BACLOFEN TOXICITY IN PATIENTS WITH SEVERELY IMPAIRED RENAL-FUNCTION

OBJECTIVE: To report the toxic effects of baclofen in patients with se verely impaired renal function. DATA SOURCES: From 1991 to 1995, nine patients with severely impaired renal function (2 not receiving dialys is, 1 undergoing continuous ambulatory peritoneal dialysis [CAPD], and 6 receiving maintenance hemodialysis), who exhibited clinical toxicit y after baclofen therapy at our hospital were included for analysis. A nother seven cases from the literature obtained by computerized (MEDLI NE) and manual (Index Medicus) search methods published between 1980 a nd 1995 were also reviewed. INTERVENTION: Among our nine patients, the six undergoing chronic hemodialysis and one not undergoing dialysis r eceived early (<48 h) hemodialysis after toxic symptoms developed. The patient undergoing CAPD received late hemodialysis (>72 h), and the o ther patient who had not undergone dialysis received only supportive c are. RESULTS: A review of these 16 cases revealed that most patients r eceived only small doses and very short-term baclofen therapy. Altered consciousness was the major presenting feature. Severe acute complica tions, such as seizures and respiratory depression, were relatively un common among patients with severely impaired renal function. However, abdominal pain, which has previously rarely been reported, was noted i n five of our nine patients. Most patients showed clinical improvement after hemodialysis. An analysis of these nine patients revealed that those who received early hemodialysis had a shorter recovery time than the patient who received only supportive care (2.71 +/- 0.42, respect ively, vs. 9 d; p < 0.01). A lag of several hours between the end of t he hemodialysis session and an improvement in the level of consciousne ss was noted. DISCUSSION: As most patients with severely impaired rena l function developed toxic symptoms soon after initiating a low-dose b aclofen regimen, the accumulated dosage was small and severe complicat ions were less common. Abdominal pain may have occurred as a result of the gamma-aminobutyric acid-mediated cholinergic effect exerted by ba clofen. The delay in conscious recovery after hemodialysis may be due to a delay in the clearance of baclofen from the central nervous syste m. CONCLUSIONS: Patients with severely impaired renal function general ly develop baclofen intoxication soon after the initiation of low-dose therapy. Thus, the administration of baclofen, regardless of the dosa ge, in these patients is not appropriate. Abdominal pain, in addition to altered consciousness, is a common presenting feature in patients w ith renal failure who have baclofen intoxication. Hemodialysis is effe ctive in alleviating the clinical symptoms and shortening the recovery time for such patients.