Colchicine has been shown to cause reversible malabsorption of vitamin B12 by altering the function of the ileal mucosa. Colchicine can reduce the absorption of fats, sodium, potassium, nitrogen, xylose, and other actively transported sugars. This can lead to decreased serum cholesterol and carotene levels.
Colchicine is inhibited by acidifying agents but enhanced by alkalizing agents.
Colchicine may increase sensitivity to central nervous system depressants and enhance responses to sympathetic-like substances.
Colchicine can cause false-positive results when testing for RBC or hemoglobin in the urine.
Colchicine can react with cyclosporin, resulting in an increased risk of kidney toxicity and increased plasma levels of cyclosporin.
Colchicine has been reported to interfere with the determination of 17-hydroxycorticoids in urine using the Reddy, Jenkins, and Thorn procedure. Concomitant use with clarithromycin can lead to colchicine poisoning. Colchicine is a CYP3A transmetabolite and P-glycoprotein (Pgp) flow transporter. Clarithromycin and other macrolides inhibit CYP3A and Pgp. When clarithromycin and colchicine are used concomitantly, inhibition of Pgp and/or CYP3A by clarithromycin can lead to an overdose of colchicine. Patients should be monitored for clinical symptoms of colchicine poisoning.
Concomitant use with erythromycin can also lead to colchicine poisoning.