Hemodialysis of theophylline in uremic patients

Asymptomatic Theophylline Overdose

A case of severe theophylline overdose is described in which clinical signs of toxicity initially were minimal despite extremely high serum drug levels. Hemodialysis was performed because of the risk of seizures and cardiac arrhythmias. The predialysis, dialysis, and postdialysis half-lives were 13.1, 4.3, and 6.7 hours, respectively. Corresponding total body clearance values were 23.8, 72.5, and 46.3 ml/kg/h. The patient showed apparent saturation kinetics of theophylline clearance at high serum levels. Hemodialysis is effective for enhancing the removal of 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.

Use of the molecular adsorbent recirculating system (MARS™) for the management of acute poisoning with or without liver failure

INTRODUCTION

There is an increasing interest in recent developments in bioartificial and non-bioartificial devices, so called extracorporeal liver assist devices, which are now used widely not only to increase drug elimination, but also to enhance the removal of endogenous substances in acute liver failure. Most of the non-bioartificial techniques are based on the principle of albumin dialysis. The objective is to remove albumin-bound substances that could play a role in the pathophysiology of acute liver failure by dialysing blood against an albumin-containing solution across a high flux permeable membrane. The most widely used device is the Molecular Adsorbent Recirculating System (MARS™).

METHODS

The relevant English and French literature was identified through Medline using the terms, 'molecular adsorbent recirculating system', 'MARS', 'acute liver failure', 'acute poisoning', 'intoxication'. This search identified 139 papers of which 48 reported on a toxic cause for the use of MARS™. Of these 48 papers, 39 specified the substance (eighteen different substances were identified); two papers reported on the same group of patients. BIOARTIFICIAL AND NON-BIOARTIFICIAL SYSTEMS: Bioartificial systems based on porcine hepatocytes incorporated in the extracorporeal circuit are no longer in use due to the possibility of porcine retroviral transmission to humans. Historically, experience with such devices was limited to a few cases of paracetamol poisoning. In contrast, an abundant literature exists for the non-bioartificial systems based on albumin dialysis. The MARS™ has been used more widely than other techniques, such as the one using fractionated plasma separation and adsorption (Prometheus™). All the extracorporeal liver assist devices are able to some extent to remove biological substances (ammonia, urea, creatinine, bilirubin, bile acids, amino acids, cytokines, vasoactive agents) but the real impact on the patient's clinical course has still to be determined. Improvement in cardiovascular or neurological dysfunction has been shown both in acute liver failure and acute-on-chronic liver failure but no impact on mortality has been reported. ACUTE POISONING WITH LIVER FAILURE: Randomized controlled trials are very limited in number and patients poisoned by paracetamol or Amanita phalloides are usually included for outcome analysis in larger groups of acute liver failure patients. Initial results look promising but should be confirmed. Beyond its effect in liver failure, MARS™ could also enhance the elimination of the drug or toxin responsible for the failure, as is described with paracetamol. ACUTE POISONING WITHOUT LIVER FAILURE: Extracorporeal liver assist devices have also been used to promote elimination of drugs that are highly protein bound. Data in various case reports confirm a high elimination of phenytoin, theophylline and diltiazem. However, definite conclusions on the toxicokinetic or clinical efficacy cannot be drawn.

CONCLUSIONS

Despite the lack of large multicentre randomized trials on the use of MARS™ in patients with acute liver failure, the literature shows clinical and biological benefit from this technique. In drug or toxin-induced acute liver failure, such as paracetamol or mushroom poisoning, MARS™ has been used extensively, confirming in a non-randomized fashion, the positive effect observed in the larger population of acute liver failure patients. Furthermore, as MARS™ has been shown in experimental studies to remove protein-bound substances, it is potentially a promising treatment for patients with acute poisoning from drugs that have high protein-binding capacity and are metabolized by the liver, especially, if they develop liver failure concomitantly.

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.

Charcoal hemoperfusion for theophylline overdose: case report and proposal for predicting treatment time

Charcoal hemoperfusion is effective in the treatment of theophylline overdose. Estimation of the time required for charcoal hemoperfusion has been based on personal experience and judgment. We used pharmacokinetic data from a patient and from case reports to generate a formula for predicting treatment time. Pharmacokinetic parameters were calculated using model-independent analysis of concentration-time curves from two treatments of charcoal hemoperfusion. These values were compared with published data and incorporated into a formula that was derived from the elimination rate constant to estimate treatment time of charcoal hemoperfusion: Time (min) = (ln conci-ln concd)/0.0057, where the concentration of theophylline is in mumol/L. The formula may be valid in patients in whom the serum theophylline concentration is less than or equal to 516 mumol/L or 92 mg/L. It may be used as a guide to estimate the length of charcoal hemoperfusion in the treatment of theophylline toxicity. Its validation requires implementation and evaluation in future cases.

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.

Clearance of theophylline by hemodialysis in one patient with chronic renal failure

The clearance of theophylline by hemodialysis was determined in one patient who had polycystic kidney with chronic renal failure and bronchial asthma. The serum levels of theophylline were determined by enzymatic immunoassay on two consecutive days, once on a dialysis day and again on a nondialysis day. Clearance of theophylline by hemodialysis was 119 ml/min, and the extraction efficiency was 0.56. The elimination half-life of theophylline shortened from 5.7 h to 1.6 h during hemodialysis. The dialysis rate constant (Kd) was 0.32/h, and 79 percent of the total body store of the drug was removed during a 4-h dialysis. Patients receiving theophylline who are maintained on hemodialysis should be closely monitored for bronchospasm during and after the hemodialysis procedure. Measurement of serum concentrations of theophylline should be employed to facilitate increases in dosage during hemodialysis.

Pharmacokinetics of cefprozil in healthy subjects and patients with renal impairment

Cefprozil, a new broad-spectrum oral cephalosporin, is composed of cis and trans isomers in an approximate 90:10 ratio. The pharmacokinetics of a single oral 1000-mg dose of cefprozil were evaluated in 6 healthy subjects and 24 patients with various degrees of renal impairment. Six of these subjects were studied both while receiving hemodialysis and during an interdialytic period. Plasma, urine, and hemodialysate that were collected at predetermined times were analyzed for concentrations of the cis and trans isomers of cefprozil using reverse-phase HPLC assay with UV detection. The maximum plasma concentration of the cis isomer ranged from 12.3 micrograms/mL in subjects with normal renal function to 36.7 micrograms/mL in hemodialysis patients. Similarly the area under the plasma concentration-time curve and the elimination half-life increased from 46 micrograms.h/mL to 373 micrograms.h/mL and from 1.72 hours to 5.94 hours, respectively. Renal clearance of the cis isomer decreased from 198 mL/min in normal subjects to 19 mL/min in volunteers with creatinine clearances of less than or equal to 30 mL/min; there was a strong correlation (r2 greater than or equal to .93) between the renal clearance of the cis isomer and creatinine clearance. Urinary recovery of the cis isomer decreased from 57% in those with normal renal function to 24% in the group with a creatinine clearance of less than or equal to 30 mL/min. Hemodialysis decreased the half-life of the cis isomer to 2 hours and removed approximately 55% of it from the body during a 3-hour dialysis period (hemodialysis clearance equaled approximately 87 mL/min). The pharmacokinetics of the trans isomer were similar to those observed for the cis isomer and were affected similarly by declining renal function. A reduction in dosage is recommended in patients with a creatinine clearance of 30 mL/min or less. It may be necessary to administer a dose after hemodialysis to maintain therapeutic plasma 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.

Fatal overdose from a sustained-release theophylline preparation

A 26-year-old woman ingested approximately 9 g of theophylline (Theodur). She exhibited agitation, generalized seizures, hyperglycemia, hypokalemia, hypomagnesemia, hypophosphatemia, and diuresis. Later in her hospital course rhabdomyolysis, myoglobinuria, and acute renal failure occurred. Hemodialysis was performed to correct electrolyte imbalance. She subsequently died of intractable shock and hyperkalemia. This case illustrates the metabolic abnormalities which may occur with severe theophylline intoxication.

Severe theophylline toxicity. Role of conservative measures, antiarrhythmic agents, and charcoal hemoperfusion

The presenting symptoms, course, and treatment of 10 patients with severe theophylline toxicity (heart rate above 120, multifocal atrial tachycardia or premature ventricular contractions, hypotension, seizures) are described. Theophylline levels at presentation averaged 66 micrograms/ml (range 30 to 180 micrograms/ml). All patients had marked tachycardia; 80 percent had gastrointestinal symptoms, 50 percent were hypotensive, and 20 percent had seizures. A known history of poor compliance or other risk factors to overdosage was present in 60 percent. Of the five patients in whom drug clearances were determined, two had uniform first-order drug elimination. Three had biphasic elimination with an initial period of delayed elimination due to either zero-order kinetics or continued drug absorption. During the first-order elimination period, mean plasma theophylline clearance was 28.0 +/- 4.3 ml per minute with a half-life of 8.2 hours. In the patients with initially delayed elimination, the mean clearance during the slow phase was 9.6 +/- 3.3 ml per minute with an apparent half-life of 31 hours. One patient was treated with charcoal hemoperfusion but the others received conservative management alone; all recovered without permanent sequelae. Propranolol and verapamil were useful in controlling supraventricular tachycardia. It appears that most patients with severe theophylline toxicity can be managed without hemoperfusion, which should be considered only when drug clearance is reduced, and hypotension, tachycardia, ventricular ectopy, or seizures are refractory to conservative measures.

Drug prescribing in renal failure: dosing guidelines for adults

The data base for rational guidelines to safe, efficacious drug prescribing in adults with renal insufficiency are presented in tabular form. Current medical literature was extensively surveyed to provide as much specific information as possible. When information is lacking, however, recommendations are based on pharmacokinetic variables in normal subjects. Nephrotoxicity, important adverse effects, and special considerations in renal patients are noted. Adjustments are suggested for hemodialysis and peritoneal dialysis when appropriate.

Effects of hemodialysis on theophylline kinetics

Difficulties encountered in controlling theophylline blood concentrations in an asthmatic patient on hemodialysis prompted us to study the effect of hemodialysis on theophylline kinetics. Plasma theophylline extraction ratios, clearances, and half-lives were determined during dialysis for 11 adults given an intravenous infusion of 4 mg/kg aminophylline. For comparison, eight of these patients were evaluated for theophylline half-lives when not dialyzed. Extraction ratios of theophylline during dialysis ranged from 0.22 to 0.51 (0.35 +/- 0.08) for these patients, indicating that a mean of 36 per cent plasma theophylline was removed during each pass through the dialyzer. This compares with a mean extraction ratio of urea of 0.63 +/- 0.07. Plasma clearance of theophylline during dialysis ranged from 52 to 124 ml/min (83 +/ 20 ml/min). Plasma theophylline half-lives during dialysis ranged from 1.6 to 3.4 hours (2.3 +/- 0.5 hours). Theophylline half-lives when not on dialysis ranged from 3.5 to 8.2 hours (5.0 +/- 1.7). Theophylline clearance was significantly faster in every patient during dialysis. Asthmatics requiring hemodialysis should receive additional theophylline during dialysis if therapeutic blood levels are to be maintained. Routine hemodialysis will significantly increase clearance in a toxic patient in whom life-threatening toxicity is occurring and charcoal hemoperfusion is unavailable.

Comparative pharmacokinetics of theophylline in peritoneal dialysis and hemodialysis

Dialysis clearance and drug recovery of theophylline were investigated in three peritoneal dialysis patients and the results were compared with those obtained from five hemodialysis patients. Peritoneal clearance averaged 9.5 ml/min, in contrast with the hemodialysis clearance of 84.8 ml/min, indicating a relative inefficiency of peritoneal dialysis with regard to theophylline removal. Theophylline half-life was reduced substantially during hemodialysis, 2.0 to 3.2 hours, in comparison with the normal half-life range of 4.7 to 6.8 hours during peritoneal dialysis. The fraction of theophylline recovered by peritoneal dialysis approximated 3.2 per cent of dose, while hemodialysis recovered up to 40 per cent of the administered dose. The overall observations of half-life, dialysis clearance, and drug recovery suggest a clear advantage of hemodialysis over peritoneal dialysis for theophylline detoxification. However, peritoneal dialysis may be preferred to hemodialysis for uremic patients requiring theophylline therapy. Since the removal of theophylline by peritoneal dialysis is minimal, an undesirable alteration of the theophylline dosage regimen in association with dialysis therapy can thus be avoided.

The assessment of fractional drug removal by extracorporeal dialysis

It is generally concurred that the effectiveness of extracorporeal dialysis is best evaluated by fractional drug removal, i.e. the proportion of body burden of drug removed during the period of dialysis treatment. Two equations reported in the literature and five equations proposed in this article are examined for their validity in the assessment of fractional drug removal. Potential limitations and applicable conditions of these equations are discussed and compared. Calculations of fractional drug removal are demonstrated using both simulated and experimental data of ethambutol. Depending on the available kinetic measurements during dialysis and post dialysis, one may apply each equation separately or in conjunction with others to the calculation of fractional drug removal.

Theophylline absorption by effervescent activated charcoal (Medicoal)

Plasma theophylline concentrations were measured in six volunteers given 675 mg of a sustained-release preparation (Phyllocontin). Significant reductions in both the mean recorded peak theophylline plasma concentrations and the mean 12-hour theophylline bioavailability were observed after the administration of effervescent activated charcoal (Medicoal) in single and multiple doses. These results indicate the potential use of activated charcoal in the management of theophylline poisoning.