5-Fluoromethylornithine dihydrochloride (5-FMOrn dihydrochloride) is a selective inhibitor of L-Ornithine:2-oxoacid aminotransferase (OAT) and a specific inactivator of OAT, which can be used to study metabolic diseases and neurological diseases.

Incubation for 1 h of L-ornithine carbamoyltransferase, ODC and GABA-T preparations with up to 10 mM 5-Fluoromethylornithine and subsequent determination of the residual enzyme activity demonstrated that none of these enzymes was inactivated. 5-Fluoromethylornithine is a poor substrate of ODC; at 10 mM 5-Fluoromethylornithine, 0.04 nmol of 1-fluoromethylputrescine was formed/h per mg of protein. [1]

After intraperitoneal administration of 10 mg of 5-Fluoromethylornithine /kg, there is a rapid decrease of OAT activity in all organs, to a basal value. The time-dependence of the effect of 5-Fluoromethylornithine in brain. Minimum activity was usually observed between 2 and 24 h after 5-Fluoromethylornithine administration, thereafter OAT activity recovered gradually. [1]