Which preservatives in the Rosemont Pharmaceuticals Limited orphenadrine hydrochloride 50mg/5ml oral solution product may cause delayed allergic reactions?

Methyl hydroxybenzoate (E218), 6.0mg per 5ml, and propyl hydroxybenzoate (E216), 1.5mg per 5ml, in the Rosemont Pharmaceuticals Limited orphenadrine hydrochloride 50mg/5ml oral solution product may cause allergic reactions that are possibly delayed.