Tuesday, June 19, 2012

Will Celebrex (Celecoxib) post patent expiry eat into the share of other NSAIDS

Celebrex is a COX-2 inhibitor, but unlike the ones discontinued (Vioxx)  it has a proven CV safety profile. The potential market share of Celebrex is currently restricted due to availability of therapeutic substitutes (Ibuprofen, Naproxen, Meloxicam), that are available as generics. Ibuprofen and Naproxen lead the pain management market for Arthritis. Ibuprofen has close to 40% market share, followed by Naproxen with 20% market share. Celebrex takes about 10% market share. Post patent expiry (2014), Celebrex  should eat away into share of other NSAIDS.

Existing Widely used painkillers are associated with GI safety issues
The existing pain-killers (ibuprofen, diclofenac) which are widely used, are associated with Gastro Intestinal  safety issues. Up to 30% of patients taking traditional NSAIDs develop persistent GI symptoms, and more than 10% of all patients discontinue treatment. An estimated 33 million people take traditional NSAIDs regularly

Post Patent Expiry, we will see a change in the pharmacoeconomic profile of Celebrex which should help therapeutic substitution
The existing generic options on the market are about 10 times cheaper than Celebrex, while based on clinical evidence, Celebrex  does not appear to be any more or any less effective than other non-steroidal anti-inflammatory drugs (NSAIDs) in treating the symptoms of osteoarthritis (OA) or rheumatoid arthritis (RA). The potential benefit of a cyclooxygenase-2 (COX-2) inhibitor such as celecoxib is primarily due to the lack of inhibition of cyclooxygenase-1 (COX-1) at therapeutic doses. Lack of COX-1 inhibition is mechanistically related to a potential decrease in the risk of GI adverse events (ulceration, bleeding, and perforation). Celecoxib lacks the platelet effects associated with other NSAIDs. Celecoxib does not appear to differ from other NSAIDs in terms of renal adverse effects or use during pregnancy.

Currently NSAIDS are combined with antiacid drugs to control the GI side effects, but once celebrex is available at the same price as other pain killers, we would see Celebrex as a preferred option because it would provide the convenience of taking a single drug.

At the current price, pharmacoeconomic benefit of reduced GI hospitalization does not justify the additional costs, but post patent expiry it would
For patients with rheumatoid arthritis (RA), the annual rate of GI hospitalizations is about 1.46% in patients taking NSAIDs compared to 0.27% in patients not taking NSAIDs. Number-needed-to-harm (NNH) = 84. For patients with osteoarthritis (OA), the annual rate of GI hospitalizations is about 0.73% in patients taking NSAIDs compared to 0.29% in patients not taking NSAIDs. NNH = 227.

If the assumption is made that the rate of GI adverse events in patients receiving celecoxib is equal to the rate in patients not receiving NSAIDs, 84 RA patients or 227 OA patients (or an even greater number of patients in the general patient population) would have to be treated with celecoxib for 1 year in order to avert 1 GI hospitalization. Treating 84 RA patients with celecoxib would increase annual drug costs by approximately $41,403 compared to treatment with conventional NSAIDs. Treating 227 OA patients with celecoxib would increase annual drug costs by approximately $111,888 compared to treatment with conventional NSAIDs.

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