Injectable rhymes with:
collectible, delectable, detectable, electable, respectable, uncollectable, undetectable, unelectable, collectible, deductible, delectable, destructable, detectable, electable, ineluctible, intractable, predictable, respectable, retractable, tractable, tractebel, uncollectable, undetectable, unelectable, unpredictable
Injectable sounds like:
inequitable, inexhaustible, insatiable, insightful