Acute overdose with sustained release formulations presents special problems for the health care system. Proper management requires a basic understanding of the pharmacokinetic and pharmacodynamic characteristics of the drugs taken in overdose becauseModern pharmaceutical technology permits the use of sustained or slow release formulations. Consequently, the market has been flooded with such preparations for drugs such as theophylline, lithium, potassium, procainamide, disopyramide, phenylpropanolamine, diet aid pills, etc. In the US, there are more than 30 sustained release formulations for theophylline alone available on the market. An increase in the numbers of patients overdosed on such preparations follows inexorably, since 'people take what is handy'.