Background: Chronic administration of theophylline can be used for treating asthma; it may represent a severe risk when some other drugs are prescribed by unaware physicians.
Case report: A 4 yr-8-mo-old boy was admitted suffering from status epilepticus which occurred 3 hours after vomiting. This patient had asthma and was given sustained-release formulation of theophylline and, independently by another physician, two anti-H1 drugs: ketotifen and mequitazine. Serum theophylline concentration measured 9 hours after the onset of vomiting was 28 micrograms/ml; the calculated concentrations were 45.3 +/- 4, 40.2 +/- 4 and 33.4 +/- 4 micrograms/ml after the last administration of theophylline, the onset of vomiting and the onset of seizures, respectively. The patient was given IV fluids plus clonazepam and recovered completely.
Conclusion: Severe poisoning can be seen with moderately increased blood levels of theophylline when this drug is chronically administered. Association of other drugs such as anti-H1 could represent an additional risk.