Lithium dosages

Weller, E.B., Weller, R.A. and Fristad, M.A. (1986) Lithium dosage guide for prepubertal children a preliminary report. / Am Acad Child Psychiatry 25 92-95. 

An increased lithium dosage requirement in a hyperglycemic 40-year-old woman was attributed to the osmotic diuretic effect of glycosuria, increasing lithium excretion (682). 

A 65-year-old woman taking lithium, levomeproma-zine, and phenobarbital developed a Creutzfeldt-Jakob-like syndrome after she had mistakenly increased her lithium dosage (162). 

A 26-year-old woman with bipolar I disorder took lithium and valproate, and sometimes additional risperidone and lamotrigine. Both risperidone and lamo-trigine produced dermatological adverse effects. Her serum lithium concentration was 0.82 mmol/1. Topiramate 75 mg/day was added. A week later, she continued to show a mixed state with mostly manic features and a raised lithium concentration of 1.24 mmol/1. The lithium concentration continued to increase over the next 4 days to 1.97 mmol/1 even though the lithium dosage was reduced from 900 to 750 mg/day. Lithium was withdrawn and the lithium concentration fell. Lithium was then restarted at half the admission dose to achieve a blood concentration of 0.67 mmol/1. Subsequent increases in the dose of topiramate resulted in further increases in the lithium concentration. 

A 30-year-old man required a reduction in lithium dosage from 1500 to 900 mg/day to maintain his serum lithium concentration in the target range shortly after he started to take nifedipine 60 mg/day (645). 

Oyewumi LK, McKnight M, Cernovsky ZZ. Lithium dosage and leukocyte counts in psychiatric patients. J Psychiatry Neurosci 1999 24(3) 215-21. 

Extensive retrospective and prospective studies have confirmed the value of regulating lithium dosage to maintain plasma concentrations within narrow and well-defined limits. Relapses are common at high plasma concentrations. 

A woman taking lithium carbonate developed signs of lithium toxicity (ataxia, dysarthria, tremor, confusion) within 2 to 3 weeks of starting to take enalapril 20 mg daily. After 5 weeks her plasma-lithium levels had risen from 0.88 to 3.3 mmol/L, and moderate renal impairment was noted. No toxicity occurred when the enalapril was later replaced by nifedipine. Lithium toxicity following the use of enalapril, and associated in some cases with a decrease in renal function, has been seen in another 5 patients, " and a reduced lithium dosage was found adequate in another patient. Enalapril 5 mg daily for 9 days had no effect on the mean serum-lithium levels of 9 healthy male subjects. However, one subject had a 31% increase in lithium levels. "... 

If any ACE inhibitor is added to established lithium treatment, monitor well for symptoms of lithium toxicity (see Lithium , (p. 1111)) and consider measuring lithium levels more frequently. Be alert for the need to reduce the lithium dosage (possibly by between one-third to one-half) The development of the interaction may be delayed, so monitoring lithium levels every week or every two weeks" for several weeks has been advised. 

In an apparently isolated case, a 49-year-old woman is reported to have developed nausea and vomiting associated with a rise in lithium levels following the addition of oxyphenbutazone suppositories 500 mg daily. She responded well to a reduction in the lithium dosage. ... 

Lithium levels increased. Two patients developed increased serum-lithium levels apparently due to the use of sulindac. In one case the lithium levels rose from 1 to 2 mmol/L after 19 days of treatment with sulindac 150 mg twice daily, and symptoms of toxicity were seen. The levels fell to 0.8 mmol/L within 5 days of stopping the sulindac. The other patient had a rise from 0.9 to 1.7 mmol/L within a week of adding sulindac 150 mg twice daily. The sulindac was continued and the lithium dosage was reduced from 1.8 to 1.5 g daily. The serum-lithium levels fell and were 1.2 mmol/L at 37 days and 1 mmol/L at 70 days. No symptoms of lithium toxicity occurred. ... 

The ingestion of marked amounts of sodium can prevent the establishment or maintenance of adequate serum-lithium levels. Conversely, dietary salt restriction can cause serum-lithium levels to rise to toxic concentrations if the lithium dosage is not reduced appropriately. 

Watch patients taking lithium for signs of toxicity when hyponatremia is present. This toxicity can occur even if the lithium dosage has been consistent because hyponatremia causes an increase in lithium retenhon. 

---