Why must levobupivacaine 7.5 mg/ml solution for injection/infusion (Martindale Pharma, an Ethypharm Group Company product) not be diluted or co-administered with sodium bicarbonate injections?

Levobupivacaine 7.5 mg/ml solution for injection/infusion (Martindale Pharma, an Ethypharm Group Company product) must not be diluted or co-administered with sodium bicarbonate injections because levobupivacaine may precipitate in alkaline solutions, and mixing with other medicines is prohibited except those specified in section 6.6.