Objectives: To formulate an allopurinol suspension; study the chemical and physical stability of the formulation and compare the efficacy and adverse drug reactions of a 5 mg/mL allopurinol mouthwash with a placebo in the prevention of 5-fluorouracil (5-FU)-induced oral mucositis. 

Materials and Methods: First, allopurinol suspensions were extemporaneously formulated. A HPLC method was used and subsequently validated to determine the content and indicate the stability of allopurinol. The stability of this formulation was studied for a month by measuring the chemical and physical properties. Next, a randomized controlled trial was conducted in the patients receiving 5-FU. The mouthwash was administered immediately after receiving 5-FU and after 1, 2, and 3 hours by swilling around their mouth. 

Results: The analysis method was found to have specificity, linearity (r2 = 0.9999), accuracy (%recovery = 99.3-100.9%) and precision (%RSD = 0.27-0.70%). The allopurinol suspension was chemically and physically stable at the ambient temperature and 45oC for at least one month and the percentage of active content was at least 97.7%. There were 66 patients randomized to receive allopurinol mouthwash or the placebo. The evaluation did not show any statistically significant difference between allopurinol mouthwash and the placebo in the prevention of 5-FU-induced oral mucositist (p = 0.55). Adverse drug reactions reported were nausea and a burning sensation. There was no significant difference in adverse drug reactions between allopurinol mouthwash and the placebo (p = 0.41).

Conclusions: The extemporaneous preparation of the allopurinol suspension was chemically and physically stable. This study has demonstrated that 5 mg/mL allopurinol mouthwash has no effect on the prevention 5-FU-induced oral mucositis when compared with the placebo. The occurrence of adverse drug reaction was not statistically different between allopurinol mouthwash and the placebo.