On the basis of what was previously described, the mutual effects recognised at molecular level between LABAs and ICSs, can be summarised as follows:

These interacting mechanisms represent a possible molecular and receptor basis for additive/synergistic interaction between the two classes of drugs in the treatment of asthma and COPD.

It is still uncertain whether adding a LABA to an ICS results in an additive effect, since both classes have effects on a common mechanism, or whether there is true synergy. In some studies it is apparent that while the LABA may have little effect on the inflammatory process alone, there is an enhancement of the corticosteroid effect when both a LABA and an ICS are administered, suggesting that there is true synergy. This type of interaction is likely to be dependent on the cell type, the response measured and the concentrations of each drug. Whether it translates into clinical synergy has not yet been clearly established. However, even an additive interaction is likely to be clinically beneficial if the same control can be achieved with lower doses of each drug.⁷