Actrapid is a fast-acting human soluble insulin. This means that it will start to lower your blood sugar about half an hour after you take it. The effect will last for approximately 6-8 hours. When it enters the body, it works in the same way as natural insulin and increases overall ability for the body to uptake glucose. It comes in a 10 ml vial that you use to fill an insulin syringe. Actrapid insulin pens with replaceable 3ml cartridges available upon request.