Flu-like symptoms associated with fluoxetine overdose: a case report

Cyclic Antidepressant Poisoning: A Review and Case Report

Although newer cyclic antidepressants have been introduced over the past several years, the tricyclic antidepressants (TCAs) continue to be the leading cause of morbidity from drug overdose in the United States. Overdose features depend on the particular cyclic antidepressant ingested and its pharmacological properties, and can include CNS depression, cardiac arrhythmias, hypotension, seizures, and anticholinergic symptomatology. Life-threatening symptomatology almost always begins within 2 hours, and certainly within 6 hours, after arrival to the emergency department. Plasma TCA levels are unreliable predictors of TCA toxicity and are not recommended. An ECG with a prolonged QRS complex more than 100 msec seems to be the best indicator of serious sequelae with TCAs. Management consists of stabilization of vital signs, gastrointestinal decontamination, intravenous sodium bicarbonate, and supportive care. Agents once thought to be useful for the treatment of cardiac dysrhythmias and seizures such as phenytoin and physostigmine should be avoided. The future of TCA antibody fragments in the treatment of TCA overdose seems promising. Newer and, to some degree, safer antidepressants in overdose have recently been introduced, and they include fluoxetine, trazodone, and sertraline. Amoxapine, bupropion, and maprotiline seem to be as toxic as the TCAs. A significant interaction between cyclic antidepressants and monoamine-oxidase inhibitors exists. Management includes supportive care and basic poison management. Prevention of poisoning seems to be the most logical and effective method of maintaining patient safety. TCAs should be avoided in children younger than 6 years old. All adults with suicidal ideations should receive no more than a 1-week supply (about 1 g) of drug. Finally consideration should be given to using one of the newer, safer antidepressants in all patients with suicidal ideations.

Selective serotonin reuptake inhibitor poisoning: An evidence-based consensus guideline for out-of-hospital management

A review of US poison center data for 2004 showed over 48,000 exposures to selective serotonin reuptake inhibitors (SSRIs). A guideline that determines the conditions for emergency department referral and prehospital care could potentially optimize patient outcome, avoid unnecessary emergency department visits, reduce health care costs, and reduce life disruption for patients and caregivers. An evidence-based expert consensus process was used to create the guideline. Relevant articles were abstracted by a trained physician researcher. The first draft of the guideline was created by the lead author. The entire panel discussed and refined the guideline before distribution to secondary reviewers for comment. The panel then made changes based on the secondary review comments. The objective of this guideline is to assist poison center personnel in the appropriate out-of-hospital triage and initial management of patients with a suspected ingestion of an SSRI by 1) describing the process by which an ingestion of an SSRI might be managed, 2) identifying the key decision elements in managing cases of SSRI ingestion, 3) providing clear and practical recommendations that reflect the current state of knowledge, and 4) identifying needs for research. This guideline applies to ingestion of immediate-release forms of SSRIs alone. Co-ingestion of additional substances might require different referral and management recommendations depending on their combined toxicities. This guideline is based on an assessment of current scientific and clinical information. The expert consensus panel recognizes that specific patient care decisions may be at variance with this guideline and are the prerogative of the patient and the health professionals providing care, considering all of the circumstances involved. This guideline does not substitute for clinical judgment. Recommendations are in chronological order of likely clinical use. The grade of recommendation is in parentheses. 1) All patients with suicidal intent, intentional abuse, or in cases in which a malicious intent is suspected (e.g., child abuse or neglect) should be referred to an emergency department. This activity should be guided by local poison center procedures. In general, this should occur regardless of the dose reported (Grade D). 2) Any patient already experiencing any symptoms other than mild effects (mild effects include vomiting, somnolence [lightly sedated and arousable with speaking voice or light touch], mydriasis, or diaphoresis) should be transported to an emergency department. Transportation via ambulance should be considered based on the condition of the patient and the length of time it will take the patient to arrive at the emergency department (Grade D). 3) Asymptomatic patients or those with mild effects (defined above) following isolated unintentional acute SSRI ingestions of up to five times an initial adult therapeutic dose (i.e., citalopram 100 mg, escitalopram 50 mg, fluoxetine 100 mg, fluvoxamine 250 mg, paroxetine 100 mg, sertraline 250 mg) can be observed at home with instructions to call the poison center back if symptoms develop. For patients already on an SSRI, those with ingestion of up to five times their own single therapeutic dose can be observed at home with instructions to call the poison center back if symptoms develop (Grade D). 4) The poison center should consider making follow-up calls during the first 8 hours after ingestion, following its normal procedure. Consideration should be given to the time of day when home observation will take place. Observation during normal sleep hours might not reliably identify the onset of toxicity. Depending on local poison center policy, patients could be referred to an emergency department if the observation would take place during normal sleeping hours of the patient or caretaker (Grade D). 5) Do not induce emesis (Grade C). 6) The use of oral activated charcoal can be considered since the likelihood of SSRI-induced loss of consciousness or seizures is small. However, there are no data to suggest a specific clinical benefit. The routine use of out-of-hospital oral activated charcoal in patients with unintentional SSRI overdose cannot be advocated at this time (Grade C). 7) Use intravenous benzodiazepines for seizures and benzodiazepines and external cooling measures for hyperthermia (>104 degrees F [>40 degrees C]) for SSRI-induced serotonin syndrome. This should be done in consultation with and authorized by EMS medical direction, by a written treatment protocol or policy, or with direct medical oversight (Grade C).

An in vitro evaluation of fluoxetine adsorption by activated charcoal and desorption upon addition of polyethylene glycol-electrolyte lavage solution

BACKGROUND

In drug overdoses, treatment with activated charcoal is frequently used because of its adsorptive properties. Recently, whole-bowel irrigation with polyethylene glycol-electrolyte lavage solution has been used as a gastrointestinal decontamination procedure for ingestions of toxins not well adsorbed to activated charcoal and for toxins with a delayed absorption phase, although well adsorbed to activated charcoal. While a combined approach using activated charcoal and whole-bowel irrigation could theoretically enhance the efficacy of both modalities, this improvement remains speculative, since data demonstrating its clinical advantage in overdose treatment are lacking. Fluoxetine, a selective serotonin uptake inhibitor, is one of the most frequently prescribed antidepressants. Fluoxetine is well adsorbed onto activated charcoal. This in vitro investigation was undertaken to study: a) the effect of polyethylene glycol, as well as polyethylene glycol-electrolyte lavage solution, on the adsorption of fluoxetine to laboratory grade-activated charcoal and a commercial activated charcoal formulation (Carbomix powder) in simulated gastric (pH= 1.2) and intestinal (pH=7.2) fluid environment; b) whether the order of polyethylene glycol-electrolyte lavage solution addition would have any effect on the adsorption of fluoxetine to activated charcoal.

METHODS

Adsorption of fluoxetine to charcoal in the presence of polyethylene glycol was examined: a) by the simultaneous addition of polyethylene glycol and charcoal to fluoxetine solution and b) by the addition of charcoal to fluoxetine solution and subsequent addition of polyethylene glycol. In both cases, the slurries were incubated at 37 degrees C for 1 hour and filtered. Free fluoxetine concentration was determined in the diluted filtrate by a reversed-phase high-performance liquid chromatography method.

RESULTS

The amount of fluoxetine adsorbed to activated charcoal (or Carbomix) was dramatically decreased at gastric and intestinal pH by the presence of polyethylene glycol or polyethylene glycol-electrolyte lavage solution added either concurrently or sequentially to activated charcoal.

CONCLUSIONS

In cases of fluoxetine overdose, administration of activated charcoal is recommended, while a combined approach using activated charcoal and whole-bowel irrigation with polyethylene glycol-electrolyte lavage solution is not recommended since it causes a significant desorption of the drug from activated charcoal.

Antidepressant Poisoning and Treatment: A Review and Case Illustration

Although newer antidepressants have been introduced over the past several years, the tricyclic antidepressants (TCAs) continue to be a leading cause of morbidity from drug overdose in the United States. Overdose features depend on the particular cyclic antidepressant ingested and its pharmacological properties, and can include CNS depression, cardiac dysrhythmias, hypotension, seizures, and anticholinergic symptoms. Life-threatening events almost always begin within two hours, and certainly within six hours, after arrival to the emergency department. Plasma TCA levels are unreliable predictors of TCA toxicity and are therefore not recommended. An ECG with a prolonged QRS complex more than 100 msec seems to be the best indicator of serious sequelae with TCA overdose. Management consists of stabilization of vital signs, gastrointestinal decontamination, intravenous sodium bicarbonate, and supportive care. Agents once thought to be useful for the treatment of cardiac dysrhythmias and seizures such as phenytoin and physostigmine should be avoided. The future of TCA antibody fragments in the treatment of TCA overdose seems promising. Amoxapine, bupropion, and maprotiline seems to be as toxic as the TCAs. Overdose data is limited for venlafaxine, and mirtazapine, and preclude firm conclusions. A significant interaction between cyclic antidepressants and monoamine-oxidase inhibitors exists. Management includes supportive care and basic poison management. Prevention of poisoning seems to be the most logical and effective method of maintaining patient safety. TCAs should be avoided in children younger than 6 years old. All adults with suicidal ideations should receive no more than a one-week supply (less than 1 g) of drug. Newer and, to some degree, safer antidepressants in overdose have recently been introduced, and they include fluoxetine, sertraline, paroxetine, trazodone, and nefazodone. Finally, consideration should be given to using one of these newer, safer antidepressants in all patients with suicidal ideations.

Epidemiology and relative toxicity of antidepressant drugs in overdose

Antidepressant drugs are currently the mainstay of treatment for all but the mildest forms of depression. Their effectiveness in the management of depressive illness is undisputed and their effectiveness in preventing suicide, while not proven, may be assumed. Nevertheless, of all the drugs that are taken in lethal overdose, prescribed antidepressants are among the most common. Epidemiological studies from several countries have provided evidence of marked differences in overdose toxicity between drug classes and, in some cases, between individual drugs within a class, with some of the older tricyclic antidepressants (TCAs) being the most toxic. Over 80% of all deaths arising from overdose of antidepressant medication in the UK between 1987 and 1992 were caused by 2 drugs: amitriptyline and dothiepin. Taken alone, this figure conveys little information about the toxicity of either drug. However, when considered within an epidemiological context, the evidence suggests that both drugs are highly toxic in overdose, a conclusion that is supported by animal studies of the toxicity of TCAs and by clinical evidence of overdose toxicity. This paper reviews the epidemiological evidence concerning the acute toxicity of antidepressant drugs and considers the interplay of factors that contribute to the toxicity which occurs when they are taken in acute overdose. The inherent toxicity of the drug appears to be the crucial factor and, although less well researched, prescribing practices and perception of toxicity are probable contributory factors.

In vitro adsorption study of fluoxetine onto activated charcoal at gastric and intestinal pH using high performance liquid chromatography with fluorescence detector

BACKGROUND

This in vitro investigation was performed to study the adsorption characteristics of fluoxetine to activated charcoal and its commercial formulation Carbomix powder in simulated gastric (pH = 1.2) and intestinal (pH = 7.2) fluid environments.

METHODS

Solutions containing fluoxetine and charcoal were incubated at 37 degrees C for one hour. Reversed phase high performance liquid chromatography was used for the determination of free fluoxetine concentrations (range 0.2-8 micrograms/mL) in the diluted filtrate.

RESULTS

The maximum adsorption capacities at pH 1.2 for activated charcoal and Carbomix were 223 and 333 mg/g, respectively; at pH 7.2 they were 301 and 453 mg/g, respectively. The affinity constant values at pH 1.2 of activated charcoal and Carbomix were 441 and 122 L/g, respectively, while at pH 7.2 they were 482 and 589 L/g, respectively, indicating a strong binding of fluoxetine onto charcoals.

CONCLUSIONS

Relative to the toxic and lethal doses in cases of fluoxetine intoxications, both types of charcoals tested were found effective for adsorption at gastric and intestinal pH. Adsorbed fluoxetine was significantly increased at intestinal pH, consistent with predominant adsorption of the undissociated form of the drug. We conclude that activated charcoal and Carbomix have adsorptive properties appropriate to medical treatment in cases of fluoxetine overdose.

Acute fluoxetine overdose: a report of 234 cases

Limited toxicity information is available in the medical literature on the antidepressant fluoxetine (Prozac, Dista Products Co, Indianapolis, IN). The goal of this prospective multicenter study was to develop a toxicity profile of initial signs and symptoms observed in an acute fluoxetine overdose. A prospective study was made of patients reported to one of four American Association of Poison Control Centers' regional poison control centers after ingesting an acute overdose of fluoxetine. A standard data collection form was used on all patients ingesting fluoxetine. Information obtained included age, current medications, dose, coingested drugs, presenting symptoms, vital signs, electrocardiogram abnormalities, outcome, and fluoxetine levels. The authors collected 272 cases; 234 cases met the criteria of the study. Fluoxetine was ingested alone in 87 cases and with ethanol or other drugs in the remaining 147 cases. Of the 87 cases where fluoxetine was ingested alone, 67 patients were adults and 20 were children. Symptoms that were seen in the adult group included: tachycardia (15/67), drowsiness (14/67), tremor (five/67), vomiting (four/67), or nausea (four/67). Thirty patients did not develop symptoms. Twelve of the adult overdose patients had total fluoxetine levels ranging from 232 to 1390 ng/mL. The authors conclude that symptoms that develop after an acute overdose of fluoxetine appear minor and of short duration. Aggressive supportive care is the only intervention necessary.

The effects of fluoxetine in the overdose patient

Fluoxetine (Prozac) is a new antidepressant, first marketed in the United States in January 1988. Only limited toxicologic information during a fluoxetine overdose is available. The goal of this prospective multi-center study was to develop a toxicity profile of initial signs and symptoms observed in fluoxetine overdose. A standardized data collection form was used on all patients ingesting fluoxetine as reported to four poison centers. Information obtained included age, dose, co-ingested drugs, presenting symptoms, vital signs, EKG abnormalities and lab values. Of the 127 cases of acute fluoxetine overdose collected, 106 cases met the criteria of the study. Of these, 69/106 ingested other drugs, including ethanol and 37/106 ingested fluoxetine alone. Of the latter group, the amounts ingested ranged from 20 to 1500 mg. It was observed that 48.6% (18/37) remained asymptomatic, 16.2% (7/37) were sleepy, 24.3% (9/37) had a sinus tachycardia (of 100 beats per minute or greater), and 8.1% (3/37) had a diastolic pressure over 100 mm Hg. Data collection is ongoing. Based upon our initial experience, fluoxetine in overdose appears to be relatively benign.