Ketamine Theophylline

INTRAVENOUS-KETAMINE THEOPHYLLINE Risk of fits Uncertain A careful risk-benefit assessment should be made before using ketamine. However, there are significant benefits for the use of ketamine to anaesthetize patients for emergency management of life-threatening asthma... 

The following agents may be affected by theophylline Benzodiazepines, -agonists, halothane, ketamine, lithium, nondepolarizing muscle relaxants, propofol, ranitidine, and tetracyclines. Probenecid may increase the effects of dyphylline. 

In addition to pharmacokinetic drug-drug interactions, pharmacodynamic effects have been reported as well. Halothane increases the susceptibility to ventricular arrhythmias under theophylline therapy as a result of increased sensitivity of the myocardium to endogenous catecholamine release by theophylUne. Ketamine lowers the theophyUine seizure threshold. Benzodiazepines Uke midazolam, diazepam, lorazepam, and Uurazepam increase the central nervous system concentration of adenosine, a potent central nervous system depressant. As theophyUine also blocks adenosine receptors, it counteracts benzodiazepine-induced sedation, resulting in increased dosage requirements for these compounds. ... 

Over a period of 9 years, tachycardia and extensor-type seizures were observed in 4 patients taking theophylline or aminophylline, who were initially anaesthetised with ketamine, and later with halothane or enllurane." Based on subsequent study in mice, the authors attributed the seizures to an interaction between ketamine and theophylline or aminophylline, and they suggest that the combination should perhaps be avoided in some, or antiseizure premedication be given to patients at risk. However, these cases come from one isolated report. Note that, in mice, ketamine had no effect on aminophylline-induced seizures. ... 

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