Lithium counteracts carbamazepine-induced leukopenia while increasing its therapeutic effect

Lithium Preparations in Psychiatry, Addiction Medicine and Neurology. Part II. Biochemical Mechanisms of Its Action

Lithium is the first and the lightest in the series of alkali metals, to which, in addition to lithium, two very biologically important elements – sodium and potassium, as well as trace elements rubidium and cesium, belong. Despite its formal affiliation to the group of alkali metals, lithium, like many other chemical elements of the «atypical» second period of the periodic table (for example, boron), is more similar in its chemical properties not to its counterparts in the group, but to its «diagonal brother» – magnesium. As we will show in this article, the diagonal chemical similarity between lithium and magnesium is of great importance for understanding the mechanisms of its intracellular biochemical action. At the same time, the intragroup chemical similarity of lithium with sodium and potassium is more important for understanding the mechanisms of its absorption, its distribution in the body and its excretion. Despite the 70 years that have passed since John Cade’s discovery of the antimanic effect of lithium, the mechanisms of its therapeutic action are still not completely understood. In the end, it turns out that the mechanism of the therapeutic action of lithium is extremely complex, multicomponent, unique and not imitable. Certain aspects of the mechanism of its action may be compatible with the mechanisms of action of other mood stabilizers, or with the mechanisms of action of so-called «lithium-mimetics», such as ebselen. However, no other drug to date failed to fully reproduce the biochemical effect of lithium on the body.

Haematological toxicity of drugs used in psychiatry

Almost all classes of psychotropic agents have been reported to cause blood dyscrasias. Mechanisms include direct toxic effects upon the bone marrow, the formation of antibodies against haematopoietic precursors or involve peripheral destruction of cells. Agranulocytosis is probably the most important drug-related blood dyscrasia. The mortality from drug-induced agranulocytosis is 5-10% in Western countries. The manifestations of agranulocytosis are secondary to infection. Aggressive treatment with intravenous broad-spectrum antimicrobials and bone marrow stimulants may be required. Of drugs encountered in psychiatry, antipsychotics including clozapine (risk of agranulocytosis approximately 0.8%, predominantly in the first year of treatment) and phenothiazines (chlorpromazine agranulocytosis risk approximately 0.13%), and antiepileptics (notably carbamazepine, neutropenia risk approximately 0.5%) are the most common causes of drug-related neutropenia/agranulocytosis. Drugs known to cause neutropenia should not be used concomitantly with other drugs known to cause this problem. High temperature and other indicators of possible infection should be looked for routinely during treatment. Clozapine is well known as a drug that can cause blood dyscrasias, but olanzapine and other atypicals may also cause similar problems. In addition to genetic factors, there are likely to be dose-related and immunological components to these phenomena. Important lessons have been learnt from the haematological monitoring that is necessary with clozapine and the monitoring has been very successful in preventing deaths related to clozapine-induced agranulocytosis. Continuing research into the mechanisms of drug-induced neutropenia and agranulocytosis may serve to further enhance the safe use not only of clozapine, but also of other agents.

Hematologic side effects of psychotropics

Psychiatrists are often unaware of the potential hematologic complications of the psychotropics they prescribe. Although this review is not a hematologic text reference, relevant hematologic syndromes are described so that the consultation-liaison psychiatrist will be familiar with the usual signs, symptoms, and treatments of these syndromes. This article reviews the hematologic side effects of the commonly prescribed psychotropics, including antipsychotics, antidepressants, benzodiazepines, lithium, mood stabilizers (including some of the anticonvulsants), and the acetylcholinesterase inhibitors. Clinical signs and symptoms that should alert the physician to obtain a complete blood count are described.

Management of treatment-resistant unipolar and chronically depressed patients

The majority of depressed patients presenting as treatment refractory will respond to a properly chosen new medication or to a previous agent administered correctly. Drug combinations are less frequently required than current practice would indicate, and their usage depends at present more on clinical experience than scientific fact. Educating the patient about the series of options available, and the sequence in which they will be undertaken, and imbuing the enterprise with hopeful optimism are essential ingredients to ultimate success.

Lithium treatment: a comparison of once- and twice-daily dosing

The effects of once- and twice-daily dosing with lithium carbonate were compared in a non-blind, cross-over study on 20 consecutive patients with mood disorders. Mental status, side effects and target organ function were examined after a minimum of a 1-month treatment with each regimen. Eighteen patients completed the study and 2 withdrew because of side effects. There were no significant differences between the 2 groups on the Hamilton Rating Scale for Depression, the Bech-Rafaelsen Mania Scale, the UKU Side Effects Scale or in serum lithium, electrocardiogram and urine volumes. Most blood tests showed no significant difference between the 2 treatment schedules except for white blood cells, ionized calcium and phosphate concentration. The once-daily regimen was associated with a higher white cell count, increased serum phosphate and elevated serum ionized calcium. We conclude that patients are able to tolerate once-daily dosing with lithium carbonate as well as twice-daily dosing.

Psychotropic drug use in the medically ill. Part II

Underlying medical illness and drug interactions may make the use of psychotropic agents problematic in some physically ill patients. This overview, published in two parts, discusses six major classes of psychotropic medications (cyclic antidepressants, monoamine oxidase inhibitors, benzodiazepines, neuroleptics, lithium, psychostimulants, and carbamazepine) and examines their use in the setting of specific types of medical illnesses (e.g., cardiovascular, pulmonary, hepatic, and renal disease). Practical considerations in using psychotropic medications in medical-surgical patients--particularly those who are elderly or medically debilitated--will receive special emphasis.

A review of carbamazepine's hematologic reactions and monitoring recommendations

Early case reports of fatal hematologic effects attributed to carbamazepine (CBZ) resulted in extensive monitoring recommendations by the manufacturer. The rarity of blood dyscrasias led many authors to question the manufacturer's guidelines. Thus the manufacturer removed specific monitoring guidelines, allowing physicians to monitor CBZ using their clinical judgment. This article reviews case reports and studies of CBZ's hematologic effects. Due to their rapid onset, daily laboratory checks would be necessary to monitor for aplastic anemia, agranulocytosis, and thrombocytopenia. These adverse effects are best monitored by informing patients and physicians to carefully watch for signs and symptoms. Leukopenia develops more slowly, occurring in approximately 12 percent of children and 7 percent of adults. Its onset is typically within the first three months of treatment, with patients at risk having a low or low-normal pretreatment white blood cell (WBC) count. Leukopenia often reverses, even if CBZ is continued. Based upon our review of the literature, we recommend monitoring of those high-risk patients during the first three months of treatment with the frequency being determined by results of each laboratory value. WBC counts less than 3000/mm3 or neutrophil counts below 1000/mm3 warrant a decrease in dose with frequent monitoring or CBZ discontinuation, if necessary.

Carbamazepine. What physicians should know about its hematologic effects

Transient leukopenia and, less commonly, neutropenia may occur with carbamazepine therapy. Discontinuation of therapy is usually not indicated unless symptoms are severe, persistent, or accompanied by infection. Patients with a low leukocyte or neutrophil count before treatment may be at increased risk for carbamazepine-induced leukopenia or neutropenia. Careful monitoring of blood counts, particularly during the first month of therapy, is essential. The frequency of monitoring can be determined on an individual basis. If a hematologic abnormality develops, the frequency of monitoring should be increased, especially if carbamazepine is not discontinued. Only when the neutrophil count falls below 500/mm3 does a severe risk of infection exist.

Adding lithium carbonate to carbamazepine: antimanic efficacy in treatment-resistant mania

Although lithium and carbamazepine used alone are effective in treating acute mania, some patients do not respond adequately to either of these medications used alone. We assessed, under double-blind conditions, a potential synergism between carbamazepine and lithium in the acute treatment of mania. Six of 7 manic patients who had previously been largely refractory to lithium alone, and who still showed substantial mania after several weeks of double-blind treatment with carbamazepine, improved following the blind addition of lithium. The clinical and theoretical implications of the response to this combination treatment are discussed.

Neutrophilia and lymphopenia in major mood disorders

Alterations in peripheral blood leukocyte distribution in major depression, including lymphopenia, neutrophilia, eosinopenia, and monocytopenia, have been described. The present study was designed to replicate these results, but with methodological improvements, including age-, sex-, and race-matched control subjects; DSM-III and Research Diagnostic Criteria diagnoses based on the Schedule for Affective Disorders and Schizophrenia interview; objective and subjective severity of depression measured quantitatively; and consideration of psychosocial stressors (DSM-III, Axis IV). We found relative lymphopenia and absolute neutrophilia and leukocytosis in depression, but did not find decreased numbers of eosinophils or monocytes. The relative lymphopenia and absolute neutrophilia were present in the subgroup of only unipolar depressed patients, but not in the bipolar, currently depressed subgroup. However, these blood cell changes were not found in a subgroup of patients who had been medication free greater than or equal to 1 month but only in the subgroup of patients using medication at the time of phlebotomy. Groups formed on the basis of psychosocial stress levels were not found to have significant significant intergroup differences in white blood cell (WBC) counts. The clinical significance of these findings needs study. While leukocytosis and neutrophilia can be found in major depression, these changes are perhaps secondary to medication use.