An apparatus and method for a controlled injection of a drug into a selected tissue of a subject by a practitioner, uses a drive unit for supplying the drug and a handpiece to be held and guided by the practitioner, connected to the drive unit for receiving the drug. The handpiece holds an injection needle to be inserted into the selected tissue by the practitioner for passing the drug to the selected tissue at an instantaneous and absolute pressure that varies as a function of the type of tissue and the placement of the needle. A pressure sensor senses this instantaneous pressure and a feedback mechanism supplies a perceptible audible, visual or other signal to the practitioner that indicates when the instantaneous pressure has reached a minimum desired pressure, the practitioner thus being informed that the correct placement and dosage has been attained.
