Effects of acute and short-time antibiotic treatment on renal lithium elimination and serum lithium levels in the rat.

Abstract

Male Wistar rats received a single stomach load (10 ml/kg) of a 150 mmol LiCl solution, either alone or together with tetracycline (33.5 mg/10 ml), ampicillin (33.5 mg/10 ml), or metronidazole (15 mg/10 ml). Urine was collected 1-5 hours after administration and blood samples were drawn after 1, 6, and 24 hours. All antibiotics caused a reduction in urinary lithium excretion but did not affect renal lithium clearance. Serum lithium levels were reduced by tetracycline and metronidazole 6 hours after administration but increased after 24 hours. Additional experiments including frequent mapping of serum lithium levels confirmed these findings. Tetracycline, also reduced renal sodium clearance and increased distal sodium reabsorption. Short-term daily treatment during one week with tetracycline or metronidazole showed that these initial changes were only transient, since after treatment for one week no differences could be observed between antibiotic-treated rats and control rats. The results indicate that antibiotics may cause a delay but no decrease of the gastrointestinal absorption of lithium and that they do not affect renal lithium clearance. Signs of lithium intoxication during combined use of lithium and antibiotics are therefore probably not caused by a renal interaction mechanism affecting the renal lithium clearance.