What happened to the prescribing of other COX-2 inhibitors, paracetamol and non-steroidal anti-inflammatory drugs when rofecoxib was withdrawn in Australia?

OBJECTIVES

To analyse how the prescribing of cyclooxygenase-2 (COX-2) inhibitors, non-selective non-steroidal anti-inflammatory drugs (ns-NSAIDs) and paracetamol (acetaminophen) changed when rofecoxib was withdrawn in 2004.

METHOD

COX-2 inhibitors, paracetamol and ns-NSAID's use was measured using dispensing data for concession beneficiaries subsidized by the Australian Pharmaceutical Benefit Scheme (PBS) for the period of 1997-2005. Data were downloaded from the Medicare Australia website and converted, according to the World Health Organization (WHO) Anatomical Therapeutic Chemical (ATC)/Defined Daily Dose (DDD) (2005), to DDD/1000 concession beneficiaries/day.

RESULTS

In the period 2000-2004, the use of COX-2 inhibitors was progressively increased. Overall NSAID's use changed from approximately 80 to 105 DDD/1000 concession beneficiaries/day while a decrease of ns-NSAIDs from about 70 to 40 DDD/1000 concession beneficiaries/day was observed. Following rofecoxib withdrawal, the overall NSAIDs use declined. In 2005, celecoxib prescription declined (23%) while prescription of meloxicam increased by 62%. Use of paracetamol was steady over the period 1997-2004 (around 40 DDD/1000 concession beneficiaries/day). In April 2005, a slight increase in paracetamol use was observed.

CONCLUSION

Our analysis showed that COX-2 inhibitors prescribing markedly influenced the overall NSAIDs prescribing in Australia. When COX-2 inhibitors were introduced their uptake was rapid and extensive. Following rofecoxib withdrawal, the total overall dispensing of NSAIDs returned to a similar value as before COX-2 inhibitors' introduction. The decrease was due both to rofecoxib withdrawal and to a reduction in celecoxib prescribing. However, meloxicam use increased. Paracetamol prescribing was steady, between 1997 and 2005 and was not affected when the COX-2 inhibitors were introduced on to the market and after rofecoxib withdrawal, rather than increasing as might have been anticipated after rofecoxib withdrawal.