doses of ASA. A slight modification of a similar method, originally developed for naproxen determination [9], was found appropriate for measurement of the SA derivative diflunisal, of two non-SA antiinflammatory agents, indomethacin and indoprofen, and of a related anti-platelet agent, indobufen.

Diflunisal: a review of its pharmacological properties and therapeutic use in pain and musculoskeletal strains and sprains and pain in osteoarthritis

Diflunisal is a salicylic acid derivative with analgesic and anti-inflammatory activity. It has been studied in osteoarthritis, pain resulting from musculoskeketal sprains and strains and from minor surgery and cancer. The duration of its analgesic effect is longer than that of aspirin and diflunisal is effective when given twice daily. Diflunisal is not metabolised to salicylic acid and has a lesser effect than aspirin on platelet function in vivo. In osteoarthritis, diflunisal appears comparable in efficacy to moderate doses of aspirin (2 to 3g daily), but is better tolerated. It has not been compared with the most active phenylalkanoic acid derivatives such as naproxen in adequate numbers of patients. Diflunisal is comparable with glafenine in pain and with propoxyphene/paracetamol combinations and oxyphenbutazone in pain and in musculoskeletal strains and sprains. As with other non-steroidal agents, gastrointestinal complaints are the most frequently reported side effects.

Diflunisal, a new analgesic, in the treatment of postoperative pain following removal of impacted mandibular third molars

Diflunisal, 5-(2', 4'-difluorophenyl) -salicylic acid, has been shown in animal and human studies to possess pronounced analgesic and anti-inflammatory effects. The objective of the present investigation wa to compare the analgesic effect and safety of three doses of 500 mg diflunisal, given orally over 36 h, with placebo in the treatment of pain following surgical removal of impacted mandibular third molars. A total of 60 patients, 30 patients in each treatment group, participated in this double-blind, completely randomized study. The treatment groups were compared for demographic data, disease-related variables and pretreatment severity of pain. According to both the investigator's and the patient's overall evaluation of treatment efficacy on postoperative pain, diflunisal was significantly better than placebo (P less than 0.0001). Clinical adverse reactions were reported by seven patients (25%) in the diflunisal group compared to three patients (11%) in the control group. In two instances the adverse reactions were rated by the investigator to have been "unacceptable". The overall conclusion of this study is that diflunisal, compared to placebo, is a highly effective and well-tolerated analgesic in the treatment of postoperative pain following surgical removal of impacted mandibular third molars.

Post-operative analgesia with diflunisal

An open study was carried out in 196 consecutive patients who had undergone orthopaedic (103) or gynaecological (93) surgical procedures to assess the effectiveness and tolerability of a single dose of 500 mg diflunisal in the relief of postoperative pain. Diflunisal was given when patients first complained of pain, and pain severity before and at intervals up to 6 hours after the dose was assessed using a 10-point analogue scale. The results showed that diflunisal was both prompt and prolonged in its effect. No pain was reported after 1 hour in 138 (71%) of the 196 patients, and after 6 hours only 13 (7%) still reported some pain. Diflunisal was equally as effective in the two groups. Side-effects were reported in 13 (7%) patients but these were ones commonly found in the post-operative situation.

Diflunisal, a new-acting analgesic and prostaglandin inhibitor: effect of concomitant acetylsalicylic acid therapy on ototoxicity and on disposition of both drugs

Intermittent and concomitant acetylsalicylic acid (ASA) therapy was superimposed onto a 21-day regimen with diflunisal 250 mg b.i.d. Low doses of ASA (600 mg single dose or 300 mg q.i.d.) did not influence signficantly diflunisal blood levels whereas a 600 mg q.i.d. dosing caused a small significant drop, especially at trough level. This drop is not expected to be clinically significant. No ototoxicity could be demonstrated with any treatment of diflunisal though four of fourteen subjects reported mild tinnitus during concomitant therapy at the higher doses of ASA. Diflunisal at 375 mg b.i.d. failed to alter the metabolism of a single dose of labelled ASA (600 mg) as judged by plasma levels, urinary excretion and plasma binding. Daily urinary excretion of prostaglandins E1 and E2 major metabolite was decreased by about 70% by diflunisal.

Diflunisal in the treatment of osteoarthrosis: a double-blind study comparing diflunisal with ibuprofen

A double-blind trial was carried out in 37 patients with osteoarthrosis to compare the efficacy and tolerance of 250 mg diflunisal twice daily with that of 400 mg ibuprofen 3-times daily over an 8-week period. Rating scale assessments were made, at the end of a preceding 1-week, wash-out period on placebo and at regular fixed intervals, of weight-bearing pain, night pain, a specific functional activity, and of the duration of inactivity stiffness. Patients' and physician's overall evaluations of response, taking side-effects into account, were made on completion of the study. The data collected indicated that in 30 patients completing the trial both treatments produced similar overall results and, with the exception of weight-bearing pain which appeared to be improved more in the ibuprofen group, diflunisal provided equal therapeutic benefit with fewer side-effects.

A controlled study of diflunisal in sprains and strains

A preliminary double-blind, randomized trial was carried out in general practice to compare the efficacy of treatment with diflunisal (500 mg) twice daily and a combination of dextropropoxyphene (65 mg) plus paracetemol (650 mg) 3-times daily for 3 days in relieving pain associated with strains and sprains. Analysis of the results from 51 patients showed that both treatments were equally effective in releiving spontaneous pain and pain on movement after 1 and 3 days, and there were no differences between the two groups in patients' overall evaluation of treatment or physicians' assessment of therapeutic response. Both treatments were well tolerated during the short-term period of the trial.

Diflunisal compared with naproxen in the treatment of osteoarthrosis of hip or knee: a double-blind trial

A randomized double-blind trial was carried out in 20 patients with osteoarthrosis of the hip or knee to compare the efficacy and tolerance of treatment with diflunisal or naproxen. During the first 4 weeks, patients received either 250 mg diflunisal or 250 mg naproxen twice daily and this was increased by 250 mg daily in 5 patients on diflunisal and in 3 on naproxen for the second 4 weeks of the trial. The results of subjective assessments made before and at the end of Week 8 showed a trend in favour of diflunisal for improvement of symptoms, except for weight-bearing pain which was improved in only 1 patient in each group. More of the patients receiving diflunisal than naproxen considered treatment to have been satisfactory, and rated their response as equally as good as or better than previous medication. Diflunisal produced significantly high incidence of gastro-intestinal upsets, leading to the withdrawal of 2 patients at Week 4.

Two trials of diflunisal in osteoarthritis

Two double-blind inter-group trials were carried out in which diflunisal was compared for 12 weeks against aspirin in 30 patients with osteoarthritis of knees or hips, and against naproxen for 8 weeks in 20 patients with osteoarthritic knees. Diflunisal appeared to be somewhat better than aspirin in terms of both effectiveness and tolerance, whilst it was similar in both repects to naproxen.

Diflunisal in the management of sprains

A double-blind randomized trial was carried out in 31 patients suffering from acute, minor ligamentous injuries to compare the efficacy of diflunisal in the relief of pain with that of oxyphenbutazone. Patients received either 500 mg diflunisal twice daily or 200 mg oxyphenbutazone 3-times daily for 3 days. The results of subjective assessments showed tha by Day 3 spontaneous pain had either completely resolved or markedly improved in all patients, and that diflunisal was significantly better than oxyphenbutazone on Days 1 and 3 in relieving pain on movement of the joint.

Relationship of plasma salicylate levels to pain relief with two different salicylates

In a preliminary open study of salsalate (3 g daily for 4 weeks) in 61 patients with rheumatoid arthritis or osteoarthrosis, it was found that although the drug produced satisfactory analgesia in 64% of patients, the incidence of side-effects was high (57% of patients): most were symptoms of salicylism and probably related to the high plasma salicylate levels achieved. In a second open study, 20 patients with osteoarthrosis were treated for 4 weeks with 250 mg diflunisal twice daily and then crossed over to salsalate (3 g daily) for a further 2 weeks. The results of subjective assessments of pain relief showed that both drugs produced satisfactory analgesia, and neither was associated with a significant level of gastro-intestinal bleeding. During the diflunisal treatment period there were no reports of salicylism, and plasma salicylate levels were very much lower than those measured after salsalate. The pain relieving effects of both drugs, assessed from patient preference for one or the other treatment, were unrelated to the plasma salicylate levels and it is suggested that plasma levels may have more relationship to the incidence of side-effects than with therapeutic effects.