Lithium Carbonate Extended-Release Tablets USP, contain lithium carbonate USP, a white, crystalline powder with molecular formula Li 2CO 3 and molecular weight 73.89 g/mol. Lithium is an element of the alkali‑metal group with atomic number 3, atomic weight 6.94 and an emission line at 671 nm on the flame photometer.
Lithium Carbonate Extended-Release Tablets USP
Each off-white to pale yellow, circular, beveled edged, biconvex uncoated tablets with ‘224’ debossed on one side, ‘G’ and a break line debossed on the other side, contains lithium carbonate, 450 mg. Inactive ingredients consist of ferric oxide yellow, hypromellose, magnesium stearate, microcrystalline cellulose, sodium alginate, sodium starch glycolate and talc. Product meets USP Dissolution Test 2.
Lithium Carbonate Extended-Release Tablets USP, 450 mg are designed to release a portion of the dose initially and the remainder gradually; the release pattern of the controlled release tablets reduces the variability in lithium blood levels seen with the immediate release dosage forms.
Preclinical studies have shown that lithium alters sodium transport in nerve and muscle cells and effects a shift toward intraneuronal metabolism of catecholamines, but the specific biochemical mechanism of lithium action in mania is unknown.
Lithium Carbonate Extended-Release Tablets are indicated in the treatment of manic episodes of manic-depressive illness. Maintenance therapy prevents or diminishes the intensity of subsequent episodes in those manic-depressive patients with a history of mania.
Typical symptoms of mania include pressure of speech, motor hyperactivity, reduced need for sleep, flight of ideas, grandiosity, elation, poor judgment, aggressiveness and possibly hostility. When given to a patient experiencing a manic episode, Lithium Carbonate Extended-Release Tablets may produce a normalization of symptomatology within 1 to 3 weeks.
The toxic concentrations for lithium (≥1.5 mEq/L) are close to the therapeutic range (0.8 to 1.2 mEq/L). Some patients abnormally sensitive to lithium may exhibit toxic signs at serum concentrations that are considered within the therapeutic range [see BOXED WARNING, DOSAGE AND ADMINISTRATION]. Lithium may take up to 24 hours to distribute into brain tissue, so occurrence of acute toxicity symptoms may be delayed.
Neurological signs of lithium toxicity range from mild neurological adverse reactions such as fine tremor, lightheadedness, lack of coordination, and weakness; to moderate manifestations like giddiness, apathy, drowsiness, hyperreflexia, muscle twitching, ataxia, blurred vision, tinnitus, and slurred speech; and severe manifestations such as clonus, confusion, seizure, coma, and death. In rare cases, neurological sequelae may persist despite discontinuing lithium treatment and may be associated with cerebellar atrophy. Cardiac manifestations involve electrocardiographic changes, such as prolonged QT interval, ST and T-wave changes and myocarditis. Renal manifestations include urine concentrating defect, nephrogenic diabetes insipidus, and renal failure. Respiratory manifestations include dyspnea, aspiration pneumonia, and respiratory failure. Gastrointestinal manifestations include nausea, vomiting, diarrhea, and bloating. No specific antidote for lithium poisoning is known [see OVERDOSAGE].
The risk of lithium toxicity is increased by: