Lithium (medication)

Medical uses

Lithium is used primarily for bipolar disorder. It is sometimes used when other treatments are not effective in a number of other conditions, including major depression, schizophrenia, and some psychiatric disorders in children. In mood disorders, of which bipolar is one, it decreases the risk of suicide. This benefit is not seen with other medications.

Bipolar disorder

Lithium carbonate treatment was previously considered to be unsuitable for children; however, more recent studies show its effectiveness for treatment of early-onset bipolar disorder in children as young as eight. The required dosage is slightly less than the toxic level, requiring close monitoring of blood levels of lithium carbonate during treatment. A limited amount of evidence suggests lithium carbonate may contribute to treatment of substance abuse for some people with bipolar disorder.

Suicide

High levels of naturally occurring lithium in drinking water have been associated with lower rates of suicide.

Monitoring

Those who use lithium should receive regular serum level tests and should monitor thyroid and kidney function for abnormalities, as it interferes with the regulation of sodium and water levels in the body, and can cause dehydration. Dehydration, which is compounded by heat, can result in increasing lithium levels. The dehydration is due to lithium inhibition of the action of antidiuretic hormone, which normally enables the kidney to reabsorb water from urine. This causes an inability to concentrate urine, leading to consequent loss of body water and thirst.

Lithium concentrations in whole blood, plasma, serum or urine may be measured using instrumental techniques as a guide to therapy, to confirm the diagnosis in potential poisoning victims or to assist in the forensic investigation in a case of fatal overdosage. Serum lithium concentrations are usually in the 0.5–1.3 mmol/l range in well-controlled people, but may increase to 1.8–2.5 mmol/l in those who accumulate the drug over time and to 3–10 mmol/l in acute overdose.

Lithium salts have a narrow therapeutic/toxic ratio, so should not be prescribed unless facilities for monitoring plasma concentrations are available. Doses are adjusted to achieve plasma concentrations of 0.4 to 1.2 mmol Li+
/l (lower end of the range for maintenance therapy and the elderly, higher end for children) on samples taken 12 hours after the preceding dose.

Side effects

Sources for the following lists.

Very Common (>10% incidence) adverse effects of lithium include

Confusion

Constipation (usually transient, but can persist in some)

Decreased memory

Diarrhea (usually transient, but can persist in some)

Dry mouth

EKG changes — usually benign changes in T waves.

Hand tremor (usually transient, but can persist in some)

Headache

Hyperreflexia — overresponsive reflexes.

Leukocytosis — elevated white blood cell count

Muscle weakness (usually transient, but can persist in some)

Myoclonus — muscle twitching.

Nausea (usually transient, but can persist in some)

Polydypsia — increased thirst.

Polyuria — increased urination.

Renal (kidney) toxicity which may lead to chronic kidney failure

Vomiting (usually transient, but can persist in some)

Vertigo

Weight gain

Common (1-10%) adverse effects include

Acne

Extrapyramidal side effects — movement-related problems such as muscle rigidity, parkinsonism, dystonia, etc.

Euthyroid goitre — i.e. the formation of a goitre despite normal thyroid functioning.

Hypothyroidism — a deficiency of thyroid hormone.

Hair loss/hair thinning

Rare/Uncommon (<1%) adverse effects include

Brugada syndrome — a potentially fatal abnormality in the electrical activity of the heart.

Coma

Erythema multiforme — a potentially fatal skin reaction

Hallucinations

Hypercalcaemia — elevated blood levels of calcium.

Hypermagnesaemia — elevated blood levels of magnesium.

Hyperparathyroidism — elevated blood levels of parathyroid hormone.

Hyperthyroidism — elevated blood concentrations of thyroid hormones.

Increased intracranial pressure and papilledema

Myasthenia gravis — an autoimmune condition where the body's own defences attack the neuromuscular junction — the gap across which the nerves communicate with the muscles — leading to muscle weakness.

Oedema

Pseudotumor cerebri

Renal interstitial fibrosis

Seizure

Sinus node dysfunction

Transient reduction in peripheral circulation as a whole

Unknown frequency adverse effects include

Abdominal pain

Albuminuria — protein in the urine, a sign of impaired kidney function.

Bradycardia — low heart rate.

Changes in taste

Decreased creatinine clearance — another sign of impaired kidney function.

Flatulence

Gastritis

Glycosuria — glucose (blood sugar) in the urine.

Hyperthermia

Hypotension — low blood pressure.

Indigestion

Nystagmus — involuntary eye movements that can interfere with vision.

Oliguria — low urine output, although excess urine output is more likely.

Sexual dysfunction including impotence, decreased libido, vaginal dryness, erectile dysfunction, etc.

Slurred speech

Somnolence

Weight loss (gain is more common with prolonged treatment).

Lithium is known to be responsible for 1–2 kg of weight gain. Weight gain may be a source of low self-esteem for the clinically depressed.

In addition to tremors, lithium treatment appears to be a risk factor for development of parkinsonism symptoms, although the causal mechanism remains unknown.

Most side effects of lithium are dose-dependent. The lowest effective dose is used to limit the risk of side effects.

Hypothyroidism

Most patients treated with lithium carbonate show elevated thyroid stimulating hormone levels in response to injections of thyrotropin-releasing hormone. According to an Australian study, "The incidence of hypothyroidism is six-fold higher in people on lithium as compared to the general population. Hypothyroidism in turn increases the likelihood of developing clinical depression."

Because lithium competes with the receptors for the antidiuretic hormone in the kidney, it increases water output into the urine, a condition called nephrogenic diabetes insipidus. Clearance of lithium by the kidneys is usually successful with certain diuretic medications, including amiloride and triamterene. It increases the appetite and thirst ("polydypsia") and reduces the activity of thyroid hormone (hypothyroidism). The latter can be corrected by treatment with thyroxine and does not require the lithium dose to be adjusted. Lithium is also believed to permanently affect renal function, although this does not appear to be common.

Pregnancy and breast feeding

Lithium is a teratogen, causing birth defects in a small number of newborn babies. Case reports and several retrospective studies have demonstrated possible increases in the rate of a congenital heart defect known as Ebstein's anomaly, if taken during a woman's pregnancy. As a consequence, fetal echocardiography is routinely performed in pregnant women taking lithium to exclude the possibility of cardiac anomalies. Lamotrigine seems to be a possible alternative to lithium in pregnant women. Gabapentin and clonazepam are also indicated as antipanic medications during the childbearing years and during pregnancy. Valproic acid and carbamazepine also tend to be associated with teratogenicity.

While it appears to be safe to use while breastfeeding a number of guidelines list it as a contraindication including the British National Formulary.

Dehydration

Dehydration in people taking lithium salts can be very hazardous, especially when combined with lithium-induced nephrogenic diabetes insipidus with polyuria. Such situations include preoperative fluid restrictions, warm weather conditions, sporting events, hiking, or other periods of fluid inaccessibility. Dehydration can result in increased plasma lithium levels due to decreased glomerular filtration rate, which causes lithium retention. Further, in the case of diabetes insipidus, free water is lost in greater proportion to sodium and other electrolytes, artificially raising lithium's concentration in the blood.

Another danger is that if the period of dehydration and diuresis has been prolonged, total body stores of sodium may actually be depleted, despite elevated plasma levels. Thus, rapid hydration with a large volume of plain water may very quickly produce hyponatremia, as total stores of sodium may be insufficient to support normal concentrations at a normal blood volume. Rapid overcorrection of hyponatremia also increases the risk of developing cerebral edema. Hyponatremia can also promote lithium retention by increasing reabsorption in the distal nephron, thus increasing lithium levels.

Kidney damage

Lithium has been associated with several forms of kidney injury. It is estimated that impaired urinary concentrating ability is present in at least 50% of individuals on chronic lithium therapy - lithium-induced nephrogenic diabetes insipidus Continued use of lithium can lead to more serious kidney damage, aggravated form of diabetes insipidus. and chronic kidney failure. CKD is found in about one third of people undergoing long-term lithium treatment, according to one study. Some forms of lithium-caused kidney damage may be progressive and lead to end-stage kidney failure.

Interactions

Lithium concentrations are known to be increased with concurrent use of diuretics — especially loop diuretics (such as furosemide) and thiazides — and non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen. Lithium concentrations can also be increased with concurrent use of ACE inhibitors such as captopril, enalapril, and lisinopril.

Lithium is mainly removed from the body through glomerular function, but some is then reabsorbed together with sodium through the proximal tubule. Its levels are therefore sensitive to water and electrolyte balance. Diuretics act by lowering water and sodium levels; this causes more reabsorption of lithium in the proximal tubules so that the removal of lithium from the body is less, leading to increased levels of lithium. ACE inhibitors have also been shown in a retrospective case-control study to increase lithium concentrations. This is likely due to constriction of the afferent arteriole of the glomerulus, resulting in decreased glomerular filtration rate and clearance. Another possible mechanism is that ACE inhibitors can lead to a decrease in sodium and water. This will increase lithium reabsorption and its concentrations in the body.

There are also drugs that can increase the clearance of lithium from the body, which can result in decreased lithium levels in the blood. These drugs include theophylline, caffeine, and acetazolamide. Additionally, increasing dietary sodium intake may also reduce lithium levels by prompting the kidneys to excrete more lithium.

Lithium is also known to be a potential precipitant of serotonin syndrome in people concurrently on serotonergic medications such as antidepressants, buspirone and certain opioids such as pethidine (meperidine), tramadol, oxycodone, fentanyl and others. Lithium co-treatment is also a risk factor for neuroleptic malignant syndrome in people on antipsychotics and other antidopaminergic medications.

High doses of haloperidol, fluphenazine, or flupenthixol may be hazardous when used with lithium; irreversible toxic encephalopathy has been reported. Indeed, these and other antipsychotics have been associated with increased risk of lithium neurotoxicity, even with low therapeutic lithium doses.

Overdose

Lithium toxicity may occur on an acute basis, in persons taking excessive amounts either accidentally or intentionally, or on a chronic basis, in people who accumulate high levels during ongoing therapy. The manifestations include nausea, emesis, diarrhea, asthenia, ataxia, confusion, lethargy, polyuria, seizures and coma. Other toxic effects of lithium include coarse tremor, muscle twitching, convulsions and renal failure. People who survive a poisoning episode may develop persistent neurotoxicity. Several authors have described a "Syndrome of Irreversible Lithium-Effected Neurotoxicity" (SILENT), associated with episodes of acute lithium toxicity or long-term treatment within the appropriate dosage range. Symptoms are said to include cerebellar dysfunction.

Overdosage, usually with plasma concentrations over 1.5 mmol Li+
/l, may be fatal, and toxic effects include tremor, ataxia, dysarthria, nystagmus, renal impairment, confusion, and convulsions. If these potentially hazardous signs occur, treatment should be stopped, plasma lithium concentrations redetermined, and steps taken to reverse lithium toxicity.

Lithium toxicity is compounded by sodium depletion. Concurrent use of diuretics that inhibit the uptake of sodium by the distal tubule (e.g. thiazides) is hazardous and should be avoided because this can cause increased resorption of lithium in the proximal convoluted tubule, leading to elevated, potentially toxic levels. In mild cases, withdrawal of lithium and administration of generous amounts of sodium and fluid will reverse the toxicity. Plasma concentrations in excess of 2.5 mmol Li+
/l are usually associated with serious toxicity requiring emergency treatment. When toxic concentrations are reached, there may be a delay of one or two days before maximum toxicity occurs.

In long-term use, therapeutic concentrations of lithium have been thought to cause histological and functional changes in the kidney. The significance of such changes is not clear, but is of sufficient concern to discourage long-term use of lithium unless it is definitely indicated. Doctors may change a bipolar patient's medication from lithium to another mood-stabilizing drug, such as valproate (Depakote), if problems with the kidneys arise. An important potential consequence of long-term lithium use is the development of renal diabetes insipidus (inability to concentrate urine). Patients should therefore be maintained on lithium treatment after three to five years only if, on assessment, benefit persists. Conventional and sustained-release tablets are available. Preparations vary widely in bioavailability, and a change in the formulation used requires the same precautions as initiation of treatment. There are few reasons to prefer any one simple salt of lithium; the carbonate has been the more widely used, but the citrate is also available.

Mechanism of action

The specific biochemical mechanism of lithium action in stabilizing mood is unknown.

Upon ingestion, lithium becomes widely distributed in the central nervous system and interacts with a number of neurotransmitters and receptors, decreasing norepinephrine release and increasing serotonin synthesis.

Unlike many other psychoactive drugs, Li+
typically produces no obvious psychotropic effects (such as euphoria) in normal individuals at therapeutic concentrations. Lithium may also increase the release of serotonin by neurons in the brain. In vitro studies performed on serotonergic neurons from rat raphe nuclei have shown that when these neurons are treated with lithium, serotonin release is enhanced during a depolarization compared to no lithium treatment and the same depolarization.

Several authors proposed that pAp-phosphatase could be one of the therapeutic targets of lithium. This hypothesis was supported by the low Ki of lithium for human pAp-phosphatase compatible within the range of therapeutic concentrations of lithium in the plasma of people (0.8–1 mM). Importantly, the Ki of human pAp-phosphatase is ten times lower than that of GSK3β (glycogen synthase kinase 3β). Inhibition of pAp-phosphatase by lithium leads to increased levels of pAp (3′-5′ phosphoadenosine phosphate), which was shown to inhibit PARP-1

Another mechanism proposed in 2007 is that lithium may interact with nitric oxide (NO) signalling pathway in the central nervous system, which plays a crucial role in the neural plasticity. The NO system could be involved in the antidepressant effect of lithium in the Porsolt forced swimming test in mice. It was also reported that NMDA receptor blockage augments antidepressant-like effects of lithium in the mouse forced swimming test, indicating the possible involvement of NMDA receptor/NO signaling in the action of lithium in this animal model of learned helplessness.

Lithium possesses neuroprotective properties by preventing apoptosis and increasing cell longevity.

Although the search for a novel lithium-specific receptor is ongoing, the high concentration of lithium compounds required to elicit a significant pharmacological effect leads mainstream researchers to believe that the existence of such a receptor is considered to be unlikely.

Oxidative metabolism

Evidence suggests that mitochondrial dysfunction is present in patients with bipolar disorder. Oxidative stress and reduced levels of anti-oxidants (such as glutathione) lead to cell death. Lithium may protect against oxidative stress by up-regulating complex I and II of the mitochondrial electron transport chain.

Dopamine and G-protein coupling

During mania, there is an increase in neurotransmission of dopamine that causes a secondary homeostatic down-regulation, resulting in decreased neurotransmission of dopamine, which can cause depression. Additionally, the post-synaptic actions of dopamine are mediated through G-protein coupled receptors. Once dopamine is coupled to the G-protein receptors, it stimulates other secondary messenger systems that modulate neurotransmission. Studies found that in autopsies (which do not necessarily reflect living people), people with bipolar disorder had increased G-protein coupling compared to people without bipolar disorder. Lithium treatment alters the function of certain subunits of the dopamine associated G-protein, which may be part of its mechanism of action.

Glutamate and NMDA receptors

Glutamate levels are observed to be elevated during mania. Lithium is thought to provide long-term mood stabilization and have anti-manic properties by modulating glutamate levels. It is proposed that lithium competes with magnesium for binding to NMDA glutamate receptor, increasing the availability of glutamate in post-synaptic neurons. The NMDA receptor is also affected by other neurotransmitters such as serotonin and dopamine. Effects observed appear exclusive to lithium and have not been observed by other monovalent ions such as rubidium and caesium.

GABA receptors

GABA is an inhibitory neurotransmitter that plays an important role in regulating dopamine and glutamate neurotransmission. It was found that patients with bipolar disorder had lower GABA levels, which results in excitotoxicity and can cause apoptosis (cell loss). Lithium counteracts these degrading processes by decreasing pro-apoptotic proteins and stimulating release of neuroprotective proteins.

Cyclic AMP secondary messengers

The cyclic AMP secondary messenger system is shown to be modulated by lithium. Lithium was found to increase the basal levels of cyclic AMP but impair receptor coupled stimulation of cyclic AMP production. It is hypothesized that the dual effects of lithium are due the inhibition of G-proteins that then mediate cyclic AMP production. Over a long period of lithium treatment, cyclic AMP and adenylate cyclase levels are further changed by gene transcription factors.

Inositol depletion hypothesis

Lithium treatment has been found to inhibit the enzyme inositol monophosphatase, involved in degrading inositol monophosphate to inositol required in PIP₂ synthesis. This leads to lower levels of inositol triphosphate, created by decomposition of PIP₂. This effect has been suggested to be further enhanced with an inositol triphosphate reuptake inhibitor. Inositol disruptions have been linked to memory impairment and depression. It is known with good certainty that signals from the receptors coupled to the phosphoinositide signal transduction is effected by lithium. myo-inositol is also regulated by the high affinity sodium mI transport system (SMIT). Lithium is hypothesized to inhibit mI entering the cells and mitigating the function of SMIT. Reductions of cellular levels of myo-inositol results in the inhibition of the phosphoinositide cycle

Intracellular calcium

In 2014, it was proposed that lithium treatment works by affecting calcium signaling by blocking excitotoxic processes such as antagonizing NMDA receptors and inhibiting inositol monophosphatase (IMPase).

History

Lithium was first used in the 19th century as a treatment for gout after scientists discovered that, at least in the laboratory, lithium could dissolve uric acid crystals isolated from the kidneys. The levels of lithium needed to dissolve urate in the body, however, were toxic. Because of prevalent theories linking excess uric acid to a range of disorders, including depressive and manic disorders, Carl Lange in Denmark and William Alexander Hammond in New York City used lithium to treat mania from the 1870s onwards. By the turn of the 20th century, as theory regarding mood disorders evolved and so-called "brain gout" disappeared as a medical entity, the use of lithium in psychiatry was largely abandoned. Some suggest that the pharmaceutical industry was reluctant to invest in a drug that could not be patented, however a number of lithium preparations were yet produced for the control of renal calculi and ‘‘uric acid diathesis’’. As accumulating knowledge indicated a role for excess sodium intake in hypertension and heart disease, lithium salts were prescribed to patients for use as a replacement for dietary table salt (sodium chloride). This practice and the sale of lithium itself were both banned in 1949, following publication of reports detailing side effects and deaths.

Also in 1949, the Australian psychiatrist John Cade rediscovered the usefulness of lithium salts in treating mania. Cade was injecting rodents with urine extracts taken from schizophrenic patients in an attempt to isolate a metabolic compound which might be causing mental symptoms. Since uric acid in gout was known to be psychoactive, (adenosine receptors on neurons are stimulated by it; caffeine blocks them), Cade needed soluble urate for a control. He used lithium urate, already known to be the most soluble urate compound, and observed that it caused the rodents to become tranquil. Cade traced the effect to the lithium ion itself, and so proposed lithium salts as tranquilizers. He soon succeeded in controlling mania in chronically hospitalized patients with them. This was one of the first successful applications of a drug to treat mental illness, and it opened the door for the development of medicines for other mental problems in the next decades.

The rest of the world was slow to adopt this treatment, largely because of deaths which resulted from even relatively minor overdosing, including those reported from use of lithium chloride as a substitute for table salt. Largely through the research and other efforts of Denmark's Mogens Schou and Paul Baastrup in Europe, and Samuel Gershon and Baron Shopsin in the U.S., this resistance was slowly overcome. The application of lithium in manic illness was approved by the United States Food and Drug Administration in 1970. In 1974, this application was extended to its use as a preventive agent for manic-depressive illness.

Ronald R. Fieve, who had opened the first lithium clinic in North America in 1966, helped popularize the psychiatric use of lithium through his national TV appearances and his bestselling book, Moodswing. In addition, Fieve and David L. Dunner developed the concept of 'rapid cycling' Bipolar Disorder based on non-response to lithium.

Lithium has now become a part of Western popular culture. Characters in Pi, Premonition, Stardust Memories, American Psycho, Garden State, and An Unmarried Woman all take lithium. Sirius XM Satellite Radio in North America has a 1990s alternative rock station called Lithium, and several songs refer to the use of lithium as a mood stabilizer. These include: "Equilibrium met Lithium" by South African artist Koos Kombuis, "Lithium" by Evanescence, "Lithium" by Nirvana, "Lithium and a Lover" by Sirenia, "Lithium Sunset", from the album Mercury Falling by Sting, and "Lithium" by Thin White Rope.

7 Up

As with cocaine in Coca-Cola, lithium was widely marketed as one of a number of patent medicine products popular in the late-19th and early-20th centuries, and was the medicinal ingredient of a refreshment beverage. Charles Leiper Grigg, who launched his St. Louis-based company The Howdy Corporation, invented a formula for a lemon-lime soft drink in 1920. The product, originally named "Bib-Label Lithiated Lemon-Lime Soda", was launched two weeks before the Wall Street Crash of 1929. It contained the mood stabilizer lithium citrate, and was one of a number of patent medicine products popular in the late-19th and early-20th centuries. Its name was soon changed to 7 Up. All American beverage makers were forced to remove lithium in 1948. Despite the 1948 ban, in 1950 the Painesville Telegraph still carried an advertisement for a lithiated lemon beverage.

Names

Lithium carbonate (Li
2CO
3), sold under several trade names, is the most commonly prescribed, while lithium citrate (Li
3C
6H
5O
7) is also used in conventional pharmacological treatments. Lithium orotate (C
5H
3LiN
2O
4), has been presented as an alternative. Lithium bromide and lithium chloride have been used in the past as table salt; however, they fell out of use in the 1940s, when it was discovered they were toxic in those large doses. Many other lithium salts and compounds exist, such as lithium fluoride and lithium iodide, but they are presumed to be toxic as well and have never been evaluated for pharmacological effects.

Brand names include Camcolit (UK), Eskalith (US), Li-Liquid (UK), Liskonum (UK), Lithicarb (Australia), Lithobid (US), Priadel (UK), Quilonum (Australia), and Lithosun (India).

Research

Lithium may protect the brain and encourage the growth of gray matter in the cerebral cortex and prevent and slow the progression of Alzheimer's disease, senile dementia and Parkinson's disease.

However, for the amyotrophic lateral sclerosis (ALS), lithium has failed to produce positive results.