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Dosage: Selection of patients and approach to lithium therapy: The results of lithium therapy depend largely on the nature and course of the illness itself, rather than on the symptoms. The selection of patients for long-term treatment requires a clearcut diagnosis of primary affective disorder, the condition for which the stabilizing effects of lithium have been found useful. The variables that have been more consistently associated with response to lithium therapy in patients with a primary affective disorder are: the good quality of remissions with good function and no significant symptomatology during the free intervals between previous episodes of illness; low frequency of episodes, typically 1 or 2 (and not more than 3 or 4) per year; and symptomatology during the acute episodes that meet strict criteria for a primary affective disorder (DSM-III; Research Diagnosis Criteria).
Screening for lithium candidates should include at least, a medical history and physical examination with emphasis on the CNS, urinary, cardiovascular, gastrointestinal and endocrine systems and the skin. It should also include: routine 24 hour urine volume, serum creatinine, record of weight, and ECG, possibly electrolytes and TSH, and for long-term treatment, creatinine clearance and a urine concentration test. Also, consider serum calcium level before onset of treatment, after 6 months, and yearly thereafter in long-term treatment. Other examinations and tests should be used when indicated. Monitoring pms-LITHIUM CARBONATE treatment should include, for each visit, mental status, physical examination, weight, 12 hour serum lithium and a check for lithium side effects and compliance. It should also include serum creatinine every 2 months, plasma thyroid hormone and TSH every 6 to 12 months, particularly in female patients, and attention to renal and thyroid function should be maintained throughout, with tests used for baseline screening repeated as required.
The first objective of treatment is to establish an effective and safe daily dosage of lithium with the aid of standardized 12 hour serum lithium levels maintained within the therapeutic range, as high as necessary for efficacy, and with the patient as much as possible free of significant side effects. Three daily doses should be used initially, at least until the daily dosage is established. The next aim is to move to an optimal dose, which should be as low as possible, consistent with protection against relapse. During follow-up, an adjustment to lower dosages may be required to minimize adverse effects, and a change in the lithium preparation used and/or the frequency of dosing, either towards multiple doses or towards a single dose, may be necessary to handle absorption-related adverse effects or concern over possible renal toxicity. Intermittent lithium treatment in carefully selected patients has been recommended by some lithium experts, but should not be undertaken without careful planning and great caution. The cooperation of patients and relatives is required throughout.
Before deciding on the institution of long-term treatment, it is essential to establish that the patient has clearly responded to a course of stabilizing lithium therapy and that the risk of such therapy is acceptable. Maintaining a patient with a lithium non-responsive condition on long-term therapy poses an unacceptable risk. A decision with regards to long-term therapy can be made during a time-limited trial of lithium therapy with frequent reassessment of outcome. The following are among the factors to be reassessed before a decision is made: careful reconfirmation of the diagnosis of primary affective disorder; the health status of the patient; the side effects of lithium therapy experienced by the patient; and the response to treatment. Assessment of response to treatment is based strictly on firm evidence of relapse prevention during a reasonable trial period, but can be assisted by consideration of the predictors of response outlined previously. Great pains should be taken to exclude false responders and false non-responders. It should also be borne in mind that non-responders are more susceptible to the adverse effects of lithium.
Acute Mania: The therapeutic dose for the treatment of acute mania should be based primarily on the patient's clinical condition. It must be individualized for each patient according to blood concentrations and clinical response. The dosage should be adjusted to obtain serum concentrations between 0.8 and 1.2 mEq or mmol/L (in blood samples drawn before the patient has had his first lithium dose of the day).
In properly screened adult patients, with good renal function, the suggested initial daily dosage for acute mania is 900 to 1800 mg (15 to 20 mg/kg), divided into 3 doses. In view of the large variability of renal lithium excretion between individuals, it is suggested that lithium treatment be started at a dose between 600 and 900 mg/day, reaching gradually a level of 1200 to 1800 mg in 3 divided doses. Depending on the patient's clinical condition, the initial dosage should be adjusted to produce the desired serum lithium concentration. The weight of the patient should also influence the choice of the initial dose.
Elderly Patients: pms-LITHIUM CARBONATE should be used cautiously and in reduced doses in the elderly patient, usually in the range of 600 to 1200 mg/day. Serum lithium concentrations should be monitored frequently and kept below 1.0 mEq/L or mmol/L.
Maintenance Therapy: After the acute manic episode subsides, the dosage should be rapidly reduced to achieve serum concentrations between 0.6 and 1.0 mEq or mmol/L, since there is evidence at this time of a decreased tolerance to lithium. The average suggested dosage at this stage is 900 mg/day (approximately 25 mEq), divided into 3 doses, with a range usually between 500 and 1200 mg/day.
If a satisfactory response to antimanic lithium is not obtained in 14 days, consider discontinuing pms-LITHIUM CARBONATE therapy. When the manic attack is controlled, maintain lithium administration during the expected duration of the manic phase, since early withdrawal might lead to relapse. It is essential to maintain clinical supervision of the patient and monitor lithium concentrations as required during treatment (see Precautions).
Once patients are stabilized on a maintenance dose with a multiple dosing schedule, and once stable therapeutic blood levels are reached, the dosage schedule may be changed to a once daily dosage administration.
The total daily dose, when administered as a single daily dose, may be approximately 5 to 30% lower than when given in divided doses over the day.
It is essential to maintain clinical supervision of the patient and to monitor serum lithium levels both when using the divided daily dosage regimen and when transferring to the once daily administration dosage regimen.
In uncomplicated cases receiving maintenance therapy during remission, serum lithium levels should be monitored at least every two months.
Patients abnormally sensitive to lithium may exhibit toxic signs at serum levels of 1 to 1.4 mEq/L.
Elderly patients often respond to reduced dosage and may exhibit signs of toxicity at serum levels ordinarily tolerated by other patients.
NOTE: Blood samples for serum lithium determination should be drawn immediately prior to the next dose when lithium concentrations are relatively stable (i.e. 12 ± 1 hours after the previous dose of lithium). Total reliance must not be placed on serum levels alone. Adequate patient evaluation requires both clinical assessment and laboratory analysis.
Use in Children: pms-LITHIUM CARBONATE is not recommended for routine use in children under 12 years of age since information in this age group is not yet available.
