The present invention relates to a three-chambered autoinjector as well as to the methods of administering medicaments to a human using the three-chambered autoinjector. In certain embodiments, the autoinjector includes a first medicament in liquid form, a second medicament preferably in solid form, and a liquid composition for diluting the second medicament, and utilizes a three-chambered design so as to administer the first medicament and a solution comprising the second medicament and the liquid composition at different injection depths into the body of a human. In an alternative embodiment an autoinjector is provided that delivers medicaments at the same injection depth.