LITHONATE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for LITHONATE (LITHONATE).
Lithium modulates neurotransmitter activity in the central nervous system, including inhibition of inositol monophosphatase, leading to reduced phosphoinositide signaling; alters G-protein coupled receptor signaling; and inhibits glycogen synthase kinase-3 (GSK-3). It also affects ion transport, including sodium and potassium, and stabilizes neuronal excitability.
| Metabolism | Lithium is not metabolized; it is excreted renally almost entirely unchanged. It is filtered by the glomerulus and reabsorbed in the proximal tubule. Its elimination is affected by sodium balance and renal function. |
| Excretion | Primarily renal excretion (>95% as unchanged lithium); less than 5% excreted in feces via bile. |
| Half-life | Terminal elimination half-life 18-36 hours in young adults, up to 48-72 hours in elderly or with renal impairment; steady state reached in 5-7 days. |
| Protein binding | Not protein bound (0% bound). |
| Volume of Distribution | 0.7-1.0 L/kg; distributes into total body water, with higher concentration in thyroid and bone. |
| Bioavailability | Oral: 90-100% (immediate-release); sustained-release ~60-90% due to slower dissolution. |
| Onset of Action | Oral: 1-2 weeks for initial antimanic effect; full therapeutic effect 2-3 weeks. |
| Duration of Action | Plasma levels maintained with regular dosing; serum half-life determines dosing interval; narrow therapeutic window (0.6-1.2 mEq/L). |
300-600 mg orally 2-3 times daily for acute mania; 600-1200 mg/day in divided doses for maintenance. Titrate to serum lithium level 0.8-1.2 mEq/L (acute) or 0.6-1.2 mEq/L (maintenance).
| Dosage form | CAPSULE |
| Renal impairment | Contraindicated if GFR < 30 mL/min. For GFR 30-59 mL/min: use 50-75% of normal dose and monitor serum lithium levels every 2-3 days. For GFR ≥ 60 mL/min: no adjustment needed, but monitor levels frequently. |
| Liver impairment | No specific dose adjustment recommended for hepatic impairment. However, lithium is not metabolized by liver; no Child-Pugh based modifications are established. Use with caution if severe hepatic disease due to potential electrolyte imbalances. |
| Pediatric use | Children ≥ 12 years: 15-20 mg/kg/day in 2-3 divided doses, not to exceed 600 mg/day initially. Adjust based on serum levels targeting 0.6-1.2 mEq/L. For children < 12 years: safety and efficacy not established; use only if clearly needed. |
| Geriatric use | Start at 300 mg once daily or 150 mg twice daily. Reduce target serum lithium levels to 0.4-0.8 mEq/L. Monitor renal function and thyroid function more frequently due to age-related decline in GFR and increased sensitivity. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for LITHONATE (LITHONATE).
| Breastfeeding | Lithium excreted into breast milk; M/P ratio 0.3-0.5. Infant serum levels 10-50% of maternal. Monitor infant for lethargy, hypotonia, and feeding difficulties. Avoid if possible, especially in neonates or if maternal levels high. |
| Teratogenic Risk | First trimester exposure increases risk of Ebstein's anomaly (0.1% absolute risk) and neural tube defects. Second/third trimester: neonatal hypothyroidism, nephrogenic diabetes insipidus, floppy infant syndrome, and cardiac effects. Risk of preterm birth and low birth weight. |
■ FDA Black Box Warning
Lithium toxicity is closely related to serum lithium concentrations and can occur at doses close to therapeutic levels. Monitoring of serum lithium levels is required due to narrow therapeutic index. Toxicity is increased with dehydration, sodium depletion, or concurrent use of NSAIDs, diuretics, or ACE inhibitors.
| Serious Effects |
["Hypersensitivity to lithium or any component of the formulation","Advanced renal failure (creatinine clearance <30 mL/min)","Severe cardiovascular disease (e.g., sick sinus syndrome, bradyarrhythmias)","Untreated hypothyroidism (relative contraindication)","Concurrent use with NSAIDs, diuretics, or ACE inhibitors may require dose adjustment; not absolute contraindication but caution"]
| Precautions | ["Toxicity: narrow therapeutic index; monitor serum lithium levels regularly","Renal impairment: risk of lithium accumulation; adjust dose and monitor renal function","Thyroid effects: can cause hypothyroidism; monitor thyroid function tests","Neurologic effects: risk of tremor, sedation, and extrapyramidal symptoms; caution with concomitant antipsychotics","Cardiac effects: may cause T-wave changes, sinus node dysfunction; caution in patients with cardiovascular disease","Dehydration and sodium depletion increase risk of toxicity; maintain adequate hydration and sodium intake","Use with NSAIDs, diuretics, or ACE inhibitors increases lithium levels; monitor closely"] |
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| Fetal Monitoring |
| Check lithium levels every 4 weeks during pregnancy and weekly after 36 weeks. Monitor thyroid and renal function. Fetal echocardiogram at 18-22 weeks. Postnatal: monitor infant for hypoglycemia, goiter, and cardiac function. |
| Fertility Effects | No direct effect on fertility, but lithium may cause menstrual irregularities and polycystic ovary-like changes. Conception counseling recommended. |