Enhancement of lithium elimination by multiple-dose sodium polystyrene sulfonate

Gastrointestinal decontamination in the acutely poisoned patient

Objective

To define the role of gastrointestinal (GI) decontamination of the poisoned patient.

Data Sources

A computer-based PubMed/MEDLINE search of the literature on GI decontamination in the poisoned patient with cross referencing of sources.

Study Selection and Data Extraction

Clinical, animal and in vitro studies were reviewed for clinical relevance to GI decontamination of the poisoned patient.

Data Synthesis

The literature suggests that previously, widely used, aggressive approaches including the use of ipecac syrup, gastric lavage, and cathartics are now rarely recommended. Whole bowel irrigation is still often recommended for slow-release drugs, metals, and patients who "pack" or "stuff" foreign bodies filled with drugs of abuse, but with little quality data to support it. Activated charcoal (AC), single or multiple doses, was also a previous mainstay of GI decontamination, but the utility of AC is now recognized to be limited and more time dependent than previously practiced. These recommendations have resulted in several treatment guidelines that are mostly based on retrospective analysis, animal studies or small case series, and rarely based on randomized clinical trials.

Conclusions

The current literature supports limited use of GI decontamination of the poisoned patient.

Successful treatment of lithium toxicity with sodium polystyrene sulfonate: a retrospective cohort study

CONTEXT

Lithium (Li) is a first-line treatment for bipolar disorder but has a narrow therapeutic index. Treatment of Li toxicity includes supportive measures and hemodialysis in severe cases, but this modality is not always immediately available. Sodium polystyrene sulfonate (SPS, Kayexalate), a cation exchanger, has been promising in animal models and human reports to reduce absorption and enhance elimination of Li.

MATERIAL AND METHODS

A retrospective cohort study was conducted. All cases of chronic Li intoxication were reviewed in two adult-care hospitals from 2000 to 2009. A group comparison and a within-patient comparison were performed to compare the effect of SPS on the median Li half-life (T(1/2)). For this study, at least three serum Li levels were required for T(1/2) calculations.

RESULTS

Forty-eight patients met inclusion requirements, 12 of whom had taken SPS. Median Li T(1/2) in the treated and control groups was 20.5 and 43.2 hours, respectively (p = 0.0006). In the 12 treated patients, Li T(1/2) during SPS was on average 48.9% shorter than without SPS. Furthermore, in one subject in whom urinary Li data were available, Li clearance with SPS was superior to Li renal clearance. Prolonged constipation was noted in one patient whereas mild hypokalemia was noted in six patients treated with SPS.

CONCLUSION

This study shows that SPS reduced Li T(1/2) and suggests that SPS is capable of promoting Li elimination in chronic intoxications. These results warrant a prospective trial looking at the use of SPS in the treatment of Li overdose as an adjunct to supportive measures and hemodialysis.

Evaluation of available treatment guidelines for the management of lithium intoxication

Intoxications with lithium carry considerable risk for long-term morbidity and even mortality. Consequently, any patient suspected of lithium intoxication requires immediate and appropriate care. The objectives of this study were to assess the completeness and the applicability of generally available treatment guidelines for the management of patients with a lithium intoxication and, hence, to provide general recommendations for improvement of existing treatment guidelines. Nineteen treatment guidelines originating from 7 different countries were gathered by searching the Internet, online databases, and textbooks and by contacting different poison information centers and university medical centers. A list of items was composed from the retrieved treatment guidelines and a further literature search. Most relevant items were present in the various guidelines. However, in some guidelines, essential information was missing or potentially hazardous information was provided. Clarity, presentation, and applicability of the guidelines, as assessed using parts of the Appraisal of Guidelines Research and Evaluation instrument, were relatively poor. Regular updates of treatment guidelines should be performed to incorporate new essential information. To improve applicability of guidelines, unambiguous key recommendations, alternative treatments, and special care requirements should be provided and authors are recommended to test treatment guidelines using a panel of less experienced caregivers in a hypothetical case scenario.

Sodium polystyrene sulfonate (Kayexalate) aspiration

In this short report we illustrate a case of extensive sodium polystyrene sulfonate (SPS) aspiration as an immediate cause of death in a terminally ill patient. SPS is a cation exchange resin utilized to decrease potassium levels in patients with renal failure. When administered rectally in conjunction with sorbitol, colonic necrosis and perforation have been documented. On the other hand, oral administration can be complicated by aspiration, especially in very ill or debilitated patients. In our current report, histological examination of a patient who aspirated SPS shows multiple polygonal to amorphous basophilic crystalline particles deposited intraalveolarly. The purpose of our report is to familiarize pathologists with the histologic features of this rare iatrogenic complication of therapy for hyperkalemia.

Management of Lithium Toxicity

Lithium salts have been used in the prophylaxis and treatment of depression and bipolar disorder for >50 years. Lithium has a narrow therapeutic range, and several well characterised adverse effects limit the potential usefulness of higher doses. Acute ingestion in lithium-naive patients is generally associated with only short-lived exposure to high concentrations, due to extensive distribution of lithium throughout the total body water compartment. Conversely, chronic toxicity and acute-on-therapeutic ingestion are associated with prolonged exposure to higher tissue concentrations and, therefore, greater toxicity. Lithium toxicity may be life threatening, or result in persistent cognitive and neurological impairment. Therefore, enhanced lithium clearance has been explored as a means of minimising exposure to high tissue concentrations. Although haemodialysis is highly effective in removing circulating lithium, serum concentrations often rebound so repeated or prolonged treatment may be required. Continuous arteriovenous haemodiafiltration and continuous venovenous haemodiafiltration increase lithium clearance, albeit to a lesser extent than haemodialysis, and are more widely accessible. Haemodiafiltration sustained for >16 hours allows effective removal of total body lithium, thereby avoiding rebound effects. Enhanced elimination should be considered in patients at greatest risk of severe poisoning: namely those with chronic or acute-on-therapeutic toxicity, those with clinically significant features, and those with chronic toxicity whose serum lithium concentration is >2.5 mmol/L. The choice between haemodialysis and continuous haemodiafiltration techniques will depend on local accessibility and urgency of enhancing lithium elimination. Further research is required to establish the potential benefits of assisted elimination on clinical outcome in patients with lithium poisoning.

Potassium repletion fails to interfere with reduction of serum lithium by sodium polystyrene sulfonate in mice

OBJECTIVES

Previous studies have shown that oral sodium polystyrene sulfonate (SPS) lowers serum lithium concentrations after acute and chronic toxic lithium exposures. Because hypokalemia may represent a deterrent to the clinical use of SPS for lithium intoxication, this study was designed to determine whether potassium (K+) repletion interferes with the effect of SPS on serum lithium.

METHODS

168 male, CD-1 mice were given lithium chloride (LiCl) (250 mg/kg) by gavage at time 0. Half of the mice were then given SPS (5 g/kg/dose) and half an equivalent volume of water by gavage at times 20 and 40 minutes. Half of each of these subgroups was then given potassium chloride (KCl) (3 mmol/kg) intraperitoneally and half an equivalent volume of normal saline. The animals were then sacrificed at one, two, four, and eight hours after lithium administration and the sera were analyzed for lithium and K+ by atomic absorption spectrophotometry. The groups were compared with analysis of variance.

RESULTS

The SPS lowered both lithium and K+ concentrations (ps < or = 0.0001). The KCl treatment was associated with transiently increased K+ concentrations (p < 0.0001) and with mildly elevated lithium concentrations when compared with the results of the animals not treated with KCl (p = 0.0016). The KCl treatment-associated increase in lithium concentration occurred both in the animals treated with water and in those treated with SPS.

CONCLUSIONS

Potassium repletion did not interfere with the ability of SPS to lower serum lithium concentration in animals experimentally poisoned with lithium.

Use of sodium polystyrene sulfonate for reduction of plasma lithium concentrations after chronic lithium dosing in mice

OBJECTIVES

Previous studies have shown that oral sodium polystyrene sulfonate lowers plasma lithium concentrations after acutely administered oral doses of lithium chloride. However, a significant proportion of lithium overdose cases resulting in morbidity and mortality are those in which exposure to lithium is chronic. This study was designed to determine whether multiple oral doses of sodium polystyrene sulfonate are effective in reducing plasma lithium concentrations after chronic dosing.

DESIGN

Placebo-controlled animal study.

INTERVENTIONS

One hundred thirty mice were given 75 mM lithium chloride in their drinking water for a period of 14 days. At the end of that period, half of the animals were given orogastric sodium polystyrene sulfonate at 5 g/kg/dose 0, 60, 120, 180, and 360 minutes after the cessation of lithium chloride; the remaining half received orogastric water at equivalent times. Subgroups of each group were sacrificed at 90, 150, 330, 480, 1440, and 2880 minutes after lithium chloride cessation and plasma analyzed for lithium content. Lithium concentrations were compared by analysis of variance and single degree of freedom contrasts. Significance was set at an alpha level of 0.05.

RESULTS

Lithium concentration was lower overall in the animals treated with sodium polystyrene sulfonate (p < .0001) and specifically at 150, 330, and 480 minutes after lithium chloride cessation (p < .05).

CONCLUSIONS

Repetitive oral doses of sodium polystyrene sulfonate effectively lowered plasma lithium concentrations. Further study may ultimately define a role for the use of sodium polystyrene sulfonate in the treatment of patients with chronic lithium toxicity.

Methods used to decrease lithium absorption or enhance elimination

OBJECTIVE

To review current methods, well documented and investigational, being used to decrease lithium absorption or enhance lithium elimination.

METHODS

The basic science and clinical literature on lithium were reviewed by a comprehensive Medline search from 1984 to 1996. Additional references were identified by reviewing the reference citations from the results of the Medline search.

RESULTS

Prevention of Absorption: Whole bowel irrigation has been demonstrated to be an effective means of enhancing lithium removal from the gastrointestinal tract. Sodium polystyrene sulfonate resin administration has been shown to be effective in binding lithium elimination in animal and human models. However, the lower limits of effective sodium polystyrene sulfonate dosing and the extent of potassium lowering in humans are questions that need to be answered before sodium polystyrene sulfonate resin can be recommended for routine, use. Enhancement of Elimination: Saline or forced diuresis is not effective in enhancing lithium elimination unless the patient is volume or sodium depleted. The use of continuous arteriovenous hemodiafiltration or low dose dopamine to enhance lithium elimination has only been documented in case reports. Intravenous aminophylline (theophylline) is not consistently effective and its risks outweigh possible benefits. The literature supports hemodialysis as a well documented and effective means of enhancing lithium elimination. Controversy exists over the appropriate indications for its initiation.

DISCUSSION

Given the wide interpatient variability in lithium pharmacokinetics, single case reports do not provide sufficient evidence of the effectiveness of a given method to enhance