A few blisters of "Seroquel XL" (quetiapine, an antipsychotic, and a fairly reasonable dose of it, too) have been found in packs of "Nurofen Plus" (ibuprofen and codeine, an "over the counter" i.e. purchasable painkiller).
Sabotage, I wonder? Especially as they're made by different companies.
Edit: Aha, there's some stuff on the Beeb