Chlorpheniramine inhibits the ornithine decarboxylase induction of Ehrlich carcinoma growing in vivo.

The antihistaminic (+/-)-chlorpheniramine significantly reduced the progression of Ehrlich carcinoma when it was administered at 0.5 mg/mouse/day from the third day on, after tumour inoculation. The ODC activity of tumour cells was diminished by 70% on day 7 after tumour transplantation, when maximum ODC activity is detected in non-treated tumour growing 'in vivo'. Northern blot analyses indicated that the inhibitory effect of this 1,4-diamine takes place at a post-transcriptional level. Results obtained from serum-free cultured cells indicated that chlorpheniramine inhibits the ODC synthesis rate.