Benefit of hemoperfusion in acute theophylline intoxication

Common Substances of Abuse

Adolescent substance abuse remains common, with almost a third of adolescents admitting to ethanol use, and a quarter admitting to illicit drug use. It is essential for pediatricians to regularly screen adolescent patients for substance use, because early initiation of drug use has been associated with physical, behavioral, and social health risks. Adolescents abuse what is common and readily available; this includes ethanol, over-the-counter products, marijuana, and inhalants. The most common and effective clinical treatments for significant toxicity from substances of abuse is symptomatic and supportive care including hemodynamic support, respiratory support, and sedation to control psychomotor agitation.

Intermittent haemodialysis and sustained low-efficiency dialysis (SLED) for acute theophylline toxicity

INTRODUCTION

Theophylline overdose can result in significant cardiovascular and neurologic toxicity and is potentially fatal. Clearance of theophylline can be enhanced by the administration of multiple-dose activated charcoal (MDAC) and extracorporeal elimination techniques. We report a case of severe theophylline toxicity initially treated with MDAC and intermittent haemodialysis. Subsequent to this, sustained low-efficiency dialysis (SLED) was undertaken. This is a prolonged renal replacement therapy that uses blood and dialysate flow rates between those of intermittent haemodialysis and continuous renal replacement therapy.

CASE REPORT

A 61-year-old man presented following ingestion of 24 g of theophylline SR (300 mg/kg), 240 mg of diazepam and 2 g of gabapentin. He required intubation and developed a supraventricular tachycardia treated with esmolol, but suffered no seizures. Serum theophylline concentration peaked at 636 μmol/L (55-110) at 9.5 h post-ingestion. Intermittent haemodialysis was performed for 4 h and resulted in a theophylline extraction ratio of 0.57 with elimination half-life of 2.3 h. SLED was subsequently performed on two occasions for 7 h. Theophylline extraction ratio ranged from 0.46 (half-life 5.3 h during the first cycle) to 0.61 (half-life 10.6 h during the second cycle). After cessation of SLED, elimination half-life was 26 h. The patient made an uneventful recovery.

DISCUSSION

Intermittent haemodialysis is the current recommended extracorporeal technique for enhancing theophylline elimination in the absence of charcoal haemoperfusion. However, SLED produced similar apparent extraction ratios with longer associated elimination half-life for theophylline than for intermittent haemodialysis. SLED is undertaken by intensive care unit (ICU) staff and may be a useful extracorporeal elimination technique in cases where access to intermittent haemodialysis, requiring specialist dialysis nursing staff, is limited or may be delayed.

Extracorporeal treatment for theophylline poisoning: systematic review and recommendations from the EXTRIP workgroup

BACKGROUND

The Extracorporeal Treatments in Poisoning workgroup was created to provide evidence-based recommendations on the use of extracorporeal treatments (ECTRs) in poisoning. Here, the workgroup presents its systematic review and recommendations for theophylline.

METHODS

After a systematic review of the literature, a subgroup reviewed articles, extracted data, summarized findings, and proposed structured voting statements following a pre-determined format. A two-round modified Delphi method was chosen to reach a consensus on voting statements and the RAND/UCLA Appropriateness Method was used to quantify disagreement. Anonymous votes were compiled, returned, and discussed. A second vote determined the final recommendations.

RESULTS

141 articles were included: 6 in vitro studies, 4 animal studies, 101 case reports/case series, 7 descriptive cohorts, 4 observational studies, and 19 pharmacokinetic studies, yielding a low-to-very-low quality of evidence for all recommendations. Data on 143 patients were reviewed, including 10 deaths. The workgroup concluded that theophylline is dialyzable (level of evidence = A) and made the following recommendations: ECTR is recommended in severe theophylline poisoning (1C). Specific recommendations for ECTR include a theophylline concentration [theophylline] > 100 mg/L (555 μmol/L) in acute exposure (1C), the presence of seizures (1D), life-threatening dysrhythmias (1D) or shock (1D), a rising [theophylline] despite optimal therapy (1D), and clinical deterioration despite optimal care (1D). In chronic poisoning, ECTR is suggested if [theophylline] > 60 mg/L (333 μmol/L) (2D) or if the [theophylline] > 50 mg/L (278 μmol/L) and the patient is either less than 6 months of age or older than 60 years of age (2D). ECTR is also suggested if gastrointestinal decontamination cannot be administered (2D). ECTR should be continued until clinical improvement is apparent or the [theophylline] is < 15 mg/L (83 μmol/L) (1D). Following the cessation of ECTR, patients should be closely monitored. Intermittent hemodialysis is the preferred method of ECTR (1C). If intermittent hemodialysis is unavailable, hemoperfusion (1C) or continuous renal replacement therapies may be considered (3D). Exchange transfusion is an adequate alternative to hemodialysis in neonates (2D). Multi-dose activated charcoal should be continued during ECTR (1D).

CONCLUSION

Theophylline poisoning is amenable to ECTRs. The workgroup recommended extracorporeal removal in the case of severe theophylline poisoning.

Hemoperfusion for the treatment of poisoning: technology, determinants of poison clearance, and application in clinical practice

Hemoperfusion is an extracorporeal treatment based on adsorption, historically reserved for the treatment of acute poisonings. Its use was popularized in the 1970s after several in vitro and animal experiments had demonstrated its efficacy, and was even preferred over hemodialysis in the management of overdosed patients. With the advent of new and more efficient dialytic modalities, hemoperfusion is now less frequently performed in the Western world. However, hemoperfusion still remains popular in developing countries. The present article reviews the technique of hemoperfusion, the factors influencing poison clearance through adsorption and its current applications.

A stepwise approach for the management of poisoning with extracorporeal treatments

The use of an extracorporeal treatment (ECTR) in a poisoned patient may be life-saving in a limited number of scenarios. The decision-processes surrounding the use of ECTR in poisoning is complex: most nephrologists are not trained to assess a poisoned patient while clinical toxicologists rarely prescribe ECTRs. Deciding on which ECTR is most appropriate for a poison requires a good understanding of the poison's physicochemical and pharmacokinetic properties. Further, a detailed understanding of the capabilities and limitations of the different ECTRs can be useful to select the most appropriate ECTR for a given clinical situation. This manuscript provides a stepwise approach to assess the usefulness of ECTRs in poisoning.

The cardiovascular effects of methylxanthines

In the concentration range that is normally achieved in humans, e.g., after the drinking of coffee or in patients treated with theophylline, the cardiovascular effects of methylxanthines are primarily due to antagonism of adenosine A(1) and A(2) receptors. Inhibition of phosphodiesterases or mobilization of intracellular calcium requires much higher concentrations. In conscious humans, acute exposure to caffeine results in an increase in blood pressure by an increased total peripheral resistance, and a slight decrease in heart rate. This overall hemodynamic response is composed of direct effects of caffeine on vascular tone, on myocardial contractility and conduction, and on the sympathetic nervous system. Caffeine is the most widely consumed methylxanthine, mainly derived from coffee intake. Regular coffee consumption can affect various traditional cardiovascular risk factors, including a slight increase in blood pressure, an increase in plasma cholesterol and homocysteine levels, and a reduced incidence of type 2 diabetes mellitus. Although most prospective studies have not reported an association between coffee consumption and coronary heart disease, these findings do not exclude that the acute hemodynamic and neurohumoral effects of coffee consumption could have an adverse effect in selected patient groups who are more vulnerable for these effects, based on their genetic profile or medication use.

Acute hemolysis with acute renal failure in a patient with valproic acid poisoning treated with charcoal hemoperfusion

Hemoperfusion consists of the passage of anticoagulated blood through a column containing adsorbent particles. It was introduced in 1940 and refined from 1950 to 1970, and then introduced clinically for the treatment of acute intoxications between 1970 and 1980. Life-threatening valproic acid toxicity is an indication for coated charcoal hemoperfusion usually accomplished without complications, but we report a case of acute severe intravascular hemolysis during the time of hemoperfusion with coated charcoal column.

Oral theophylline changes renal carnitine palmitoyltransferase activity in rats

BACKGROUND

Carnitine plays a critical role in lipid metabolism. Carnitine deficiency may adversely affect the oxidation of fatty acids and further aggravate abnormal lipid metabolism. Our objective was to investigate the effect of theophylline on the activity of carnitine palmitoyltransferase (CPT) in renal tissues of rats for 5-week-interval treatments.

METHODS

The study was a randomized, controlled animal study. Theophylline was given at 100 mg/kg body weight (b.w.)/day and effects were monitored after a treatment period of between 1 and 5 weeks.

RESULTS

Theophylline treatment caused a significant increase in renal CPT activity as compared to either control or placebo groups. Moreover, the results showed positive correlations between the renal concentration of long-chain acylcarnitine (LC), activity of CPT, urinary excretion of acylcarnitine (AC), and plasma concentration of LC (p <0.01), respectively.

CONCLUSIONS

The observed changes in activity of renal CPT might be due to the result from theophylline-enhanced mobilization of lipid from adipose tissues that consequently stimulated an increased carnitine transport into the renal tissues to form palmitoylcarnitine groups for subsequent beta-oxidation inside the mitochondria. Thus, these accumulations of palmitoylcarnitine groups in mitochondria may increase the catalytic action of CPT.

Theophylline-induced changes in the activity of carnitine palmitoyltransferase in rat cardiac tissues

This study is conducted to investigate the influence of oral theophylline administration (100 mg/kg bw per day) on the activity of carnitine palmitoyltransferase (CPT) in cardiac tissues of rats for 5-week interval treatments. Results showed significant increase in the activity of CPT was observed in cardiac tissues of theophylline-treated groups as compared to either control or placebo groups. Moreover, the results showed positive correlations between the cardiac concentrations of long-chain acylcarnitine (LC) and the activity of CPT and between plasma concentrations of LC and the cardiac concentrations of LC (P<0.01), respectively. The observed changes in activity of cardiac CPT might be due to the result from theophylline- enhanced decrease the sensitivity of CPT to inhibition by malonyl-CoA and/or from theophylline-enhanced mobilization of lipid from adipose tissues which consequently stimulated an increased carnitine transport into the tissues to form palmitoylcarnitine groups for subsequent beta-oxidation inside the mitochondria. Thus, these accumulations of acylcarnitine groups in mitochondria may increase the catalytic action of CPT.

Therapeutic drug monitoring in drug overdose

The treatment of poisoned patients is still largely defined by history, clinical assessment and interpretation of ancillary investigations. Measurement of drug concentrations is clinically important for relatively few compounds. Most measurements form an adjunct to and should not be considered a substitute for clinical assessment. Drug concentrations are particularly important for those compounds where the concentration is predictive of serious toxicity in an otherwise asymptomatic patient.

Study of the effects of theophylline-related changes in total, free, short- chain acyl and long-chain acyl carnitine concentrations in rat heart

This study is conducted to investigate the effect of oral theophylline administration on total (TC), free (FC), short-(SC), long-chain acyl (LC), acyl (AC) carnitine concentrations and acyl to free carnitine (AC/FC) ratio in rat heart. Theophylline was administrated at 100 mg/kg wt/day, and effects were monitored after a treatment period that lasted between a week and five weeks. The results indicated that theophylline feeding leads to significantly higher concentrations of TC, FC, SC, LC and AC in heart tissue as compared to those of control and placebo groups (P < 0.001). Moreover, the ratio of AC/FC was significantly increased (P < 0.001) as compared to either control or placebo groups. These changes may result from theophylline-enhanced mobilization of lipids from adipose tissues, which consequently stimulates an increased carnitine transport into the heart tissues to form fatty acylcarnitines for subsequent beta-oxidation inside the heart mitochondria.

Poisoning and drug overdose

Poisoning is a common cause for intensive care unit admission for both children and adults, and most poisoning victims are effectively treated using standard decontamination measures and supportive care. For a small number of poisons, acceleration of toxin removal with hemodialysis or hemofiltration is indicated. Similarly, specific antidotes are indicated in a few selected circumstances. Rarely, patients may benefit from more aggressive supportive techniques such as cardiopulmonary bypass.

Multiple-dose activated charcoal: a review of relevant clinical studies

Although many studies in animals and volunteers have demonstrated that multiple-dose activated charcoal increases drug elimination significantly, this therapy has not been shown in a controlled study in poisoned patients to reduce morbidity and mortality. Further clinical studies are required to establish its role and the optimum dosage regimen of charcoal to be administered. Based on current evidence, multiple-dose activated charcoal should only be considered if a patient has ingested a life-threatening amount of phenobarbital (phenobarbitone), carbamazepine, theophylline, quinine, dapsone or salicylate. In all of these cases there are data to confirm enhanced elimination, though no controlled studies have demonstrated clinical benefit.

Theophylline toxicity

Theophylline toxicity continues to be a commonly encountered clinical problem. Patients may present with a vast array of toxic manifestations, including life-threatening cardiovascular and neurologic toxicity. Despite the considerable attention this topic has received in the literature, there remain some important controversies regarding the identification of high risk patients and how best to manage them. This review attempts to summarize the current state of knowledge regarding theophylline toxicity with special emphasis on toxic manifestations and the role of elimination enhancing modalities.

Theophylline Toxicokinetics

Toxicokinetics, the application of pharmacokinetic principles in the assessment and management of the poisoned patient, is demonstrated for theophylline poisonings. Theophylline intoxication and its treatment is briefly reviewed and differentiated for acute or chronic etiologies. A toxicokinetic strategy for the simple calculation and evaluation of serum theophylline concentrations following sustained-release products overdosage is presented. A toxicokinetic basis for treatment durations of activated charcoal, hemoperfusion, or hemodialysis is described. Common toxicokinetic factors responsible for presentation with chronic theophylline intoxication are mentioned.

Fatal theophylline poisoning with rhabdomyolysis. A potential role for dantrolene treatment

A fatal case of theophylline poisoning is described. The patient developed rhabdomyolysis, renal failure and compartment syndrome, as well as the more usual features of severe theophylline poisoning. Dantrolene appeared to be useful in controlling the hypermetabolic state associated with the overdose and may have a role in future treatment.

Theophylline poisoning--a review of 64 cases

Sixty-four cases of theophylline poisoning were reviewed. All but two cases represented international self poisoning. The majority of patients were young females who presented acutely after ingestion of sustained release preparations prescribed for asthma. Serum theophylline levels (mean 365 mumol/l, SD 177) indicated a high risk of toxicity. Electrolyte and metabolic abnormalities (hypokalaemia, hypomagnesaemia, hypophosphataemia, hyperglycaemia, acid-base disturbances and leucocytosis) were common. Serum potassium, serum glucose, leucocyte count and length of stay in the intensive care unit all correlated strongly with maximum serum theophylline level (p less than 0.001). The low incidence of life-threatening manifestations of severe toxicity (hypotension, serious arrhythmias or seizures) and excellent outcome, contrasts with many previous reports. The results support the use of a management regimen which emphasizes intensive supportive therapy and restricts the use of charcoal haemoperfusion.

The assessment and treatment of theophylline poisoning

Theophylline poisoning long has been recognized as difficult to treat and still has an over-all mortality rate of about 10%. In recent years, the increasing use of sustained-release preparations has changed the pattern of toxicity. The management of theophylline toxicity is compounded by clinical differences between chronic (overmedication) intoxication and acute single ingestions of a large amount of the drug, inter- and intraindividual variability in theophylline metabolism and dose-dependent kinetics in poisoned patients. Management decisions should be based on both clinical assessment and laboratory information (particularly theophylline concentrations).

Methylxanthines: toxicity to humans. 1. Theophylline

While there are several comprehensive reviews on the toxic effects of theophylline, caffeine and theobromine in animals, data on the toxicity of these methylxanthines in humans have not been extensively reviewed in one document. This question will be addressed in a series of three papers. This paper provides an overview of the human toxicity of theophylline. Only pertinent and recent information on theophylline toxicity is summarized. In addition, some information regarding the use and benefits of theophylline, the mechanism of its effects and factors that affect variability in its clearance and half-life is also provided. Some problems in the analytical methodology of theophylline, problems that may be responsible for the controversy in the reported dose-response effects, are critically reviewed.

Hypokalemia in acute theophylline poisoning

The frequency, severity, and time of occurrence of hypokalemia and their relationship with vomiting was studied in 40 patients with acute theophylline poisoning. The mean peak theophylline concentration was 58 micrograms/mL (range, 21 to 115), and the mean nadir of serum potassium was 3.0 mEq/L (range, 2.1 to 3.9). In 85% of the patients, the nadir of serum potassium was less than 3.5 mEq/L; 45% had potassium concentrations of less than 3 mEq/L. The severity of hypokalemia correlated with peak serum theophylline concentrations (p less than 0.001). Hypokalemia was observed early in the course of the overdose (mean, 5 hours after ingestion or administration of theophylline). The nadir in serum potassium concentrations was more severe among 25 patients who presented to the emergency department within 6 hours of the overdose than among 13 patients who presented later (mean +/- SE, 3.0 +/- 0.1 mEq/L vs 3.4 +/- 0.1 mEq/L, p less than 0.01), despite similar admission serum theophylline concentrations in both groups (49 +/- 5 and 55 +/- 5 micrograms/mL, respectively; p = not significant). Spontaneous or ipecac-induced emesis occurred in 95% of the patients; however, hypokalemia preceded vomiting in 13 patients. Its severity was similar whether patients did or did not vomit before its occurrence. Hypokalemia is a frequent manifestation of acute theophylline poisoning, has a very early onset, and occurs independently of vomiting, suggesting an intracellular shift of potassium.

Evaluation of theophylline overdoses and toxicities

Patients presenting with elevated theophylline concentrations and manifestations of toxicity may be categorized as being either overdose or iatrogenic toxic. In addition to severe cardiac and neurologic toxicities, such as arrhythmias and seizures, OD patients probably require monitoring for manifestation of gastrointestinal hemorrhage, electrolyte abnormalities, and hypotension. The possibility of a delayed peak theophylline concentration after sustained release product ingestion must be considered. Patients with initial serum concentrations of less than 60 mg/L may receive a single dose of oral activated charcoal and have repeat concentrations drawn to ensure the avoidance of continued absorption. The presence of a serum concentration exceeding 60 mg/L in OD patients warrants initiation of elimination-enhancing modalities. Oral activated charcoal is the fastest and most readily available. Multiple-dose oral activated charcoal should be given until serum theophylline concentrations of 60 mg/L or less are reached. Cardiac monitoring and seizure precautions are recommended. Admission to the intensive care unit should be considered when serum concentrations do not decline after several hours of charcoal therapy or when seizures and severe cardiovascular manifestations occur. Patients having initial concentrations exceeding 100 mg/L and/or rapidly rising concentrations 100 mg/L over baseline values should be considered as candidates for CHP or RHP if available. If both CHP and RHP are unavailable or will be excessively delayed, HD is a reasonable alternative. Patients on chronic theophylline therapy (IA patients) presenting with symptoms of toxicity must be evaluated carefully. If serum concentrations are less than 20 mg/L, short-term observation or a reduction in dose should be sufficient. Patients with concentrations between 20 and 60 mg/L should be candidates for seizure precautions and cardiac monitoring. Oral activated charcoal may be started and continued until levels are below 20 mg/mL. Patients with concentrations in excess of 60 mg/L require intensive monitoring (including seizure precautions and cardiac monitoring) as well as initiation of MOAC or CHP/RHP as situation, availability, and patient tolerance dictate. Again, HD may be a reasonable alternative if the others are unavailable or contraindicated.

Hemolysis following treatment of theophylline overdose with coated charcoal hemoperfusion

Life-threatening theophylline toxicity is an indication for coated charcoal hemoperfusion. This can usually be accomplished without serious side effects. We describe here a case of acute severe intravascular hemolysis following coated charcoal hemoperfusion.

Phenobarbital improves survival in theophylline-intoxicated rabbits

As in humans, theophylline intoxication in rabbits causes seizures and death. We studied whether the administration of phenobarbital or phenytoin following a toxic dose of theophylline would improve survival in rabbits. New Zealand white rabbits were infused intravenously with theophylline, 115 mg/kg over 50 minutes. Upon completion of the infusion, rabbits were randomized to receive either saline (control) (N = 60) or saline containing phenobarbital 20 mg/kg (N = 60), or phenytoin 12 mg/kg (N = 30), infused over 30 minutes. The number (and percentage) of rabbits surviving 24 hours in each group was: control 12 (20%), phenobarbital 30 (50%), and phenytoin 7 (23%) [X2; p less than 0.005; two-tailed]. In all fatal cases, death was preceded by a seizure; rabbits that survived did not seize. These results show that phenobarbital administered intravenously to theophylline-intoxicated rabbits prevented seizures and improved survival whereas phenytoin administration had no significant effect.