Therapeutic Drugs Monitoring - Lithium

Lithium, administered as Lithium carbonate, is used for the treatment of the manic phase of affective disorders, mania, and manic-depressive illness. It acts by enhancing reuptake of neurotransmitters, thereby reducing their concentration in the neuronal junction. This produces a sedating effect on the central nervous system. It is completely absorbed by the gastro-intestinal tract and peak serum levels occur 2 to 4 hours after an oral dose. The half-life in serum is 48 to 72 hours and is cleared through the kidneys. Reduced renal function can prolong clearance time.

Early symptoms of intoxification include apathy, sluggishness, drowsiness, lethargy, speech difficulties, irregular tremors, myoclonic twitchings, muscle weakness and ataxia. Levels higher than 1.5 mmol/l (12 hrs after a dose) indicate a significant risk of intoxification. Serum lithium concentrations are carried out essentially to ensure compliance and to avoid toxicity.