Transthyretin amyloid polyneuropathy in France: A cross-sectional study with 413 patients and real-world tafamidis meglumine use (2009-2019).

OBJECTIVE: We aimed to describe characteristics of patients with ATTR variant polyneuropathy (ATTRv-PN) and ATTRv-mixed and assess the real-world use and safety profile of tafamidis meglumine 20mg. METHODS: Thirty-eight French hospitals were invited. Patient files were reviewed to identify clinical manifestations, diagnostic methods, and treatment compliance. RESULTS: Four hundred and thirteen patients (296 ATTRv-PN, 117 ATTRv-mixed) were analyzed. Patients were predominantly male (68.0%) with a mean age of 57.2±17.2 years. Interval between first symptom(s) and diagnosis was 3.4±4.3 years. First symptoms included sensory complaints (85.9%), dysautonomia (38.5%), motor deficits (26.4%), carpal tunnel syndrome (31.5%), shortness of breath (13.3%), and unexplained weight loss (16.0%). Mini-invasive accessory salivary gland or punch skin and nerve biopsies were most common, with a performance of 78.8-100%. TTR genetic sequencing, performed in all patients, revealed 31 TTR variants. Tafamidis meglumine was initiated in 156/214 (72.9%) ATTRv-PN patients at an early disease stage. Median treatment duration was 6.00 years in ATTRv-PN and 3.42 years in ATTRv-mixed patients. Tafamidis was well tolerated, with 20 adverse events likely related to study drug among the 336 patients. CONCLUSION: In France, ATTRv patients are usually identified early thanks to the national network and the help of diagnosis combining genetic testing and mini-invasive biopsies.

[Idiosyncratic drug-induced agranulocytosis: 7 year-analysis in a French university hospital]. / Agranulocytoses médicamenteuses idiosyncrasiques : analyse de 7 ans dans un hôpital universitaire français.

INTRODUCTION: Idiosyncratic drug-induced agranulocytosis is a rare but potentially serious haematological disorder. The pathophysiological mechanisms are complex and poorly understood. We aimed at investigating agranulocytosis drug related causes from the myelograms with "myeloid maturation arrest" performed in our university hospital over the last seven years. METHODS: A retrospective analysis of myelograms collected for agranulocytosis was performed from 1st January 2010 to 31th December 2016. We used the method of Bégaud et al. for drug causality assessment. RESULTS: Among the 104 myelograms analysed, 41 agranulocytosis were drug-induced, whose 28 were idiosyncratic. Among these 28 cases, 26 different drugs were involved. Agranulocytosis was a known adverse reaction in the summary of the product characteristics for 24 drugs, mainly associated with undetermined frequency (n=7). Mean onset latency was 38.1 days after starting the drug (calculated for n=23 cases) and granulocyte growth factors were used in 50% of cases without shortening the mean delay of blood count recovery. Bone marrow presented hypereosinophilia in 29% of cases. Pharmacovigilance reporting rate was 48%. CONCLUSION: A "maturation arrest" in the myelogram is not pathognomonic for idiosyncratic drug-induced agranulocytosis. This rare event require multidisciplinary care involving haematologists, biologists and pharmacovigilance experts. Agranulocytosis reporting rate was high compared with usual adverse drug reaction reporting rate (5 to 10%), probably related to the potential severity of this event.

[Case report: Neuroleptic malignant syndrome and diagnostic difficulties]. / Syndrome malin des neuroleptiques et difficultés diagnostiques : à propos d'un cas.

BACKGROUND: Neuroleptic malignant syndrome (NMS) is an uncommon but potentially fatal adverse effect of neuroleptic drugs. It is commonly characterized by muscular rigidity, fever, altered mental status, and autonomic dysfunction. Emerging of NMS is possible with all neuroleptics, classic and atypical. NMS occurs most often during the first week of treatment or after increasing the dosage of the neuroleptic medication. The frequency of NMS ranges from 0.07 to 2.2%. Its pathophysiology is not clearly understood but the blockade of dopamine receptors appears to be the central mechanism. Issues of NMS are those of diagnosis, treatment and reintroduction of antipsychotic treatment or not. OBJECTIVE: We here present an interesting case because of its atypical clinical presentation and its slow resolution, illustrating the various problems linked to the NMS. CASE REPORT: A 55-year-old woman with a history of mental retardation and infantile psychosis is hospitalized for worsening of her psychiatric symptoms. She is treated by risperidone long-acting injection every 2weeks, escitalopram 20 mg/d and oxazepam 10 mg/d. Early December 2012, she had fever spikes treated with many antibiotics and neuroleptics were stopped, without improvement. Early January 2013, a pulmonary embolism was diagnosed, and a treatment with loxapine is introduced and her injection of risperidone is done because of the state of agitation of the patient. Two weeks later, a NMS is suspected to hyperthermia, tremor of the limbs, a slight stiffness, and neuroleptics are stopped. Dantrolene is then introduced, but after 7days of treatment the fever is still important. Other assumptions are then discussed: infection, serotonin syndrome, encephalopathy, catatonia, malignant hyperthermia. But diagnosis of NMS is finally retained because of the recurrence of symptoms after introduction of clozapine early February. DISCUSSION: In this patient, diagnosis was made more difficult by the use of long-acting neuroleptic. NMS was indeed partly rejected because of the lack of improvement despite 7 days of dantrolene treatment, but the release of risperidone lasts 7weeks after the injection. This NMS is also of atypical presentation with a minor muscular rigidity. And this case is particularly interesting because of the recurrence of NMS with clozapine, allowing to finally diagnose it. This atypical neuroleptic is not known to be a major provider of NMS but the very short period before reintroduction and possible persistence of risperidone in the body could explain the recurrence. CONCLUSION: NMS can be hard to diagnose. It is a diagnosis of exclusion, but we should keep in mind that there is great variability of its clinical presentation in order to not exclude too quickly this syndrome in a patient treated by neuroleptic.

[Experience feedback committee: a method for patient safety improvement]. / Le comité de retour d'expérience (CREX): une méthode pour l'amélioration de la sécurité des soins.

BACKGROUND: An experience feedback committee (CREX, Comité de Retour d'EXpérience) is a method which contributes to the management of safety of care in a medical unit. Originally used for security systems of civil aviation, the method has been adapted to health care facilities and successfully implemented in radiotherapy units and in other specialties. METHODS: We performed a brief review of the literature for studies reporting data on CREX established in hospitals. The review was performed using the main bibliographic databases and Google search results. RESULTS: The CREX is designed to analyse incidents reported by professionals. The method includes monthly meetings of a multi-professional committee that reviews the reported incidents, chooses a priority incident and designates a "pilot" responsible for investigating the incident. The investigation of the incident involves a systemic analysis method and a written synthesis presented at the next meeting of the committee. The committee agrees on actions for improvement that are suggested by the analysis and follows their implementation. Systems for the management of health care, including reporting systems, are organized into three levels: the medical unit, the hospital and the country as a triple loop learning process. The CREX is located in the base level, short loop of risk management and allows direct involvement of care professionals in patient safety. CONCLUSION: Safety of care has become a priority of health systems. In this context, the CREX can be a useful vehicle for the implementation of a safety culture in medical units.

L-2-hydroxyglutaric aciduria diagnosed in a young adult with progressive cerebellar ataxia and facial dyskinesia.

INTRODUCTION: L-2-hydroxyglutaric aciduria is a rare metabolic disorder with quite typical radiological abnormalities and various clinical symptoms. OBSERVATION: A 19-year-old girl presented with ataxia, facial dyskinesia, and mild cognitive impairment. Cerebral magnetic resonance imaging demonstrated subcortical white matter T2 abnormalities and a suggestive rim hyperintensity around the caudate nuclei and the putamen. Diagnosis was confirmed by increased 2-hydroxyglutaric acid in urine and a genetic study (Gly260Ala mutation in the L-2-hydroxyglutarate dehydrogenase (L2HGDH) gene). DISCUSSION: This case highlights the movement disorder onset and radiological aspects that should indicate the L-2-hydroxyglutaric aciduria diagnosis.

SARS-CoV-2 nosocomial infection acquired in a French university hospital during the 1st wave of the Covid-19 pandemic, a prospective study.

BACKGROUND: In healthcare facilities, nosocomial transmissions of respiratory viruses are a major issue. SARS-CoV-2 is not exempt from nosocomial transmission. Our goals were to describe COVID-19 nosocomial cases during the first pandemic wave among patients in a French university hospital and compliance with hygiene measures. METHODS: We conducted a prospective observational study in Grenoble Alpes University Hospital from 01/03/2020 to 11/05/2020. We included all hospitalised patients with a documented SARS-CoV-2 diagnosis. Nosocomial case was defined by a delay of 5 days between hospitalisation and first symptoms. Hygiene measures were evaluated between 11/05/2020 and 22/05/2020. Lockdown measures were effective in France on 17/03/2020 and ended on 11/05/2020. Systematic wearing of mask was mandatory for all healthcare workers (HCW) and visits were prohibited in our institution from 13/03/2021 and for the duration of the lockdown period. RESULTS: Among 259 patients included, 14 (5.4%) were considered as nosocomial COVID-19. Median time before symptom onset was 25 days (interquartile range: 12-42). Eleven patients (79%) had risk factors for severe COVID-19. Five died (36%) including 4 deaths attributable to COVID-19. Two clusters were identified. The first cluster had 5 cases including 3 nosocomial acquisitions and no tested HCWs were positive. The second cluster had 3 cases including 2 nosocomial cases and 4 HCWs were positive. Surgical mask wearing and hand hygiene compliance were adequate for 95% and 61% of HCWs, respectively. CONCLUSIONS: The number of nosocomial COVID-19 cases in our hospital was low. Compliance regarding mask wearing, hand hygiene and lockdown measures drastically reduced transmission of the virus. Monitoring of nosocomial COVID-19 cases during the first wave enabled us to determine to what extent the hygiene measures taken were effective and patients protected. Trial registration Study ethics approval was obtained retrospectively on 30 September 2020 (CECIC Rhône-Alpes-Auvergne, Clermont-Ferrand, IRB 5891).

[Results of 4 years of microbiological testing of bronchoscopes]. / Endoscopes bronchiques: bilan de quatre années de contrôles microbiologiques.

INTRODUCTION: In the context of reducing endoscopy-related infectious risk and new national guidelines on microbiological samples from bronchoscopy, the results of a surveillance program set up in a hospital center were analyzed. METHODS: Over 4 years, scheduled samples were taken from disinfected bronchoscopes. Bacteriology and mycology tests were used to search for microorganisms. The results were interpreted as falling within three levels: target, alert, and action. Factors that could explain the contamination were studied: age of the bronchoscope, number of uses per year, brand, and model. RESULTS: Out of 96 scheduled samples taken, the compliance rate for the period was 83% and increased (p=0.06) over the 4 years. We identified 15 Pseudomonas (six aeruginosa and nine other species), one Stenotrophomonas, one enterobacterium, and two filamentous fungi. None of the factors studied had a significant effect on sample contamination. CONCLUSION: The microbiological surveillance of bronchoscopes is an indispensable part of the quality assurance of bronchoscope maintenance. It can lead to maintenance of the bronchoscope when a noncompliant result is found.

[Polidocanol induced cardiotoxicity: a case report and review of the literature]. / Toxicité cardiaque du polidocanol: rapport d'un cas et revue de la littérature.

OBJECTIVE: Polidocanol foam sclerotherapy is a treatment of symptomatic venous disease. This solution is highly valued by clinicians because of its high efficacy and excellent safety profile. Systemic adverse effects are rare. Some life-threatening reactions have been reported. We report a case of respiratory and cardiac arrest, and a literature review on the cardiac toxicity of polidocanol used within and outside their licensed indications. MAIN OUTCOME MEASURES: A 48-year-old woman, with a symptomatic venous disorder, CEAP grade C2, was treated by echosclerotherapy for a great saphenous vein. She developed a malaise and respiratory and cardiac arrest occurred within minutes after a 7 ml foam polidocanol injection. Cardiopulmonary resuscitation was immediately started before restoration of pulses. A literature search was done using the Medline database. RESULTS: Five cases of cardiac toxicity were reported with polidocanol, but four of them were used outside their licensed indications. Because of the very suggestive chronology and the lack of any other obvious etiology, this cardiac arrest was attributed to polidocanol. Initial ST-segment elevation and negativity of anaphylaxis markers suggest a direct myocardial toxicity. CONCLUSIONS: Clinicians should be aware of the possibility of little-known but potentially serious cardiac adverse reaction with polidacanol injection and be prepared to initiate cardiopulmonary resuscitation if needed.

Incidence and prevention of infective endocarditis and bacteraemia after transcatheter aortic valve implantation in a French university hospital: a retrospective study.

Infective endocarditis (IE) after transcatheter aortic valve implantation (TAVI) is a rare but severe complication. Among 326 patients who underwent TAVI at Grenoble Alpes University Hospital, six (1.8%) cases of IE and 11 (3.4%) cases of bacteraemia were identified. No cases of IE were linked to the intervention; one was due to Staphylococcus aureus despite a screening and targeted decolonization strategy. This underscores the need for randomized studies to evaluate the benefit and cost-effectiveness of this policy.

A neonatal specialist with recurrent methicillin-resistant Staphylococcus aureus (MRSA) carriage implicated in the transmission of MRSA to newborns.

This study reports an investigation of outbreaks of methicillin-resistant Staphylococcus aureus (MRSA) infection and colonization involving 17 newborns in the neonatal unit of a teaching hospital. A neonatal specialist colonized with MRSA that eventually became mupirocin-resistant was implicated as a recurrent source of transmission of MRSA to newborns.

Evaluation of a new packaging process for non-autoclavable endoscopes: results for the first 100 microbiological samples.

BACKGROUND: A new process for packaging endoscopes (SureStore®, Medical Innovations Group) immediately after they exit from washing and disinfection in an automated endoscope reprocessor (AER) allows for endoscopes to be stored for up to 15 days. AIM: To describe the microbiological quality of samples from gastrointestinal endoscopes following this process. METHODS: Three-month prospective study using microbiological sampling from a stock of 38 gastrointestinal endoscopes carried out in a French University Hospital. The compliance rate (proportion of samples ≤25 cfu with no pathogenic micro-organisms) and the rate of sterile samples (proportion of germ-free samples) were calculated. We then used multivariate analysis to determine the factors associated with the maintenance of sterility. FINDINGS: One hundred samples were taken from stored endoscopes: 31 stored for ≤3 days, 34 stored between 3 and 7 days, and 35 after storage between 7 and 15 days. The compliance rate was 98% and the sterile sample rate was 60%. Only the time between leaving the AER and packaging was significantly associated with the sterility of samples (P = 0.02). The probability of having a sterile sample decreased 17-fold when the endoscope was packaged >2 h after leaving the AER (P = 0.04) compared to an endoscope packaged within 1 h after leaving the AER. CONCLUSION: The SureStore process seems capable of satisfactorily maintaining compliance (98%) of samples taken from endoscopes stored for up to 15 days. The delay in packaging should not exceed 1 h, as the rate of sterile samples decreases thereafter.

Deciphering the causes of sporadic late-onset cerebellar ataxias: a prospective study with implications for diagnostic work.

The management of sporadic late-onset cerebellar ataxias represents a very heterogeneous group of patients and remains a challenge for neurologist in clinical practice. We aimed at describing the different causes of sporadic late-onset cerebellar ataxias that were diagnosed following standardized, exhaustive investigations and the population characteristics according to the aetiologies as well as at evaluating the relevance of these investigations. All patients consecutively referred to our centre due to sporadic, progressive cerebellar ataxia occurring after 40 years of age were included in the prospective, observational study. 80 patients were included over a 2 year period. A diagnosis was established for 52 patients (65%) corresponding to 18 distinct causes, the most frequent being cerebellar variant of multiple system atrophy (n = 29). The second most frequent cause was inherited diseases (including spinocerebellar ataxias, late-onset Friedreich's disease, SLC20A2 mutations, FXTAS, MELAS, and other mitochondrial diseases) (n = 9), followed by immune-mediated or other acquired causes. The group of patient without diagnosis showed a slower worsening of ataxia (p < 0.05) than patients with multiple system atrophy. Patients with later age at onset experienced faster progression of ataxia (p = 0.001) and more frequently parkinsonism (p < 0.05) than patients with earlier onset. Brain MRI, DaT scan, genetic analysis and to some extent muscle biopsy, thoracic-abdominal-pelvic tomodensitometry, and cerebrospinal fluid analysis were the most relevant investigations to explore sporadic late-onset cerebellar ataxia. Sporadic late-onset cerebellar ataxias should be exhaustively investigated to identify the underlying causes that are numerous, including inherited causes, but dominated by multiple system atrophy.

Hospital-wide prospective mandatory surveillance of invasive aspergillosis in a French teaching hospital (2000-2002).

A multidisciplinary working group devoted to epidemiological surveillance of invasive aspergillosis (IA) was created in January 2000 in Grenoble University Hospital. This article presents the results of a three-year IA surveillance. The multidisciplinary working group surveyed all hospitalized patients, and the mycology laboratory detected most suspected IA cases. Cases were reviewed monthly by the Aspergillosis Committee, and were classified according to international consensus criteria. Possible nosocomial acquisition was determined. Among the 490 alerts, 74 IA cases were observed: six proven cases (8%), 36 (49%) probable cases and 32 (43%) possible cases. The incidence was 4.4 (95% CI 3.4-5.4) IA/100 000 patient-days. Among the proven and probable IA cases, we observed 10 nosocomial cases and six cases of undetermined origin. No cases were noted in the protected rooms in the haematology unit. Only one cluster of cases (three nosocomial cases) was detected in the haematology unit. Forty-three percent of cases (N=32) were hospitalized in the haematology unit, and all other cases were hospitalized elsewhere. This three-year survey found a high rate of non-nosocomial IA cases and a high frequency of IA cases hospitalized in units other than haematology. Thus, this study shows the importance of IA surveillance in haematology units and all high-risk units.

En-suite bathrooms in protected haematology wards: a source of filamentous fungal contamination?

BACKGROUND: In spite of 25 recently built high-risk haematology rooms with a protected environment and fitted with en-suite bathrooms in our university hospital centre in 2008, sporadic cases of hospital-acquired invasive aspergillosis remained in these wards. AIM: This study aimed to identify unsuspected environmental sources of filamentous fungal contamination in these rooms. METHODS: Over two months, environmental fungal flora in the air (150 samples) as well as air particle counting and physical environmental parameters (airspeed, temperature, humidity, pressure) were prospectively monitored twice on the sampling day in all 25 protected rooms and en-suite bathrooms in use, and on bathroom surfaces (150 samples). FINDINGS: In rooms under laminar airflow, in the presence of patients during sampling sessions, fungi were isolated in two samples (4%, 2/50) with a maximum value of 2cfu/500L (none was Aspergillus sp.). However, 88% of the air samples (44/50) in the bathroom were contaminated with a median range and maximum value of 2 and 16cfu/500L. Aspergillus spp. were involved in 24% of contaminated samples (12/44) and A. fumigatus in 6% (3/44). Bathroom surfaces were contaminated by filamentous fungi in 5% of samples (8/150). CONCLUSION: This study highlighted that en-suite bathrooms in protected wards are likely to be a source of fungi. Before considering specific treatment of air in bathrooms, technicians have first corrected the identified deficiencies: replacement of high-efficiency particulate air filters, improvement of air control automation, and restoration of initial technical specifications. Assessment of measure effectiveness is planned.

Monitoring rotavirus environmental contamination in a pediatric unit using polymerase chain reaction.

Rotavirus environmental contamination in a pediatric unit was investigated. Surfaces were swabbed, then viruses eluted, ultracentrifuged, and detected by polymerase chain reaction (PCR) amplification. Of 55 samples, 25 (46%) tested positive. Rotavirus RNA was more prevalent on surfaces in direct contact with children (thermometers and play mats) than on other environmental surfaces (washbasins, door handles, etc). PCR has proved useful for monitoring rotavirus environmental contamination.

Evaluation of dextromethorphan and dextrorphan as a preventive treatment of soman toxicity in mice.

Phencyclidine-like drugs are effective against convulsions and brain lesions related to soman intoxication but induce severe side effects. The well tolerated antitussive dextromethorphan (DM) and its metabolite dextrorphan (DX) have antiepileptic and neuroprotective properties that we evaluated in mice against 2 LD50 of soman in a three-drug pretreatment (atropine sulfate and oxime HI-6 plus DM: 20-50 mg/kg or DX: 10-40 mg/kg i.p). Neuroprotection was evaluated by measurement of hippocampal omega 3 binding site density. DM and DX have weak anticonvulsant and neuroprotective activities which are counterbalanced at high doses by an increased mortality due to respiratory distress for DM and by ataxia for DX. Thus DM and DX do not appear to be appropriate for the pretreatment of soman intoxication.

Eight-year surveillance of environmental fungal contamination in hospital operating rooms and haematological units.

An eight-year fungal environmental surveillance was carried out in 15 operating theatres and two haematological units. Sampling was performed twice a year in each room, using contact plates for plane surfaces and sterile swabs for grids. From 1992 to 1999, individual rooms in the 17 units were sampled on 1094 occasions and 3822 samples were collected. The percentage of rooms without fungus increased regularly between 1992 and 1999 (41.1% and 74.8%, respectively). The units were classified according to the fungal contamination during the eight years: the operating theatres which required the highest protection (cardiological, thoracic, vascular, hand, orthopaedic and neurosurgery) and the adult haematological unit showed least contamination (71.8% rooms were negative). The most frequent species isolated were Penicillium spp. (28.4%), Cladosporium spp. (15.6%) and Aspergillus spp. (7.6%). Aspergillus fumigatus was rarely isolated (3.7%), and was mainly isolated at the beginning of the study. This study demonstrates that environmental control programmes are effective in reducing environmental mould contamination and could be useful in establishing exposure guidelines, especially by defining an acceptable level of biocontamination in zones at risk.

Dextromethorphan and dextrorphan in rats: common antitussives--different behavioural profiles.

Dextromethorphan (DM), a widely used and well-tolerated centrally acting antitussive, has been tested in several clinical trials for its antiepileptic and neuroprotective properties. However, the use of DM in these new clinical indications requires higher doses than antitussive doses, which may therefore induce phencyclidine (PCP)-like side-effects (memory and psychotomimetic disturbances) through its metabolic conversion to the active metabolite dextrorphan (DX), a more potent PCP-like non-competitive antagonist at the N-methyl-D-aspartate (NMDA) receptor than DM. Thus, we compared the behavioural effects in rats of intraperitoneal administration of DM and DX on motor activity in an open field and on learning and memory in the Morris water maze. DM (20, 30, 40 mg/kg) produced a dose-dependent decrease in both locomotion and stereotyped behaviour with a slight ataxia for the highest dose. DX (20, 30, 40 mg/kg) induced a dose-dependent increase in locomotion and stereotypies (swaying, turning) with moderate ataxia. Assessments of learning and memory were performed with lower doses of DM (10, 20, 30 mg/kg) and DX (5, 10, 15 mg/kg) because of motivational deficits (40 mg/kg of DM, 20-40 mg/kg of DX) and motor disorders (30, 40 mg/kg of DX) in the cue learning procedure. DX (10, 15 mg/kg) impaired spatial learning with a long-lasting effect for the highest dose whereas 5 mg/kg of DX and DM (10-30 mg/kg) did not. Only 15 mg/kg of DX appeared to slightly impair working memory. DM (10-30 mg/kg) and DX (5-15 mg/kg) did not impair reference memory. Thus, the two antitussives DM and DX induced different behavioural effects suggesting sedative effects for DM and PCP-like effects for DX. However, PCP-like side-effects with DM remain possible through its metabolic conversion to DX, with very high doses and/or in extensive metabolizers and/or in aged subjects prone to cognitive dysfunction. Therefore, the identification of DM metabolism phenotype, an adapted prescription and a pharmacological modulation of the DM metabolism may avoid adverse effects.

Antagonism of metergoline on the diuretic effect of cyclazocine and U-50488 drugs with a kappa agonist activity.

In rats receiving a normal saline load of 2.5 ml/100 g, sc, (moderately hydrated rats), injections of the serotonin (5-HT) antagonist, metergoline (0.25-1-4 mg/kg), resulted in a dose-dependent decrease in the urine output induced by a dose of 8 mg/kg of cyclazocine (a benzomorphan derivative, mixed kappa and sigma agonist) at the 2-h time period. The antagonist effect of metergoline (1 mg/kg) on cyclazocine doses ranging from 0.25 to 8 mg/kg, was observed only at 2 mg/kg higher doses. Other 5-HT receptor blockers, methysergide, pizotifen, cyproheptadine, caused a significant degree of antagonism. In rats receiving a saline load and a water load of 5.5 ml/100 g, ip (hyperhydrated rats), metergoline (1 mg/kg) completely antagonized the diuretic effect of cyclazocine (8 mg/kg) at the 4-h and 5-h time periods. Similarly, metergoline (1 and 4 mg/kg) administered in moderately hydrated rats, markedly decreased at the 2-h time period, the urine output produced by 5 mg/kg of U-50488 (a non benzomorphan derivative, highly selective kappa agonist), and in hyperhydrated rats, completely suppressed, at the 4-h and 5-h time periods the drug-induced diuresis. Metergoline administered alone had no effect on urine output in moderately hydrated rats or in hyperhydrated rats. These results suggest the hypothesis that 5-HT may be involved in the complex mechanisms of kappa agonist-induced diuresis in rats.