Rotahaler and inhaler are two different forms of delivery. One is powder other is gaseous form. Either is good if taken properly. Next issue is medicines. Duolin is an emergency medicine which should be used when maximum needed. But a different kind of medicine is given in asthma which is a controller and controls the symptoms and prevents attacks. This medicine has to be taken daily twice even if you don't have any problem. This is to keep your inner lungs healthy. If you are healthy you won't need duolin. If you use least duolin means your asthma is controlled. This controller can come in various companies, but may be I can spell some. Seroflo foracort budamate esiflo. Consult chest physician for further information