Role of extracorporeal drug removal in acute theophylline poisoning. A review

Extracorporeal Treatment in the Management of Acute Poisoning: What an Intensivist Should Know?

Extracorporeal treatment (ECTR) represents a treatment modality promoting removal of endogenous or exogenous poisons and supporting or temporarily replacing a vital organ. This article aims to provide a brief overview of the technical aspects and the potential indications and limitations of the different ECTRs, highlighting the important characteristics of poison amenable to ECTR and the most appropriate prescriptions used in the setting of acute poisoning. The various principles that govern poison elimination by ECTR (diffusion, convection, adsorption, and centrifugation) and how components of the ECTR can be adjusted to maximize clearance have also being discussed.

Pharmacological potential of methylxanthines: Retrospective analysis and future expectations

Methylated xanthines (methylxanthines) are available from a significant number of different botanical species. They are ordinarily included in daily diet, in many extremely common beverages and foods. Caffeine, theophylline and theobromine are the main methylxanthines available from natural sources. The supposedly relatively low toxicity of methylxanthines, combined with the many beneficial effects that have been attributed to these compounds through time, generated a justified attention and a very prolific ground for dedicated scientific reports. Methylxanthines have been widely used as therapeutical tools, in an intriguing range of medicinal scopes. In fact, methylxanthines have been/were medically used as Central Nervous System stimulants, bronchodilators, coronary dilators, diuretics and anti-cancer adjuvant treatments. Other than these applications, methylxanthines have also been hinted to hold other beneficial health effects, namely regarding neurodegenerative diseases, cardioprotection, diabetes and fertility. However, it seems now consensual that toxicity concerns related to methylxanthine consumption and/or therapeutic use should not be dismissed. Taking all the knowledge and expectations on the potential of methylxanthines into account, we propose a systematic look at the past and future of methylxanthine pharmacologic applications, discussing all the promise and anticipating possible constraints. Anyways, methylxanthines will still substantiate considerable meaningful research and discussion for years to come.

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.

A case of fatal caffeine poisoning

Caffeine is a natural alkaloid methylxanthine that is found in various plants such as coffee or tea. Symptoms of a severe overdose may present with hypokalemia, hyponatremia, ventricular arrhythmias, hypertension followed by hypotension, respiratory failure, seizures, rhabdomyolysis, ventricular fibrillation and finally circulatory collapse. A 21-year-old woman called for the ambulance herself soon after the ingestion of about 10,000 mg of caffeine. At the arrival of the ambulance, the patient went into cardiac arrest almost immediately. After a total resuscitation period of 34 min including seven counter-shocks and 2 mg epinephrine, the patient was stable enough to be transferred to the hospital. The patient soon went into VF again and received two more counter-shocks and 1 mg epinephrine and finally an intravenous bolus dose of 300 mg amiodarone. The initial arterial blood gas showed pH at 6.47, lactate at 33 mmol/l and potassium level at 2.3 mmol/l. Unfortunately, no blood samples for caffeine analysis were taken. Three days after hospital admission, the patient developed myoclonus, which did not respond to medical treatment. Excessive intake of caffeine may produce arrhythmias and pronounced hypokalemia and ensuing ventricular fibrillation. In case of counter-shock-resistant VF, it can be necessary to give an early loading dose of amiodarone. Furthermore, it may be beneficial to replace the potassium as early as possible. Epinephrine and buffer solutions used during resuscitation may further decrease blood potassium levels and should be administrated cautiously. Epinephrine can be replaced by other vasopressor drugs, such as vasopressin without effects on beta-receptors.

Comparative efficacy of hemodialysis and hemoperfusion in severe theophylline intoxication

OBJECTIVE

To determine the comparative efficacy of hemoperfusion and hemodialysis for severe theophylline toxicity in concurrent case series.

METHODS

A 10-year, prospective, observational study was performed of consecutive patients referred to a regional poison control center with severe theophylline intoxication in whom either hemodialysis or hemoperfusion was used. The primary outcomes were 1) incidence of major theophylline toxicity (convulsions or life-threatening cardiac dysrhythmias) during or after each procedure, 2) calculated theophylline clearance, and 3) procedure-related complications.

RESULTS

Over the study period, 56 patients underwent hemodialysis or hemoperfusion as treatment of severe theophylline intoxication. Overall mean age was 40.5 +/- 22.9 years. Mean peak serum theophylline concentration was 103.3 +/- 39.1 micrograms/mL (range 36 to 245 micrograms/mL). Thirty patients (54%) were victims of acute theophylline intoxication, while 18 (32%) had chronic overmedication and 8 (14%) had acute-on-therapeutic intoxication. Thirty-nine patients (70%) underwent hemodialysis, while 17 (30%) underwent hemoperfusion. There were no significant intergroup differences in age (39.4 vs 43.0 yr), peak serum theophylline concentration (99.5 vs 112.1 micrograms/mL), time to procedure (8.4 vs 6.3 hr), or duration of procedure (4.1 vs 3.7 hr). Thirty-three percent of the patients undergoing hemodialysis had major toxicity during or after the procedure, compared with 18% of those who received hemoperfusion (p = NS). Post-procedure serum theophylline concentrations were 26.9 vs 30.4 micrograms/mL, corresponding to drug clearance rates of 185.1 and 294.8 mL/kg/hr (p = 0.03). Procedural complications occurred in 3 patients who received hemoperfusion and consisted of bleeding diatheses and hypocalcemia. No complications occurred in patients receiving hemodialysis (p = 0.007).

CONCLUSIONS

These data confirm that hemoperfusion provides a higher theophylline clearance rate than hemodialysis. However, hemodialysis appears to have comparable efficacy in reducing the morbidity of severe theophylline intoxication and is associated with a lower rate of procedural complications.

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.

Whole-bowel irrigation as adjunctive treatment for sustained-release theophylline overdose

STUDY OBJECTIVE

To determine a therapeutic benefit for whole-bowel irrigation (with polyethylene glycol-electrolyte lavage solution) as adjunctive treatment to multiple doses of activated charcoal following an overdose of sustained-release theophylline.

DESIGN

Randomized crossover study. Three treatment arms were separated by one-week intervals.

SETTING

Animal care facility housing.

TYPE OF PARTICIPANTS

Eight female mongrel dogs.

INTERVENTIONS

Unanesthetized dogs were given approximately 75 mg/kg of sustained-release theophylline. In treatment arm 1, 1 g/kg activated charcoal was administered by nasogastric tube at two hours after ingestion followed by 0.5-g/kg doses at five and eight hours. During treatment arm 2, beginning two hours after theophylline ingestion, 25 mL/kg whole-bowel irrigation solution was administered every 45 minutes for four doses followed by activated charcoal. In treatment arm 3, the first dose of activated charcoal was given ten minutes before beginning the whole-bowel irrigation protocol.

MEASUREMENTS AND MAIN RESULTS

Serum theophylline levels were measured at zero, two, four, five, eight, 12, 16, and 24 hours after ingestion. Mean serum theophylline levels, area under the curve (P = .13), and terminal half-lives (P = .69) for each treatment group were not statistically different. This negative study had an 81% power to detect a 50% reduction in the area under the curve by whole-bowel irrigation treatment.

CONCLUSION

In this model, whole-bowel irrigation did not add to the therapeutic benefits of activated charcoal.

Effect of acute versus chronic intoxication on clinical features of theophylline poisoning in children

OBJECTIVES

To determine whether the method of intoxication influences the metabolic disturbances and pattern of life-threatening events that occur after theophylline intoxication in children.

METHODS

Five-year prospective observational study of consecutive pediatric patients referred to a regional poison control center with a theophylline concentration (theo) greater than or equal to 30 micrograms/ml. At the time of referral, intoxication was categorized as acute (single toxic exposure), chronic (long-term toxic exposure), or acute-on-therapeutic (single toxic exposure superimposed on maintenance therapy).

RESULTS

One-hundred twenty-five patients were monitored. Mean age was 12 years (range, 3 days to 20 y). Seventy-four patients (59%) had acute intoxication, 31 (25%) had chronic intoxication, and 20 (16%) had acute-on-therapeutic intoxication. Mean peak serum (theo) was 55 micrograms/ml. Life-threatening events occurred in 12 patients (10%). Patients with acute intoxication had a significantly lower serum potassium level (3.04 vs 3.80 mmol/L; p less than 0.001) and higher serum glucose level (10.8 vs 7.0 mmol/L (194 vs 127 mg/dl); p less than 0.001) than did children with chronic intoxication. Although life-threatening events (seizures or arrhythmias) occurred at a similar rate across categories, the (theo) at which these events occurred was significantly higher in patients with acute intoxication than in those with chronic intoxication (100 vs 42 micrograms/ml; p = 0.02). Among children with chronic intoxication, those who had life-threatening events had (theo) similar to those who remained well (42 vs 47 micrograms/ml) but were significantly younger (1.6 vs 8.0 years; p less than 0.001).

CONCLUSIONS

These data indicate that method of intoxication has significant effects on the metabolic and clinical consequences of theophylline poisoning. Life-threatening events occur in those with acute theophylline intoxication at significantly higher (theo) than in those with chronic intoxication. After chronic intoxication, peak (theo) does not identify patients at risk for life-threatening events; young age appears to be the primary risk factor. These findings potentially complicate the management of theophylline poisoning, given the difficulty of extracorporeal drug removal in young infants.

Pharmacokinetics of theophylline and its metabolites during acute renal failure. A case report

After unsuccessful therapy with salbutamol syrup and inhaled terbutaline a 3-year-old boy with an acute exacerbation of asthma was treated with nebulised salbutamol (albuterol), intravenous aminophylline and hydrocortisone. His condition continued to deteriorate and he required artificial ventilation. Subsequently, he became anuric, with liver dysfunction, nonspecific encephalopathy and limb tremor. Peritoneal dialysis was started. Plasma theophylline concentrations were monitored and maintained in the therapeutic or subtherapeutic range. Despite this, he was hyper-reflexic with limb tremor. Excessively high plasma concentrations of the principal theophylline metabolite, 1,3-dimethyluric acid, were found [maximum 92 mg/L (470 mumol/L)], which cleared only with the return of normal renal function. Plasma concentration monitoring of drugs other than theophylline was not performed. After the patient recovered, a pharmacokinetic study demonstrated that normal methylxanthine metabolism was re-established. Pharmacokinetic analysis indicated that the undue accumulation of the metabolites was a result of an inability to clear these compounds. Thus, pharmacologically and toxicologically active metabolites of theophylline may accumulate in anuric patients on peritoneal dialysis, producing clinical symptoms of toxicity. However, in the present case the possible role of metabolites of other drugs cannot be definitely excluded.