Objective. This pilot study clinically tests whether a conversion factor of 2 to 1 is appropriate when changing from oral to parenteral morphine administration in the treatment of cancer-related nociceptive pain and calculates the size of an adequately powered future study. Methods. Eleven outpatients with incurable cancer and well-controlled nociceptive pain were randomly assigned to either intravenous or subcutaneous morphine using half the previous oral 24-hour dose. Each group crossed over after the first three-day period. Serum concentrations of morphine and its metabolites were monitored as well as intensity of pain. Results. Oral to subcutaneous and oral to intravenous quotas of morphine concentrations were approximately 0.9. Subcutaneous to intravenous morphine quotas were 1. Conclusions. The conversion factor of 2 to 1 seems to be a reasonable average but with an obvious need for individual adjustments. Concurrent medications and substantially higher doses of morphine could potentially affect the appropriate conversion factor. An adequately powered study to validate these findings would need at least 121 patients.

Ketamine with adrenaline was used as a local anesthetic for the removal of naevi, dermatofibromas, and verrucae in a double-blind study. 1 Laser surgery was used in 10 and excision using a knife in 22 cases. The ketamine concentration employed varied between 12.5 and 20.0 mg/ml. The adrenaline concentration used was 10 microg/ml. The total doses of ketamine used per patient ranged from 12.5 to 30 mg. Anesthesia as tested using the pin prick, was obtained within 1 to 3 minutes after injection and lasted for up to 11 minutes. In all patients, the injection of ketamine caused some smarting that lasted for a few to 15 seconds. Erythema always was observed in the injection area and this observation broke the double-blind code. Extrapyramidal side-effects (light-headedness and dizziness) were reported by 18 (56.2%) of our patients. Conclusion: The use of ketamine as a local anesthetic is similar to the use of lidocaine even when the doses used are small. The only drawbacks of ketamine are its short duration and the high incidence of extrapyramidal sideeffects.