To determine the efficacy and safety of diacerhein, a potential new therapeutic agent with properties differing from those of existing nonsteroidal anti-inflammatory drugs (NSAIDs), and of a combination of diacerhein and an NSAID (tenoxicam) in the treatment of osteoarthritis (OA) of the hip.
Two hundred eighty-eight patients with painful OA of the hip were enrolled in an 8-week randomized, double-blind, placebo-controlled, 2 x 2 factorial design study. Four treatment groups were defined: 1) diacerhein placebo and tenoxicam placebo, 2) tenoxicam and diacerhein placebo, 3) diacerhein and tenoxicam placebo, and 4) diacerhein and tenoxicam. The daily dosages of diacerhein and tenoxicam were 100 mg and 20 mg, respectively.
Analyses of efficacy showed no interaction between diacerhein and tenoxicam in terms of efficacy, a clinically significant rapid (< or = 2 weeks) and persisting effect of tenoxicam during the 8 weeks of the study, and a slow-acting (6 weeks) effect of diacerhein. Moderate, transient diarrhea was the most frequent side effect observed in the diacerhein group (37%) compared with the placebo group (4%).
Both tenoxicam and diacerhein appear to be superior to placebo, and neither agent appears to significantly enhance or detract from the efficacy of the other when they are administered concomitantly. The onset of action of diacerhein appears to be delayed (> or = 4 weeks).