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ISSUE 5 OCTOBER
Letters to the Editor

Medications which may lower seizure threshold

  • Stephanie Pepper

Letter - Stephanie Pepper

Editor, – I would like to offer another explanation for the apparent 'seizure activity' reported by Dr Loadsman (Aust Prescr 2001;24:51-2) when pethidine and tramadol were used concurrently. Both these drugs have serotonin reuptake inhibitor activity and have been implicated in serotonin toxicity when combined with other serotonergic drugs.

Co-administration of pethidine and tramadol could certainly result in a pharmacodynamic interaction, leading to signs and symptoms of excess serotonin in the central nervous system such as 'twitching and anxiety'. These as well as the neuromuscular features, myoclonic spasms, tremor, clonus, hyperreflexia and hypertonia are included in Sternbach's diagnostic criteria for 'serotonin syndrome' and can easily be mistaken for 'seizure activity'. Physicians should be alert to the possibility of serotonin toxicity when pethidine is given to patients who have recently taken, or are still taking, serotonergic drugs (such as selective serotonin reuptake inhibitors and monoamine oxidase inhibitors). Concurrent use of pethidine and tramadol should be undertaken with caution or avoided when possible, because of the risk of serotonin toxicity.

Stephanie Pepper
Drug Information Pharmacist
Hunter Drug Information Service
Newcastle Mater Misericordiae Hospital
Waratah, NSW

 

The Editorial Executive Committee welcomes letters, which should be less than 250 words. Before a decision to publish is made, letters which refer to a published article may be sent to the author for a response. Any letter may be sent to an expert for comment. When letters are published, they are usually accompanied in the same issue by their responses or comments. The Committee screens out discourteous, inaccurate or libellous statements. The letters are sub-edited before publication. Authors are required to declare any conflicts of interest. The Committee's decision on publication is final.

Stephanie Pepper

Drug Information Pharmacist, Hunter Drug Information Service, Newcastle Mater Misericordiae Hospital, Waratah, NSW