Pharmacokinetics and tolerance of slow-release indomethacin tablets in rheumatoid arthritis

Application of liposomes in treatment of rheumatoid arthritis: quo vadis

The most common treatments for rheumatoid arthritis include nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroids, disease modifying antirheumatic drugs (DMARDs), and some biological agents. However, none of the treatments available is able to achieve the ultimate goal of treatment, that is, drug-free remission. This limitation has shifted the focus of treatment to delivery strategies with an ability to deliver the drugs into the synovial cavity in the proper dosage while mitigating side effects to other tissues. A number of approaches like microemulsions, microspheres, liposomes, microballoons, cocrystals, nanoemulsions, dendrimers, microsponges, and so forth, have been used for intrasynovial delivery of these drugs. Amongst these, liposomes have proven to be very effective for retaining the drug in the synovial cavity by virtue of their size and chemical composition. The fast clearance of intra-synovially administered drugs can be overcome by use of liposomes leading to increased uptake of drugs by the target synovial cells, which in turn reduces the exposure of nontarget sites and eliminates most of the undesirable effects associated with therapy. This review focuses on the use of liposomes in treatment of rheumatoid arthritis and summarizes data relating to the liposome formulations of various drugs. It also discusses emerging trends of this promising technology.

The safety profile of sustained-release etodolac

The safety profile of a new sustained-release (SR) form of etodolac was evaluated in 539 young and elderly patients with osteoarthritis or rheumatoid arthritis. Four long-term, open-label studies were conducted in nine different countries totaling 3,827 patient-months' exposure to etodolac SR. Patients were treated with either 400 mg or 600 mg etodolac SR once a day for up to 52 weeks. Withdrawals due to adverse reactions were low, occurring in only 5% (26/539) of all patients. The most common drug-related study events were GI-related, occurring in < 8% of patients. Elderly persons (> or = 65 years of age) were not at greater risk for adverse reactions or drug-related study events than were younger patients. Serious GI-related study events were rare (0.2%). The low level of serious GI effects was consistent with a separate study measuring gastrointestinal (GI) blood loss. Etodolac SR produced significantly less GI blood loss than naproxen in normal subjects. Because of its favorable safety profile, etodolac SR can serve as an alternative to conventional etodolac, providing the convenience of once-daily administration.

A comparison of two formulations of indomethacin ('Flexin Continus' tablets and 'Indocid' capsules) in the treatment of osteoarthritis

The efficacy and side-effect profiles of two formulations of indomethacin were compared in a multi-centre, double-blind, crossover study in 77 patients with osteoarthritis. Patients were allocated at random to receive 75 mg indomethacin per day either as 1 controlled-release tablet at night or as 1 immediate-release capsule given 3-times daily for a period of 4 weeks, after which patients were crossed over to receive the alternative treatment for a further 4 weeks. Pain scores, daily symptomatology and the requirement for escape analgesia recorded by the investigator and patient indicate that controlled-release indomethacin tablets, 75 mg given at night, were as efficacious as immediate-release indomethacin capsules, 25 mg given 3-times daily, in the treatment of osteoarthritis. The side-effect profiles of the two formulations were similar.

The effect of different indomethacin formulations in young and elderly patients: a comparative controlled clinical trial

In a double-blind, crossover trial a controlled-release multiple-units indomethacin formulation (50 mg twice daily) was compared with conventional capsules (25 mg twice daily with 50 mg in the evening) in 12 young and 18 elderly in-patients with rheumatoid arthritis. Earlier findings that younger patients preferred a slow-release formulation and the elderly a standard formulation could not be confirmed. As a whole, the duration of morning stiffness was reduced more (p = 0.02) with the controlled-release formulation than with the conventional formulation. During the treatment period (7 days), 4 patients reported side-effects from the conventional capsules, 3 from the controlled-release formulation, and 6 from both treatments; 53% of the patients preferred the controlled-release formulation, while 20% preferred the conventional capsule (p = 0.046).

Diarrhoea and constipation

Drug-induced constipation is mostly caused by changes in gut motility, whilst diarrhoea is more frequently caused by an increase in intestinal fluid secretion. In both instances the drug has to reach the enteric nervous system or the enterocyte, either via the blood or from the lumen, in sufficient concentrations to affect the mediators that regulate motility and fluid transport. Diarrhoea and constipation are frequently mentioned as side-effects of drugs, and therapeutic agents for almost all organ systems have been implicated. However, both these side-effects are usually mild or moderate, and rarely necessitate interruption of drug treatment. An exception to this rule is the antibiotic-associated colitis seen in patients treated with antibiotics such as lincomycin or clindamycin; in principle almost all antibiotics may cause this severe and potentially life-threatening complication. Other rare forms of severe, drug-induced colitis and diarrhoea result from toxic or anaphylactic reactions against gold preparations, cytostatic agents and sulphonamides. Ischaemic colitis due to vascular complications has been described in some women taking oral contraceptives, and in patients treated with vasopressin or digitalis.

Comparison of a slow-release indomethacin tablet and naproxen in osteoarthrosis

A double-blind, crossover study was performed in 21 out-patients with osteoarthrosis of the hip or knee to compare the efficacy and tolerability of a new slow-release formulation (multiple units dose preparation) of indomethacin (50 mg) with those of naproxen (250 mg). After a wash-out period of 1 week, the patients were randomized to receive 2 tablets daily of one or other preparation for 3 weeks. This was followed by another wash-out period of 1 week, whereafter the patients were crossed over to the alternative drug for another 3 weeks. Subjective assessments of pain and objective assessment of joint mobility and the use of acetylsalicylic acid as rescue analgesic were used to evaluate the efficacy of the treatment. Analysis of results from 19 patients showed that both drugs effectively alleviated pain, and there was no difference between indomethacin and naproxen in this respect. There were 2 withdrawals, 1 on naproxen due to inefficacy and 1 on indomethacin due to gastro-intestinal side-effects. Otherwise, the drugs were well tolerated and side-effects occurred to the same extent on both drugs. This study confirms the good efficacy and tolerability of the new slow-release indomethacin preparation.

Indomethacin sustained-release?

Recently, many new formulations of older drugs have been marketed as sustained-release preparations. Only some of these compounds have scientific rationale supporting their development. At least two inherent properties of a drug are desirable in considering its reformulation into a sustained-release entity. On of these properties is the demonstration of a concentration/response relationship together with a short plasma elimination half-life and inactive or uncharacterized activity of any generated metabolites. The second property is the production of transient side effects associated with dissolution and/or peak concentrations. When neither of these conditions is satisfied, then a sustained-release preparation may offer no advantages over the conventional formulation. The literature on indomethacin was examined with respect to the above conditions and it was concluded that its marketing as a sustained-release preparation is not justified and that investigations have failed to demonstrate clinical advantages of this new formulation.

Comparison of slow-release indomethacin and diflunisal in patients with arthrosis

A double-blind, crossover study was carried out in 44 patients with osteoarthrosis of the hip or knee to compare the efficacy and tolerability of treatment with a new slow-release formulation of indomethacin (50 mg) with that of diflunisal (250 mg). After a 1-week wash-out period, patients were allocated at random to receive 2 tablets daily of one or other preparation for 6 weeks before being crossed over to the alternative drug for a further 6 weeks. Aspirin was allowed as a rescue analgesic throughout the study. Subjective assessments of pain and objective assessments of joint mobility were made before the start of treatment and at the end of each period, and details were recorded of rescue analgesic usage and any side-effects. Analysis of the results from 42 patients showed that whilst both treatments helped to alleviate pain, patients' overall evaluation of efficacy at the end of the study indicated that indomethacin was slightly more effective than diflunisal and there was a significant preference for indomethacin. Both drugs were well tolerated and none of the side-effects, reported in about 15% of patients on each drug, resulted in any withdrawals.

Chronopharmacokinetic study of a prolonged release form of indomethacin

The chronopharmacokinetics of indomethacin was studied in patients with rheumatoid diseases after a single oral dose of a new prolonged-release form containing indomethacin 75 mg. The drug was given either at 8, 12 or 20 h and its plasma concentrations, as well as those of its main metabolite, O-desmethyl indomethacin, were followed using a new specific gas chromatographic assay. When given at 20 h plasma indomethacin concentrations did not exhibit a sharp peak and remained much more stable than when the drug was given at 8 or 12 h. In addition, plasma O-desmethyl indomethacin was significantly higher after administration of indomethacin at 20 h than at 8 or 12 h. It is concluded that the pharmacokinetics of the oral prolonged-release form of indomethacin exhibited chronobiological variation. The data are in accordance with clinical studies which suggest that it might be worthwhile to administer this formulation of indomethacin at 20 h.