Thanks Ankit.
As per this news article, pegs the generic market for Celebrex at $400 million.
"Lupin currently holds 14 per cent market share for Celebrex and expect $58 million sales from the drug with a 15 per cent market share"
However, off late, there are reports of adverse effects from generic Celebrex, read here. So it is debatable how easy it will be for Alembic to garner market share.