Infusion of drugs

A method of treating a patient by means of an at least partly implantable system for injecting a substance into the patient's body, wherein the system comprises:

• an infusion device for injecting the substance into a part of the body of the patient, the infusion device being adapted for implantation inside the patient's body,
• at least one reservoir comprising at least one compartment which accommodates and preserves or is adapted to accommodate and preserve the substance to be injected, the reservoir being adapted for implantation inside the patient's body in fluid connection with the infusion device to supply to the infusion device the substance to be injected into the patient's body, and
• an active cooling device adapted for implantation inside the patient's body and adapted to cool the reservoir and thereby keep the substance within said at least one compartment of the reservoir at a temperature below 37° C.,
• the method comprising the step of injecting—by means of the system—the substance into the patient's body in predetermined amounts.