Renal impairment: a challenge for opioid treatment? The role of buprenorphine.

Impairment of renal function is common among elderly patients due to an age-related decline in renal excretory function. In addition, many diseases such as hypertension and diabetes mellitus are associated with an accelerated decline in renal function. Renal dysfunction affects the metabolism of compounds and thus has important therapeutic consequences for drug safety. For pain patients who have reduced renal function such as those in palliative care, most opioids used for chronic pain treatment should be administered at reduced dosages, with increased dosage intervals, or not at all because of the risk of accumulation of the parent compound or its metabolites. For instance, for morphine or codeine, active metabolites are formed in the liver and cleared by the kidney and may therefore accumulate in cases of renal dysfunction. In contrast, buprenorphine can be administered at normal doses in patients with renal dysfunction because it is mainly excreted through the liver. In patients undergoing regular haemodialysis treatment, removal of an opioid during dialysis varies between individuals based upon a number of factors including the dialysis technique used. Morphine appears to be difficult to process in haemodialysis patients due to possible 'rebound' of metabolites between dialysis sessions. By contrast, the pharmacokinetics of buprenorphine are unchanged in haemodialysis patients, which means that there is no need for dose-reduction with this drug. Thus, in patients with reduced renal function, chronic renal insufficiency and haemodialysis, buprenorphine appears to be a safe choice when opioid treatment is initiated.