Nuelin SR 125/Nuelin SR 250 Overdosage

(See Adverse Reactions for possible drug effects that may be seen in overdosage.)
Symptoms: Early symptoms of toxicity such as anorexia, nausea, vomiting, headache, irritability, agitation, anxiety, insomnia, hypotension, palpitations and tachycardia, may progress to sensory disturbances, confusion, hyperthermia, ventricular arrhythmias, extreme thirst, delirium and convulsions.
Every theophylline overdose should be regarded as potentially fatal and all patients should be closely monitored.
Treatment: There is no specific antidote to theophylline. Symptomatic support is indicated. Gastric lavage and general supportive measures (eg to maintain circulation, respiration and fluid and electrolyte balance) are recommended. Oral activated charcoal may reduce serum theophylline levels, whilst in severe cases charcoal haemoperfusion may be required.
The important features of overdose management are: Gastric Decontamination: Gastric lavage is recommended especially when slow release preparations have been ingested. Note that the conscious state, gag reflex or occurrence of seizures may require the patient to be intubated before lavage is carried out. (Ipecac-induced emesis is not appropriate because it reduces the likelihood that patients will be able to tolerate oral charcoal.)
Use of Activated Charcoal and Cathartic (either sorbitol or polyethylene glycol): This has been shown in several studies to reduce the half-life of theophylline substantially, even when absorption has been completed. The recommended dose is 1 g/kg every 4-6 hours (or 10 g/ hour) until the theophylline level has plateaued or commenced falling or is below 55 μmol/L. (This depends on the experience of the physician in managing theophylline overdose.)
Control of Emesis (otherwise patients will not tolerate charcoal): Metoclopramide, ranitidine, droperidol and possibly ondansetron can be used but there is no controlled trial evidence for any of these.
Theophylline Monitoring (see also Precautions): If side effects appear or if unusually high doses are required, serum theophylline should be monitored. Blood samples for monitoring should be drawn immediately before administration of the morning dose when the serum theophylline level is lowest.
Another sample should be drawn 5-10 hours after administration of Nuelin SR when the theophylline level is at a maximum.