Effects of caffeine as an adjuvant to morphine in advanced cancer patients: A randomized, double-blind, placebo-controlled, crossover study

Psychomotor abnormalities are one of the complications of opioid therapy in advanced cancer patients. Caffeine has potential properties to counteract the central effects of morphine. Twelve patients receiving stable doses of slow release morphine with adequate pain relief were scheduled for this dou ble-blind placebo-controlled crossover trial. The treatment consisted of an intravenous dose of 1/6 of the daily morphine dose, using an intravenous/o ral conversion ratio of 1:3. The dose calculated was administered in 5 minu tes. Patients were randomly divided to recieved in a double-blind manner an infusion of 200 mg of caffeine or saline solution intravenously over one h our A crossover took place after 2-3 days. Patients were assessed immediate ly before the infusion and once at the end (one hour after). Each assessmen t included pain, nausea, confusion, and drowsiness intensity. Psychomotor t ests, including tapping speed with 10-30 seconds trials, arithmetic tests, memory for digits, and visual memory were also confirmed. Caffeine infusion Induced a significant decrease in pain intensity (from 25.3 to 16.3, p = 0 .003), but this was no different from the placebo. Caffeine increased both tapping speed tests (p = 0.041 and 0.010, respectively) in comparison with placebo treatment. No other significant differences were found in the other -parameters examined. Caffeine showed a partial effect on the cognitive per formance of advanced cancer patients on chronic morphine treatment who rece ived a bolus of intravenous morphine. Further studies are necessary to eval uate whether higher doses of caffeine may be more effective and to establis h the role of tolerance to caffeine in this group of patients.