Benoxaprofen: a clinical trial with an unusual design.

Benoxaprofen is a new nonsteroidal analgesic anti-inflammatory drug with a long half-life. Preliminary studies showed that steady-state blood levels could be achieved within 24 hours of treatment using a dose of 300 mg on the first day followed by 100 mg twice daily. A double-blind cross-over trial showed that benoxaprofen was effective and well tolerated in rheumatoid arthritis. Its analgesic effect was not apparent until the sixth day of treatment. An unusual trial design was used with treatment periods of unequal duration. This design has the advantage of allowing a new drug to be given for long enough to determine the time course of its action, while sparing patients prolonged treatment with placebo.