[The "pain pen", a semiautomatic morphine injection system for subcutaneous self-administration. Technique and first results.].

Subcutaneous self-administration of morphine with a "pain pen", a semiautomatic mechanical injection system about the size of a penholder, was tested in nine patients with severe chronic pain of malignant origin. During a period of treatment of 12-100 days (on an outpatient basis in three patients) side-effects of subcutaneous morphine could only be observed during a short-lasting initial period of adaptation. The average daily dosage of morphine was between 11.3+/-7.2 mg (lowest daily demand) and 20.7+/-10.5 mg (highest daily demand). Pain scaling (NSR 101) demonstrated a significant pain reduction from 80+/-19.3 to values between 5.5+/-8.3 (lowest score) and 39.4+/-14.2 (highest score during subcutaneous therapy). There were no hygienic problems, and the patients learned the technique of self-injection within a few days. This system may be especially suitable for patients with gastrointestinal incompatibility of oral opiate preparations, e.g. patients with multiple drug intake.