Estimation of lithium dose requirement by lithium clearance, serum lithium and saliva lithium following a loading dose of lithium carbonate

How to initiate lithium therapy: a systematic review of dose estimation and level prediction methods

BACKGROUND

Throughout the past decades, several methods have been developed to achieve therapeutic lithium blood levels as quick and safe as possible. The present study will systematically review the methods developed and studied for lithium dose estimation or level prediction at the initiation of therapy.

METHODS

A systematic computerized Medline search was performed for papers published in English, French or Dutch between 1966 and April 2012 describing or studying methods for dosing lithium or predicting the lithium level on a certain dosage. References of relevant articles were screened for additional papers.

RESULTS

Of 273 unique references retrieved, 65 met the inclusion criteria. Apart from the empirical titration method, 38 predictive methods for initiating lithium were identified. These methods can be classified into two categories: the a priori predictive methods, and the test-dose predictive methods requiring the administration of a test dose of lithium prior to starting treatment.

LIMITATIONS

The methodological strength was not taken into account for a study to be included in the review.

CONCLUSIONS

The most important distinction between the empirical titration method and the predictive methods appears to be the shorter time the latter need to achieve the targeted lithium level. The vast majority of predictive methods, however, show inconsistent or poor results or have not been replicated since their initial description. The empirical titration method, although not extensively studied, appears to be a time-honored method that can be recommended for use in daily clinical practice.

A pilot study of rapid lithium administration in the treatment of acute mania

OBJECTIVES

The use of rapid lithium dosage administration, a strategy that could lead to rapid improvement in mania, has been largely unexamined. In this open-label, pilot, acute-treatment study, we sought to determine the safety and tolerability of lithium administered at 20 mg/ kg/day. A secondary aim was to provide preliminary data regarding the efficacy of this strategy in ameliorating manic, depressive, and psychotic symptoms.

METHODS

Fifteen patients hospitalized with DSM-IV bipolar disorder, manic or mixed, and who provided written informed consent, received lithium 20 mg/kg/day for up to 10 days. Patients were evaluated for adverse effects daily. Lithium levels were obtained on days 2, 3, 4, 5, 7, and 10 or at study termination. Electrocardiograms (EKGs) were performed at baseline and on days 1-5, 7, and 10 or at study termination. Symptomatic improvement was assessed daily using the Young Mania Rating Scale, 24-item Hamilton Depression Rating Scale, and the Scale for Assessment of Positive Symptoms (SAPS).

RESULTS

Five of the 15 patients completed the 10-day study period. Two patients dropped out due to adverse events. Seven patients did not complete the inpatient trial because of improvement sufficient to allow hospital discharge. All patients achieved serum lithium concentrations > or =0.6 mEq/L after 1 day of treatment; the mean + SD concentration on day 5 was 1.1 (+/- 0.1) mEq/L on day 5. There were significant reductions from baseline to endpoint on all rating scales, except the SAPS bizarre behavior subscale.

CONCLUSIONS

These pilot data suggest that lithium 20 mg/kg/day was well tolerated and that this strategy may produce rapid improvement in affective and psychotic symptoms. These impressions require confirmation in double-blind, randomized trials.

Pharmacologic loading in the treatment of acute mania

The rapid and safe reduction of manic symptoms is an important initial goal of the pharmacologic treatment of acute mania. The pharmacokinetics and studies of pharmacologic loading of lithium, valproate, and carbamazepine were reviewed. In addition, the feasibility of administering other agents with potential efficacy in mania, e.g., atypical antipsychotics and new anticonvulsants, was discussed. Further double-blind, controlled studies with adequate sample sizes comparing loading strategies with more gradual titration schedules of candidate antimanic agents are needed.

A review of lithium dosing methods

Lithium's narrow therapeutic range, concentration-effect relationship, and large differences in interindividual disposition make it an attractive candidate for predictive dosing methods. Lithium disposition is influenced by a number of factors, including patient characteristics, renal function, and concomitant drug therapies. These factors are accounted for, in varied degrees, in the different dosing methods available. One a priori method takes many of these factors into account and appears to have better reliability than others that ignore nonrenal influences on lithium disposition. The lack of data on pharmacokinetic values in different populations limits the usefulness of many of the single-point methods. Better data on the disposition of lithium in differing populations would greatly enhance the utility of both the a priori and single-point methods. Several multipoint methods, which estimate an individual's pharmacokinetic values, have also been described. These appear to be the most reliable, although they are time consuming and may delay the initiation of therapy. A well-designed Bayesian approach to the dosing of lithium, although not currently available, would be the most useful.

Lithium: long-term effects on the kidney. IV. Renal lithium clearance

Renal lithium clearance was investigated in 44 patients treated with lithium for an average of 8 years as part of a functional-morphological follow-up study including a kidney biopsy. The average renal lithium clearance was 0.36 ml/s (= 21.6 ml/min). A significant correlation with age, sex and glomerular filtration rate was seen, whereas no significant relationship with urine volume, lithium treatment regimen and histopathological biopsy variables was found. The results were compared with the same renal functional tests obtained from a control group consisting of 26 patients with affective disorders never treated with lithium. The control group had a lower urine output, but no significant difference in lithium clearance was observed. In conclusion, renal lithium clearance is a specific investigation, which may provide valuable baseline information on glomerulo-tubular function in patients before and during prophylactic lithium treatment.