Severe respiratory depression by low-dose baclofen in the treatment of chronic hiccups in a patient undergoing CAPD

Recommendations from the EXTRIP workgroup on extracorporeal treatment for baclofen poisoning

Baclofen toxicity results from intentional self-poisoning ("acute baclofen poisoning") or accumulation of therapeutic dose in the setting of impaired kidney function. Standard care includes baclofen discontinuation, respiratory support and seizure treatment. Use of extracorporeal treatments (ECTRs) is controversial. To clarify this, a comprehensive review of the literature on the effect of ECTRs in baclofen toxicity was performed and recommendations following EXTRIP methods were formulated based on 43 studies. (1 comparative cohort, 1 aggregate results cohort, 1 pharmacokinetic modeling, and 40 patient reports or series). Toxicokinetic data were available for 20 patients. Baclofen's dialyzability is limited by a high endogenous clearance and a short half-life in patients with normal kidney function. The workgroup assessed baclofen as "Moderately dialyzable" by intermittent hemodialysis for patients with normal kidney function (quality of evidence C) and "Dialyzable" for patients with impaired kidney function (quality of evidence C). Clinical data were available for 25 patients with acute baclofen poisoning and 46 patients with toxicity from therapeutic baclofen in kidney impairment. No deaths or sequelae were reported. Mortality in historical controls was rare. No benefit of ECTR was identified in patients with acute baclofen poisoning. Indirect evidence suggests a benefit of ECTR in reducing the duration of toxic encephalopathy from therapeutic baclofen in kidney impairment. These potential benefits were balanced against added costs and harms related to the insertion of a catheter, the procedure itself, and the potential of baclofen withdrawal. Thus, the EXTRIP workgroup suggests against performing ECTR in addition to standard care for acute baclofen poisoning and suggests performing ECTR in toxicity from therapeutic baclofen in kidney impairment, especially in the presence of coma requiring mechanical ventilation.

Pharmacologic Interventions for Intractable and Persistent Hiccups: A Systematic Review

BACKGROUND

Chlorpromazine is the only drug approved by the US Food and Drug Administration for the treatment of hiccups; however, many other pharmacologic treatments have been proposed for intractable and persistent hiccups. Currently, there is little evidence to support the use of one agent over another.

OBJECTIVE

This review aims to identify literature concerning the use of pharmacologic treatments for intractable and persistent hiccups with the goal of evaluating therapies in terms of their level of evidence, mechanism of action, efficacy, dosing, onset of action, and adverse effects.

METHODS

A systematic literature search of PubMed, Embase, the Cochrane Library, and the New York Academy of Medicine was performed to find articles where a pharmacologic agent was used to treat intractable or persistent hiccups between the years 1966 and 2016. The GRADE method was used to assess the level of evidence for the studies included in this review.

RESULTS

This review identified 26 articles involving 10 pharmacologic treatment options that met our inclusion criteria. Amitriptyline, baclofen, gabapentin, haloperidol, metoclopramide, midazolam, nifedipine, nimodipine, orphenadrine, and valproic acid were found in the literature to be successful in treating hiccups.

CONCLUSION

Baclofen, gabapentin, and metoclopramide were the only agents that were studied in a prospective manner, while only baclofen and metoclopramide were studied in randomized controlled trials. No specific recommendations can be made for treating intractable and persistent hiccups with the evidence currently available in the literature. Therapy selection should be specific to individual patients, their underlying comorbidities, etiology of hiccups, and take into account the individual properties of the drugs.

Baclofen Toxicity in Kidney Disease

Baclofen, a commonly prescribed muscle relaxant, is primarily excreted via the kidneys; toxicity is a potentially serious adverse outcome in patients with decreased kidney function. We describe a patient with end-stage kidney disease receiving hemodialysis who developed neurotoxicity and hemodynamic instability after receiving baclofen for muscle spasms. In this case, prompt recognition of baclofen toxicity and urgent hemodialysis were effective in reversing this toxicity. This case is used to examine the pharmacokinetics and pathophysiology of baclofen toxicity and discuss appropriate diagnosis and management of baclofen toxicity. We recommend reducing the baclofen dose in patients who have moderately reduced kidney function (estimated glomerular filtration rate, 30-60mL/min/1.73m²) and avoiding use in patients with severely reduced kidney function (estimated glomerular filtration rate < 30mL/min/1.73m²) or on renal replacement therapy.

Baclofen-induced encephalopathy in patient with end stage renal disease: Two case reports

We report two end stage renal disease (ESRD) patients, who rapidly developed neurotoxicity after taking baclofen, a centrally acting gamma-aminobutyric acid agonist. They presented to our hospital in a state of confusion. On physical examination, there were no focal neurological deficits and the remainder of the examination was also not diagnostic. Laboratory data were unremarkable. The consciousness improved with supportive treatment and intensive hemodialysis over 3-4 days. In conclusion, physicians should be aware of the possibility of baclofen-induced neurotoxicity in patients with renal disease, especially in ESRD patients and it is necessary to avoid or reduce baclofen dosage in these patients.

Antitussive effects of the peripherally restricted GABAB receptor agonist lesogaberan in guinea pigs: comparison to baclofen and other GABAB receptor-selective agonists

BACKGROUND

Gastroesophageal reflux disease (GERD) is a common cause of chronic cough. Both acid and nonacid reflux is thought to play a role in the initiation of coughing and cough hypersensitivity. The GABAB receptor agonist lesogaberan was developed as a peripherally restricted anti-reflux therapy that reduces the frequency of transient lower esophageal sphincter relaxations (TLESR; the major cause of reflux) in animals and in patients with GERD. GABAB receptor agonists have also been shown to possess antitussive effects in patients and in animals independent of their effects on TLESR, suggesting that lesogaberan may be a promising treatment for chronic cough.

METHODS

We have assessed the direct antitussive effects of lesogaberan (AZD3355). The effects of other GABAB receptor agonists were also determined. Coughing was evoked in awake guinea pigs using aerosol challenges with citric acid.

RESULTS

Lesogaberan dose-dependently inhibited citric acid evoked coughing in guinea pigs. Comparable effects of the GABAB receptor agonists baclofen and 3-aminopropylphosphinic acid (3-APPiA) on cough were also observed. Baclofen produced obvious signs of sedation and respiratory depression. By contrast, both lesogaberan and 3-APPiA (both inactivated centrally by GABA transporters) were devoid of sedative effects and did not alter respiratory rate.

CONCLUSIONS

Together, the data suggest that lesogaberan and related GABAB receptor agonists may hold promise as safe and effective antitussive agents largely devoid of CNS side effects.

Baclofen toxicity in patients with advanced nephropathy: proposal for new labeling

BACKGROUND

Despite several reports in the literature of baclofen toxicity in patients with renal dysfunction, the drug is being used for many patients.

METHODS

Herein we report a case of baclofen-induced encephalopathy in a patient with pre-end-stage renal disease and review the literature regarding the magnitude of baclofen toxicity in patients with renal insufficiency. A Medline search for studies in English was performed. Twenty-one case reports involving 41 patients (including our patient) were identified.

RESULTS

The majority of patients were elderly (62.5% above 60 years) males (56.3%) on dialysis (62.9%). Neurotoxicities were almost always present at presentation. Manifestations of baclofen toxicity usually started 2-3 days after starting baclofen; however, periods as long as 16 weeks have been reported. The daily dose of baclofen ranged from 5 to 60 mg with a mean dose of 20 mg. Hemodialysis (HD) was the most common treatment modality used for drug elimination (65.7%). The recovery time ranged from 2 h in patients who received HD, to 8 days with conservative treatment.

CONCLUSION

The literature does not mention a clear recommendation about baclofen safety and dose adjustment, or a minimum level of kidney function below which the drug should not be used.

Baclofen: Hiccups

This Hospital Pharmacy feature is extracted from Off-Label Drug Facts, a quarterly publication available from Wolters Kluwer Health. Off-Label Drug Facts is a practitioner-oriented resource for information about specific drug uses that are unapproved by the US Food and Drug Administration. This new guide to the literature enables the health care professional or clinician to quickly identify published studies on off-label uses and determine if a specific use is rational in a patient care scenario. A summary of the most relevant data is provided, including background, study design, patient population, dosage information, therapy duration, results, safety, and therapeutic considerations. References direct the reader to the full literature for more comprehensive information before patient care decisions are made. Direct questions or comments regarding Off-Label Drug Uses to jgeneral@kumc.edu .

Prolonged unconsciousness in a patient on automated peritoneal dialysis

A 79-year-old man with end-stage renal disease treated by automated peritoneal dialysis was referred to the emergency department for altered consciousness. The first investigations, including toxicology screening, failed to reveal the precise etiology. The patient was treated for a possible seizure. After the progression of central nervous system depression with bradypnea, the patient was intubated and mechanically ventilated. It appeared later on that he had ingested by mistake one of his wife's medications, baclofen. Baclofen was detected in the blood sampled on admission at a level above the therapeutic range. Baclofen is mainly excreted by the kidney. A short-term administration of low-dose of baclofen is not effectively removed by peritoneal dialysis and may result in prolonged but reversible coma.

Management of hiccups in the palliative care population

There are close to a hundred causes for hiccups, or singultus, the most common of which are gastrointestinal. Causes may be natural or drug induced, and the same agents that are used to treat hiccups may also induce them. Hiccups can be classified by their duration, as follows: up to 48 hours, acute; longer than 48 hours, persistent; and more than two months, intractable. Treatment options for hiccups can include both pharmacologic and nonpharmacologic agents. If the cause of hiccups can be identified, it is, of course, preferable to direct the treatment at that cause. However many times a cause cannot be identified; in this case, general measures or treatments should be instituted. Intractable hiccups can occur in the palliative care population. When they do, it can be extremely distressing and have a significant impact on quality of life. Pharmacologic approaches are often the most rational therapies for these patients. Baclofen seems to be a promising drug for use with both palliative care and perioperative patients, and using garabentin as an add-on to baclofen may also be a reasonable option to consider

Baclofen neurotoxicity in uremic patients: is continuous ambulatory peritoneal dialysis less effective than intermittent hemodialysis?

OBJECTIVES

To compare the efficacy between continuous ambulatory peritoneal dialysis (CAPD) and intermittent hemodialysis in the treatment of baclofen-associated neurotoxicity.

METHODS

Three uremic patients suffering baclofen-associated neurotoxicity were treated by CAPD at our hospital. We obtain 12 cases with detailed clinical course of baclofen-associated neurotoxicity treated by hemodialysis from a literature review using the Medline and Science Citation Index, six of these patients were treated by early hemodialysis which was defined as hemodialysis intervention within 48 h of the onset of clinical toxicity.

RESULTS

Our cases regain full consciousness within 2-3 days after the onset of neurotoxicity. Clinical characteristics of our cases including age, dialysis time, preexisting central nervous system (CNS) lesion, concomitant use of CNS depressant, total baclofen dose, onset of neurotoxicity, and duration of neurotoxicity are not significantly different from reported cases that treated by either early or routine hemodialysis.

CONCLUSIONS

Baclofen should be avoided in uremic patients. When consciousness disturbance occurs in uremic patients, baclofen-associated neurotoxicity should be included in the list of differential diagnosis. According to experiences of our patients, we conclude that neither early nor routine hemodialysis is more effective than CAPD in shortening the recovery time of baclofen-associated neurotoxicity.