I know migraine can be affected by nitrates/nitrites and sulphites, but what about phosphates?

Tomorrow i am having a big steroid injection of Dexamethasone phosphate (to help mature my two babies lungs before birth), first i thought this corticosteroid might actually help my MAV but if it’s got phosphate in the name could it make me worse? Does anyone know anything about this drug or about phosphates and migraine?