Antiemetic efficacy of high-dose dexamethasone: randomized, double-blind, crossover study with a combination of dexamethasone, metoclopramide and diphenhydramine.

A double-blind, randomized, crossover study was conducted to compare the efficacy and safety of high-dose dexamethasone (Protocol D) with a combination of dexamethasone, metoclopramide and diphenhydramine (Protocol DMD) in the management of chemotherapy-induced nausea and vomiting in cancer patients. All entered patients had received no prior chemotherapy. During the study chemotherapy was administered on an inpatient basis. The majority of patients (94%) were treated with cytotoxic drugs of significant emetogenic activity and 40% of the study group received cis-platin-containing combinations. Of the 60 evaluable patients, complete antinausea and antivomiting effects of D were observed in 30 (50%) and 34 (57%), respectively and of DMD in 17 (28%) and 26 patients (43%) respectively. The difference was not statistically significant (P = 0.09 and 0.24, respectively). Lack of significant difference between the two regimens was demonstrated irrespective of the administered cytotoxic drugs. The DMD protocol caused more adverse reactions than D. While 27 patients (45%) experienced no side effects from D, only 14 (24%) remained free of complications due to DMD (P = 0.001). Furthermore, DMD produced more sedation, insomnia, headache, diaphoresis, dizziness and diarrhoea than the D regimen. In addition it gave rise to more adverse effects on appetite and activity. Upon direct questioning, 37 patients (62%) expressed a preference for D, 14 (23%) preferred DMD and 9 (15%) found no difference between the two regimens. We conclude that, while the short DMD protocol has an antiemetic activity equivalent in its effectiveness to D, its associated adverse reactions would minimize its usefulness. Therefore, further investigations should be conducted to find a safer and more potent combination of antiemetics suitable for therapy in an outpatient setting.