Lithium
- 1. LITHIUM A Mood Stabilizer
- 2. Overview Facts about lithium Brief overview of Bipolar Disorder Augmenting combinations How lithium may work Side Effects Special Populations Drug Interactions Pharmacokinetics and important dosing tips
- 3. Facts About Lithium (Li) It is an ion whose mechanism of action is not certain Identified as the 1 st treatment for Bipolar Disorder Less effective for rapid cycling or mixed episodes It’s the 1 st psychotropic drug proven to have an effect in prevention of future episodes
- 4. Overview of Bipolar Disorder
- 5. Bipolar Disorder (cont’d) About 1% of the population are diagnosed with Bipolar Disorder (2-3 million) It is believed to be genetic Monozygotic– 80% Dizygotic– 8-10% No specific gene has been established Believed that no single genetic abnormality within the DNA causes psychiatric disorders Multiple sites in DNA must interact to produce the causation of a psychiatric disorder.
- 6. Augmenting Combinations Lithium can be used with the following, in cases of partial response or treatment resistance: Valproate Atypical antipsychotics (risperdone, olanzapine, aripiprazole) Some antidepressants CAUTION: antidepressants could potentially cause the patient to go into rapid cycling episodes or increase suicidal ideation (Avoid TCA’s and MAOI’s) Benzodiazepines
- 7. How Lithium is Thought to Work It alters Na+ transport across cell membranes in nerve and muscle cells It alters metabolism of NT’s including catecholamines and serotonin It alters intracellular signaling through actions on 2 nd messenger systems It inhibits inositol monophosphatase, affecting the phosphatidyl inositol 2 nd messenger system
- 8. How Lithium is Thought to Work (cont’d) It reduces protein kinase C activity It increases cytoprotective proteins It increases gray matter content, possibly by activating neurogenesis and enhancing trophic actions that maintain synapses
- 9. Side Effects Ataxia Dysarthria Delirium Tremor Memory problems Diarrhea, Nausea Weight Gain Polyuria & Polydipsia Leukocytosis Acne, rash, alopecia Sedation LIFE THREATENING Li toxicity Renal impairment Arrhythmia Bradycardia Hypotension Seizures Pseudotumor cerebri (intracranial pressure) Many cannot be improved by other medications Propranolol (ataxia) Diuretics
- 10. Do Not Prescribe to the Following Renal impairment Cardiac impairment Elderly Children under 12 Pregnant women Women that are breast feeding
- 11. Drug Interactions with Lithium Anti-inflammatory agents (ibuprofen), diuretics, and angiotensin-converting enzyme inhibitors can cause increased plasma lithium concentrations Carbamazepine (tegretol) and phenytoin (dilantin) can increase lithium toxicity Calcium channel blockers may also increase lithium toxicity SSRI’s may increase the risk of dizziness, confusion, diarrhea, agitation, and tremor
- 12. Pharmacokinetics Half life 18-30 hours How long until it works 1-3 weeks For immediate results, an atypical antipsychotic is recommended Forms of Li Tablet (300 mg, slow release; 450 mg, controlled release) Capsule (150 mg, 300 mg, 600 mg) Liquid (8 mEq/5 mL) Up to 1800 mg/day can be given in acute cases (divided) 900-1200 mg/day for maintenance (divided) 10 mL 3 times/day for acute mania; 5 mL 3-4 times/day for long-term use
- 13. Dosing Tips Kidney function tests and thyroid function tests MUST be done before adminisering Rapid discontinuation increases the risk of relapse and suicidal ideation. It needs to be tapered over 3 months Long-term use can cause reduced kidney function, so 1-2 times a year it should be checked Overdose can result in death or serious side effects (tremor, dysarthria, delirium, coma, seizures, and autonomic instability)
- 14. Any Questions? References Stahl, S. M. (2000). Essential psychopharmacology: neuroscientific basis and practical applications (2nd ed.). New York: Cambridge University Press. Stahl, S. M. (2005). The prescriber’s guide . New York: Cambridge University Press.