Lithium carbonate

NARROW THERAPEUTIC WINDOW — the dose must be titrated and adjusted on the basis of regular serum concentration monitoring, and therapy should not be initiated unless adequate facilities for routine plasma-level monitoring are available. Blood samples for plasma lithium must be taken 12 hours after the last dose. Monitoring: weekly on initiation until stabilisation, then weekly for one month, then monthly; more often on dose alteration, intercurrent illness, signs of toxicity, relapse, significant change in sodium or fluid intake, or with drugs affecting renal lithium clearance (diuretics, NSAIDs). If the preparation is changed, monitor weekly until restabilised (bioavailability varies between formulations). ACUTE MANIA: treatment should be initiated in hospital; the target level may alternatively be reached by calculating the initial dose from a lithium clearance test, but weekly levels are still advised for the first three weeks. The precise initial dose should reflect the patient's age and weight — younger patients often need a higher than average dose and older patients a lower dose. HYPOMANIA: most of the above applies, but a patient who is not too ill may start as an outpatient provided regular monitoring is available and assays are initiated within one week. PROPHYLAXIS OF RECURRENT AFFECTIVE DISORDERS (unipolar mania, unipolar depression, bipolar manic-depressive illness): 300-400 mg daily for the first seven days, then adjust to keep the plasma lithium level within 0.4-0.8 mmol/l. AGGRESSIVE AND SELF-MUTILATING BEHAVIOUR: dosage is at the lower end of the manic-depressive illness range. ELDERLY: start with a low dose; elderly patients often need lower doses to achieve therapeutic levels, and 12-hour levels should be kept in the range 0.4-0.7 mmol/l as toxic symptoms are likely above 1.0 mmol/l and may occur at lower concentrations than in the general population. WITHDRAWAL: if lithium is to be discontinued for other reasons, particularly at high doses, reduce gradually over a suitable period (e.g. 2 weeks) to prevent relapse. PAEDIATRIC: the eMC SPC for this 250 mg film-coated tablet states it should not be used in children — verify against a children's formulary if lithium is being considered in an under-18. NOTE: several numeric ranges and comparator symbols were damaged in the source text extraction (e.g. '0.4¬0.8', '0.40.7') — verify every threshold against the current SPC before use.