Ibuprofen carries little risk of causing serious gastrointestinal toxicity when taken as an OTC analgesic, a new study has shown.

Previously, the possible risks associated with lower doses of ibuprofen ( i.e. OTC doses) have not been extensively studied and this has often caused confusion in relation to the potential adverse effects which are recognised for high-dose, regular use of non-steroidal anti inflammatory drugs (NSAIDS).

Investigators at Stanford University, California, compared the frequency of serious gastrointestinal (GI) events in 5,692 patients with rheumatoid arthritis (RA) and 3,124 patients with osteoarthritis (OA) who had taken ibuprofen, aspirin or paracetamol in the previous 6 months.

In patients with RA who had not been taking other drug therapy for their arthritis, the rate of serious GI events with ibuprofen was 3.1 per 1,000 patient-years of use compared with 4.0 for aspirin and 2.6 for paracetamol. In patients with OA, the corresponding figures were 2.4 for ibuprofen, 2.9 for aspirin and 2.1 for paracetamol. The investigators described these rates as ‘low and statistically indistinguishable’. In patients taking the lowest doses of analgesics, there were ‘extremely low or even no GI event rates’.

The data revealed that when serious GI toxicity did occur in these patients it was largely attributable to known risk factors such as other drug therapy for arthritis, health status and previous occurrence of GI events. For each of the analgesics studied, the rates of GI toxicity increased with the additional use of NSAIDs and corticosteroids. The investigators were surprised to find that the rate of serious GI toxicity among patients taking both NSAIDs and corticosteroids was statistically significantly greater with paracetamol (15.0 per 1000 patient-years in patients with RA and to 12.0 in patients with OA) than with ibuprofen (6.1 and 5.4 respectively) or aspirin (8.7 and 4.7 respectively). However, the total number of patients involved was small.

This study - one of the scientifically most robust analyses of the safety of OTC analgesics ever published - reflects the doses and frequencies with which patients with RA or OA take analgesics. The investigators conclude that their findings support the relative safety of ibuprofen, aspirin and paracetamol used in this way, especially in patients not taking other drug therapy.

Notes for editors
1. The study, published in the October issue of the Journal of Rheumatology
(2003;30:2226-33, www.jrheum.com), was a prospective analysis of twelve US and Canadian databanks. The average age of the patients was 57 (RA) and 66 (OA); 75% were women; and the average disease duration was 16 (RA) and 17 (OA) years.

2. Serious GI toxicity was defined as: upper or lower GI bleeding during use of NSAIDs; symptomatic gastritis, ulcers or gastric outlet obstructions; and GI symptoms serious enough to warrant admission to hospital. All GI events reported by patients were validated by a physician or from medical records.

3. Patients were divided into four groups depending on the dose of analgesic. For ibuprofen, the groups were 100, 101 - 1100, 1101 - 2200 and >2200 mg/day; for aspirin and paracetamol, the groups were 162, 163 - 1300, 1301 - 2600 and >2600 mg/day. Lowest doses were assumed to indicate intermittent use.

4. Patient-years of use is a standard measure of the exposure of a study population to a treatment. It is calculated by multiplying the number of patients taking the treatment by the duration of their treatment (as a decimal fraction of a year).

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