I want to know flow rates of drug delivery systems. for example, insulin delivery needs very low flow rate. I am trying to know the minimal flow rate for every microinjection.
it depends very much on the application. A diabetic 80 kg human needs about 80 IE Insulin per day as basal rate. Insulin is available in concentration up to 500 IE/ml. That would mean a delivery rate of 0,16ml/day or 0,007ml/hour or 0,1µl/min. But you can play with the reservoir and use Insulin solutions less concentrated.
As Peter correctly said it depends on route of administration (oral, topical, parenteral, ...), type of drug, its physicochemical characteristics, type of your carrier system, (drug delivery protocol), etc. Need more clarification to get accurate answer to your question.