RT Journal Article
SR Electronic
T1 Stability Studies of 5-Fluorocytosine in Aqueous Solutions
JF PDA Journal of Pharmaceutical Science and Technology
JO PDA J Pharm Sci Technol
FD Parenteral Drug Association (PDA)
SP 200
OP 204
VO 39
IS 5
A1 L. Biondi
A1 J. G. Nairn
YR 1985
UL http://journal.pda.org/content/39/5/200.abstract
AB The hydrolysis kinetics of 5-fluorocytosine was studied at pH 1-12, at 80°, 100°, and 121°C. The hydrolysis takes place by water attack on the protonated, neutral, and anionic forms of the drug, furthermore it is subject to catalytic hydrolysis by buffers in solution. The hydrolysis rates follow first-order kinetics. The pH profile indicates that 5-fluorocytosine has maximum stability near pH 6. In acid solution the drug deaminates to 5-fluorouracil, the final product. In neutral and basic solutions deamination takes place and nonchromophoric products are formed. The Arrhenius activation energy was found to be 25.4 Kcal/mol at pH 6.4 and the time required for 10% loss (t0.9) was estimated from the Arrhenius parameter (33 years at 25 °C).