Treatment of severe poisoning with slow release theophylline

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.

On-line hemodialysis and hemoperfusion in a girl intoxicated by theophylline

In a suicidal attempt, a 15-year-old girl had ingested about 40 g of theophylline from sustained-release preparations. Symptoms of intoxication increased and serum concentrations of theophylline rose from 438 to 1,000 mumol/l. Conservative therapy was also combined by the use of hemodialysis as well as charcoal hemoperfusion on line. Treatment successfully reduced side-effects and S-theophylline within 12 hours and the patient could leave the hospital without residual sequelae. The combination of hemodialysis and hemoperfusion may reduce the risk of hypopotassiemia and hypocalcemia as well as increase in the clearance of the drug.

Controlled release drugs in overdose. Clinical considerations

The main characteristic of overdose with controlled release formulations is the delay in presentation and onset of clinical effects. There is a prolonged absorption phase which leads to a delayed time to maximum plasma concentration and usually a prolonged time with levels close to the peak concentration. Absorption may continue for more than 24 hours. Overdose with controlled release formulations of toxic drugs therefore requires a longer period of observation as the onset of symptoms may be as late as 16 to 20 hours after ingestion. Treatment nomograms calculated for standard formulations are not appropriate for controlled release formulations. The optimal gastrointestinal decontamination method is controversial, but in serious overdoses it should include gastric lavage and activated charcoal followed by whole bowel irrigation as a means of clearing whole tablets from the gastrointestinal tract. Pharmacobezoar formation should be suspected if, despite apparently effective gastrointestinal decontamination, there is evidence of continuing absorption. These are best diagnosed with endoscopy and the treatment options include endoscopic removal, whole bowel irrigation and surgery.

Efficiency of whole bowel irrigation with and without metoclopramide pretreatment

Whole bowel irrigation (WBI) with a polyethylene glycol electrolyte lavage solution (PEG-ELS) is a gastrointestinal (GI) decontamination procedure used after selected ingestions of toxic substances. The purpose of this study was to evaluate the ability of WBI, with and without metoclopramide pretreatment, to clear the GI tract of foreign bodies using previously established WBI end points, ie, the presence of a clear effluent or the administration of 2 L/h PEG-ELS for 5 hours. Eleven healthy, adult, male volunteers participated in this controlled, two-phase, blinded, crossover study. Ten fluorescent coffee beans were ingested after an overnight fast followed 1 hour later by 10 mg of metoclopramide syrup or an equivalent volume of placebo; 30 minutes later, WBI with PEG-ELS was begun at 2 L/h. All volunteers received 10 L of PEG-ELS during a 5-hour period. No statistically significant difference (P > .05) was found between the two pretreatments. For the metoclopramide group, the mean number of beans passed was equal to 3.8 (+/- 2.5 standard deviation [SD]; 1 to 8 R); the mean number at clear effluent was equal to 2.3. For the placebo group, the mean number of beans passed was equal to 3.5 (+/- 1.9 SD; 2 to 7 R), and the mean number at clear effluent was equal to 2.3. In conclusion, the presence of a clear effluent or the administration of 10 L of PEG-ELS are not valid markers for the termination of WBI if complete elimination of a foreign body is required. Pretreatment with 10 mg of oral metoclopramide does not enhance the efficiency of WBI.

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.

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.

Theophylline toxicity causing rhabdomyolysis and acute compartment syndrome

A case of acute compartment syndrome is described in a young man as a result of theophylline toxicity. Profound hypokalaemia and grand mal seizures are considered as potential causes of rhabdomyolysis and the subsequent development of compartment syndrome.

Adverse reactions and interactions with theophylline

Despite the trend towards newer therapeutic agents, theophylline continues to play a major role in the treatment of reversible airway obstruction. Clinical use of the drug is complicated by a relatively narrow therapeutic range and a large pharmacokinetic variability between patients. Generally, however, theophylline toxicity is foreseeable and preventable. Most cases can be attributed to either inadvertent or intentional overdosing of the drug. Age, disease state and drug interactions are other factors which may contribute to its toxicity. Nausea, vomiting and tachycardia are common signs of mild theophylline toxicity; seizures, ventricular arrhythmias and hypotension are life-threatening manifestations of severe toxicity which may respond poorly to standard therapy. Although serum theophylline concentration correlates with toxicity in a general fashion, life-threatening adverse reactions are not readily predictable from the drug concentration alone. Treatment of theophylline toxicity primarily involves supportive care along with gastric lavage and administration of activated charcoal to facilitate drug removal. The early use of haemoperfusion may be life-saving in cases of severe toxicity.

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).

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.

Guide to therapy with theophylline for the treatment of obstructive lung disease

During the last 10-15 years, therapy with theophylline for the treatment of obstructive lung disease has been rationalized because of increased investigation into drug pharmacokinetics and metabolism and the introduction of new techniques for measuring drug concentration in plasma. Orally administered sustained-release preparations of theophylline have recently been introduced as therapy following the development of new technology. Such preparations allow more effective use of theophylline through increased patient compliance and the maintenance of more stable plasma theophylline concentrations.

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

Theophylline, with its narrow therapeutic margin, is a common cause of iatrogenic and deliberate overdose. Most cases of self-poisoning are with sustained release preparations, with peak concentrations occurring up to 12 or more hours after overdose. Toxic symptoms are often seen at concentrations above 15 mg/L. Theophylline is metabolised within the cytochrome P-450 system, with an average total body clearance of 50 to 60 ml/min. Clearance is, however, affected by many factors such as other drugs or disease, and in overdose zero order kinetics may result in prolonged half-lives. Toxicity is characterised by agitation, tremor, nausea, vomiting, abdominal pains, seizures, and tachyarrhythmias. Hypokalaemia and metabolic acidosis are more profound in acute toxicity, and hypercalcaemia is usually present. Seizures occur at lower concentrations after chronic over-medication than after acute overdose. Gastric lavage should be performed in all patients presenting early, and an oral multiple dose charcoal regimen started with 50 to 100g charcoal, repeating with 50g doses and checking theophylline concentrations at 2- to 4-hour intervals. Multiple dose charcoal can be expected to double the clearance of theophylline, being as effective as a haemodialysis. Of the invasive techniques available, charcoal haemoperfusion is the most effective, increasing clearance 4- to 6-fold. Supportive care is particularly important. The aggressive supplementation of potassium, treatment of emesis with droperidol and ranitidine, and treatment of tachyarrhythmias and hypotension (possibly with propranolol), together with oral multiple dose charcoal may obviate the need for haemoperfusion. Seizures suggest increased morbidity and mortality. Charcoal haemoperfusion should be considered if plasma concentrations are greater than 100 mg/L in an acute intoxication or greater than 60 mg/L in a chronic intoxication. The decision to haemoperfuse should not be based on plasma concentrations alone, but an overall evaluation of the patient's laboratory and clinical status.

Theophylline poisoning. Pharmacological considerations and clinical management

The recent marketing of slow release preparations of theophylline and new indications for the use of the drug have resulted in a marked increase in the sale of theophylline products. This phenomenon combined with the drug's highly variable pharmacokinetics has led to an increase in the number of theophylline intoxications. The morbidity and mortality rates associated with theophylline intoxication are significant. Therefore it is essential that clinicians are aware of the pathophysiology, clinical presentation and treatment of this poisoning. Theophylline intoxication mainly affects the gastrointestinal, cardiovascular and central nervous systems. Signs and symptoms range from mild gastrointestinal upset to serious central nervous system manifestations such as seizures, a symptom often associated with a bad prognosis. Theophylline serum concentrations are very useful for making decisions regarding treatment. However, their interpretation should take into account several factors such as the age of the patient and the type of intoxication (acute versus chronic). Prevention of gastrointestinal absorption should be the principal objective of treatment of an oral theophylline poisoning. The repetitive administration of activated charcoal not only prevents theophylline absorption but also increases its rate of Once absorbed, external methods such as haemodialysis and haemoperfusion can significantly accelerate the elimination of the drug from the body. Finally, the rapid suppression of seizures and cardiac arrhythmias are essential to prevent severe neurological sequelae and death. Since theophylline intoxication can be potentially life-threatening, its administration should be monitored with regular measurements of the serum theophylline concentration, especially in the very young and the very old.