Interrupting drug therapy in the perioperative period.

Millions of patients undergo surgery each year and an increasing proportion of these patients are consuming therapeutic drugs. Drug therapy is often withheld in the immediate perioperative period and after major surgery, in particular, there is often a prolonged period of fasting. This may lead to withdrawal effects including recurrence or worsening of patients' disease symptomatology. These effects will occur during a period of physiological and pathophysiological stresses and render patients more vulnerable to drug withdrawal phenomena. Thus, patients may be exposed to greater and sometimes unnecessary risks in the perioperative period. There are relatively few studies that have investigated this problem. The ones that have, however, confirm that drug abstinence in the perioperative period is a relatively common phenomenon and one study has demonstrated an association between duration of drug abstinence and adverse outcomes. The pathophysiological effects of major surgery on gastrointestinal function, neuro-humoral and cytokine adaptive responses to surgical stress are under-appreciated. These responses can reduce the effectiveness of oral administration and exacerbate co-existing disease processes. These problems are compounded by a fragmented approach to perioperative drug therapy with no one group of healthcare professionals assuming responsibility for this aspect of care. This may in part be a consequence of the complexities of rationalising drug therapy in the perioperative period together with the lack of readily available and evidence based information strategies for individual drugs or drug classes. An additional problem relates to the formulations, inherent pharmacokinetics and limited routes of administration of many prescribed drugs. These can prevent a 'seamless' transition from preoperative to postoperative management. Consumers, health professionals, pharmaceutical companies and drug regulatory agencies must all play a part in rectifying this problem. There remains a need for further research to clarify the effects of abstinence on patient outcomes and also to identify optimum strategies to avoid unwanted drug abstinence.