Relationship of continuous infusion lorazepam to serum propylene glycol concentration in critically ill adults*

Considerations for deriving a safe intake of propylene glycol

The use of propylene glycol (PG) in food and other applications is widespread, and some estimates of dietary exposure to PG approach or exceed the Acceptable Daily Intake (ADI) of 25 mg/kg bw-day. The current ADI for PG applies a cumulative uncertainty factor of 100, which includes factors of 10 for both interspecies and intraspecies differences. Available toxicology studies and human data, however, indicate a plausible mode of action (MoA) that would support a chemical-specific adjustment factor (CSAF) of 1 for interspecies toxicodynamic differences, reducing the total uncertainty factor from 100 to 40. The MoA involves an increase in serum PG concentrations after metabolic saturation, leading to serum hyperosmolarity, which can ultimately cause hemolytic changes and red blood cell damage. Therefore, the species similarities in toxicodynamic response for this critical effect could support increasing the ADI from 25 to 62.5 mg/kg bw-day, applicable to both children and adults.

Unexplained Metabolic Acidosis: Alcoholic Ketoacidosis or Propylene Glycol Toxicity

INTRODUCTION

Severe metabolic acidosis with elevated anion and osmol gap is suggestive of toxic alcohol ingestion. The absence of detectable methanol or ethylene glycol in the serum could mean that metabolism is complete or that other hypotheses have to be considered. Ingestion of less common alcohol or alcoholic ketoacidosis should be investigated as illustrated by the present observation.

CASE REPORT

A 46-year-old woman was admitted with altered consciousness in the Emergency Department. In the presence of a high anion gap (peak value 39 mEq/L) metabolic acidosis with mildly increased osmol gap (peak value 19 mOsm/kg), there was a high suspicion of toxic alcohol ingestion in an individual with alcohol use disorder (AUD). Serum arterial lactate concentration was particularly high at 27 mmol/L. Urinalysis failed to reveal the presence of ketone bodies or oxalate crystals. The results of the serum determination of ethanol, methanol, ethylene glycol, and isopropanol were obtained within 2 h and were negative. Due to the severity of lactic metabolic acidosis and the persisting suspicion of intoxication by a less common toxic alcohol, antidotal therapy with ethanol was initiated together with hemodialysis. Correction of lactic metabolic acidosis was obtained. Results of urinalysis obtained later revealed the presence not only of propylene glycol and D-lactate but also of significant concentrations of ß-hydroxybutyrate as a marker of alcoholic ketoacidosis.

DISCUSSION

The combination of propylene glycol ingestion and alcoholic ketoacidosis may have contributed to the severity of lactic acidosis.

Time Is Brain: Acute Control of Repetitive Seizures and Status Epilepticus Using Alternative Routes of Administration of Benzodiazepines

Time plays a major role in seizure evaluation and treatment. Acute repetitive seizures and status epilepticus are medical emergencies that require immediate assessment and treatment for optimal therapeutic response. Benzodiazepines are considered the first-line agent for rapid seizure control. Thus, various routes of administration of benzodiazepines have been studied to facilitate a quick, effective, and easy therapy administration. Choosing the right agent may vary based on the drug and route properties, patient’s environment, caregiver’s skills, and drug accessibility. The pharmacokinetic and pharmacodynamic aspects of benzodiazepines are essential in the decision-making process. Ultimately, agents and routes that give the highest bioavailability, fastest absorption, and a modest duration are preferred. In the outpatient setting, intranasal and buccal routes appear to be equally effective and more rapidly administered than rectal diazepam. On the other hand, in the inpatient setting, if available, the IV route is ideal for benzodiazepine administration to avoid any potential absorption delay. In this article, we will provide an overview and comparison of the various routes of benzodiazepine administration for acute control of repetitive seizures and status epilepticus.

Pearls and Pitfalls of Introducing Ketogenic Diet in Adult Status Epilepticus: A Practical Guide for the Intensivist

Background: Status epilepticus (SE) carries an exceedingly high mortality and morbidity, often warranting an aggressive therapeutic approach. Recently, the implementation of a ketogenic diet (KD) in adults with refractory and super-refractory SE has been shown to be feasible and effective. Methods: We describe our experience, including the challenges of achieving and maintaining ketosis, in an adult with new onset refractory status epilepticus (NORSE). Case Vignette: A previously healthy 29-year-old woman was admitted with cryptogenic NORSE following a febrile illness; course was complicated by prolonged super-refractory SE. A comprehensive work-up was notable only for mild cerebral spinal fluid (CSF) pleocytosis, elevated nonspecific serum inflammatory markers, and edematous hippocampi with associated diffusion restriction on magnetic resonance imaging (MRI). Repeat CSF testing was normal and serial MRIs demonstrated resolution of edema and diffusion restriction with progressive hippocampal and diffuse atrophy. She required prolonged therapeutic coma with high anesthetic infusion rates, 16 antiseizure drug (ASD) trials, empiric immunosuppression and partial bilateral oophorectomy. Enteral ketogenic formula was started on hospital day 28. However, sustained beta-hydroxybutyrate levels >2 mmol/L were only achieved 37 days later following a comprehensive adjustment of the care plan. KD was challenging to maintain in the intensive care unit (ICU) and was discontinued due to poor nutritional state and pressure ulcers. KD was restarted again in a non-ICU unit facilitating ASD tapering without re-emergence of SE. Discussion: There are inconspicuous carbohydrates in commonly administered medications for SE including antibiotics, electrolyte repletion formulations, different preparations of the same drug (i.e., parenteral, tablet, or suspension) and even solutions used for oral care-all challenging the use of KD in the hospitalized patient. Tailoring comprehensive care and awareness of possible complications of KD are important for the successful implementation and maintenance of ketosis.

Correlation of osmolal gap with measured concentrations of acetone, ethylene glycol, isopropanol, methanol, and propylene glycol in patients at an academic medical center

The ingestion of toxic alcohols including methanol, ethylene glycol, and isopropanol remains a significant public health problem. These compounds can cause central nervous system depression and, for methanol and ethylene glycol, organ damage from toxic metabolites. The presence of these compounds in serum/plasma can often be determined and monitored by measuring the osmolal gap (OG). However, other compounds originating from endogenous or exogenous sources, such as propylene glycol and acetone, can also increase the OG. Conversion factors can be used to estimate specific concentrations of acetone and toxic alcohols from OG. In this retrospective study, data were analyzed for 260 samples originating from 158 unique patients that had determination of both OG and concentrations for toxic alcohols at an academic medical center central laboratory. Specific analysis included gas chromatography (acetone, isopropanol, methanol, ethylene glycol, propylene glycol) and/or enzymatic assay (ethylene glycol). Many samples also contained ethanol. The data was grouped by type of ingestion. The present study analyzed the relationship between the OG calculated from measured plasma/serum osmolality and the OG estimated by applying conversion factors to measured concentrations of the different compounds. The correlations tend to be linear and vary by compound, with methanol and ethylene glycol having the highest R2 values of 0.93 and 0.95, respectively, consistent with other published studies. Higher variability was seen for the data for isopropanol and acetone. For each of the data subsets, the estimated toxic alcohol concentration calculated using conversion factors from OG tends to overestimate the actual concentration of the compound. Overall, the present study demonstrates the generally linear relationship between OG determined by osmolality and the OG estimated using measured concentrations of acetone and toxic alcohols.

Serious Cardiovascular Adverse Events Reported with Intravenous Sedatives: A Retrospective Analysis of the MedWatch Adverse Event Reporting System

BACKGROUND

Serious cardiovascular adverse events (SCAEs) associated with intravenous sedatives remain poorly characterized.

OBJECTIVE

The objective of this study was to compare SCAE incidence, types, and mortality between intravenous benzodiazepines (i.e., diazepam, lorazepam, and midazolam), dexmedetomidine, and propofol in the USA over 8 years regardless of the clinical setting where it was administered.

METHODS

The Food and Drug Administration's MedWatch Adverse Event Reporting System was searched between 2004 and 2011 using the Evidex^® platform from Advera Health Analytics, Inc. to identify all reports that included one or more of ten different SCAEs (package insert incidence ≥ 1%) and where an intravenous benzodiazepine, dexmedetomidine, or propofol was the primary suspected drug.

RESULTS

Among the 2326 Food and Drug Administration's MedWatch Adverse Event Reporting System cases reported, 394 (16.9%) were related to a SCAE. The presence of a SCAE (vs. a non-SCAE) is associated with higher mortality (34 vs. 8%, p < 0.001). The percentage of cases with one or more SCAE, the case mortality rate (%), and the incidence of each SCAE (per 10⁶ days of sedative exposure), respectively, were benzodiazepines (14, 26, 13) [diazepam (13, 23, 31); lorazepam (15, 43, 14); midazolam (14, 20, 11)]; dexmedetomidine (40, 15, 13); and propofol (17, 39, 7). Propofol (vs. either a benzodiazepine or dexmedetomidine) was associated with more total SCAEs (268 vs. 126, p < 0.001) but a lower incidence (per 10⁶ days of sedative exposure) of SCAE (7 vs. 13, p = 0.0001) and cardiac arrest [6.3 (benzodiazepine) vs. 6.7 (dexmedetomidine) vs. 1.4 (propofol), p < 0.0001].

CONCLUSIONS

Serious cardiac adverse events account for nearly one-fifth of intravenous sedative Food and Drug Administration's MedWatch Adverse Event Reporting System reports. These SCAEs appear to be associated with greater mortality than non-cardiac serious adverse events. Serious cardiac events may be more prevalent with either benzodiazepines or dexmedetomidine than propofol.

Near fatal intoxication by nicotine and propylene glycol injection: a case report of an e-liquid poisoning

BACKGROUND

Concern about intoxication by e-liquid is growing as calls to poison control centers have increased since their introduction. Only three cases of intoxication by injection have been reported worldwide. Our case is unique because of the precise follow-up of a patient who survived a lethal dose of self-injected e-liquid, without other co-intoxication.

CASE PRESENTATION

A 51-year-old male presented to the Emergency Department after injecting himself intravenously (IV) in the forearm with 10 mL of e-liquid (1000 mg of nicotine diluted in propylene glycol). An agitation phase was followed by coma and bradypnoea requiring mechanical ventilation. The patient developed a transitory neurological impairment with the appearance of tetraparesis, gaze palsy and myoclonus due to nicotinic syndrome. The arterial blood gas (ABG) analysis confirmed uncompensated lactic acidosis with an elevated anion gap, which is an expected effect of propylene glycol. The toxicology screen indicated the presence of nicotine and cotinine in the blood and excluded the presence of concomitant intoxication. The patient recovered without sequelae.

CONCLUSION

Even a small quantity of intravenous (IV) e-liquid can lead to an acute intoxication and fatal outcomes due to the toxic effects of nicotine. This case might help emergency doctors cope with acute intoxication by injection of e-liquid and increase their comprehension of the two main substances, nicotine and propylene glycol with overview of their pharmacodynamics and kinetic effects.

Potential consequences of high-dose infusion of ketamine for refractory status epilepticus: case reports and systematic literature review

Our goal was to provide comprehensive data on the effectiveness of ketamine in refractory status epilepticus (RSE) and to describe the potential consequences of long-term ketamine infusion. Ketamine, an N-methyl D-aspartate (NMDA) receptor antagonist, blocks excitatory pathways contributing to ongoing seizure. While ketamine use is standard in anaesthetic induction, no definitive protocol exists for its use in RSE, and little is known about its adverse effects in long-term, high-dose administration. We present two cases of RSE that responded rapidly to ketamine infusion, both with fatal outcomes secondary to metabolic acidosis and cardiovascular collapse. We performed a systematic review of the application and consequences of ketamine use in RSE. PubMed, Ovid, MEDLINE and PMC were searched for articles describing ketamine treatment for RSE according to a predetermined search strategy and inclusion criteria. The systematic review revealed wide discrepancies in ketamine dosing (infusion maintenance dose range 0.0075-10.5 mg/kg/hour), but good outcomes in medically managed RSE (75% of studies reported moderate or complete seizure control in adults, 62.5% in paediatrics). Additionally, literature review elucidated a potentially causal relationship between prolonged ketamine infusion and both cardiovascular and metabolic dysregulation. Ketamine is effective in RSE by antagonising excitotoxic NMDA receptors. However, there is high variability in ketamine dosing and scarce data on its safety in long-term infusion. Metabolic acidosis and haemodynamic instability associated with the use of long-term, high-dose ketamine infusions must be of concern to clinicians administering ketamine to critically ill patients.

Pentobarbital-induced lactic acidosis following status epilepticus barbiturate coma

We present a rare case of pentobarbital infusion causing propylene glycol-induced lactic acidosis, during refractory status epilepticus treatment in a 66-year-old man without seizure history.

Assessing Propylene Glycol Toxicity in Alcohol Withdrawal Patients Receiving Intravenous Benzodiazepines: A One-Compartment Pharmacokinetic Model

BACKGROUND AND OBJECTIVES

While some case reports indicate that high doses of propylene glycol (PG) may result in metabolic acidosis, there has been no large-scale study that evaluated the risk of metabolic acidosis in patients receiving PG-containing benzodiazepines for acute alcohol withdrawal. This study was undertaken to evaluate the potential toxicity of PG in patients with acute alcohol withdrawal treated with intermittent intravenous bolus doses of diazepam and/or lorazepam.

METHODS

This is a retrospective case study using data collected from 18 randomly selected patients receiving one or both of these medications per a modified Clinical Institute Withdrawal Assessment for Alcohol (CIWA) Class 3 protocol. Plasma levels of PG were estimated using a one-compartment pharmacokinetic model.

RESULTS

Only two patients had an elevated anion gap compared to their baseline value with one also experiencing a significant increase in serum creatinine. No increases in serum osmolarity were noted. Analysis showed that the benzodiazepine dose received was a good predictor of the estimated PG concentration (r = 0.6), but was poorly correlated with the anion gap. No significant correlation was found with the creatinine clearance or serum creatinine. Patients receiving several daily doses were at higher risk of developing an anion gap (r = 0.33), but the estimated maximum PG concentration did not correlate with the anion gap or serum concentration.

CONCLUSION

It does not appear that intermittent bolus administration of intravenous benzodiazepines for alcohol withdrawal influenced renal function or anion gap regardless of number of administered doses, amount of PG received, or the estimated PG concentration.

A Review of Agents for Palliative Sedation/Continuous Deep Sedation: Pharmacology and Practical Applications

Continuous deep sedation at the end of life is a specific form of palliative sedation requiring a care plan that essentially places and maintains the patient in an unresponsive state because their symptoms are refractory to any other interventions. Because this application is uncommon, many providers may lack practical experience in this specialized area and resources they can access are outdated, nonspecific, and/or not comprehensive. The purpose of this review is to provide an evidence- and experience-based reference that specifically addresses those medications and regimens and their practical applications for this very narrow, but vital, aspect of hospice care. Patient goals in a hospital and hospice environments are different, so the manner in which widely used sedatives are dosed and applied can differ greatly as well. Parameters applied in end-of-life care that are based on experience and a thorough understanding of the pharmacology of those medications will differ from those applied in an intensive care unit or other medical environments. By recognizing these different goals and applying well-founded regimens geared specifically for end-of-life sedation, we can address our patients' symptoms in a more timely and efficacious manner.

Trimethoprim/Sulfamethoxazole-Induced Severe Lactic Acidosis: A Case Report and Review of the Literature

Propylene glycol (PG) is used as a solvent in numerous medications, including trimethoprim/sulfamethoxazole (TMP/SMX) and lorazepam, and is metabolized in the liver to lactic acid. Cases of lactic acidosis related to PG toxicity have been described and always involved large doses of benzodiazepines and PG. We present the first case of severe lactic acidosis after a 3-day course of TMP/SMX alone, involving allegedly safe amounts of PG.A 31-year-old female with neurofibromatosis and pilocytic astrocytoma, receiving temozolomide and steroids, was admitted to the intensive care unit for pneumonia and acute respiratory failure requiring intubation. Her initial hemodynamic and acid-base statuses were normal. She was treated with intravenous TMP/SMX for possible Pneumocystis jirovecii pneumonia and was successfully extubated on day 2. On day 3, she developed tachypnea and arterial blood gas analysis revealed a severe metabolic acidosis (pH 7.2, PCO2 19 mm Hg, bicarbonates 8 mEq/L) with anion gap of 25 mEq/L and lactate of 12.1 mmol/L. TMP/SMX was discontinued and the lactate decreased to 2.9 mmol/L within 24 hours while her plasma bicarbonates normalized, without additional intervention. The patient never developed hypotension or severe hypoxia, and her renal and liver functions were normal. No other cause for lactic acidosis was identified and it resolved after TMP/SMX cessation alone, suggesting PG toxicity.Although PG-related lactic acidosis is well recognized after large doses of lorazepam, clinicians should bear in mind that TMP/SMX contains PG as well and should suspect PG toxicity in patients developing unexplained metabolic acidosis while receiving TMP/SMX.

[A first step towards safer sedation and analgesia: A systematic evaluation of outcomes and level of sedation and analgesia in the mechanically ventilated critically ill patient]

INTRODUCTION

Safe analgesia and sedation strategies are necessary in order to avoid under or over sedation, as well as improving the comfort and safety of critical care patients.

OBJECTIVES

To compare and contrast a multidisciplinary protocol of systematic evaluation and management of analgesia and sedation in a group of critical care patients on mechanical ventilation with the usual procedures.

MATERIALS AND METHODS

A cohort study with contemporary series was conducted in a tertiary care medical-surgical ICU February to November during 2013 and 2014. The inclusion criteria were mechanical ventilation ≥ 24h and use of sedation by continuous infusion. Sedation was monitored using the Richmond agitation-sedation scale or bispectral index, and analgesia were measured using the numeric rating scale, or behavioural indicators of pain scale. The study variables included; mechanical ventilation time, weaning time, ventilation support time, artificial airway time, continuous sedative infusion time, daily dose and frequency of analgesic and sedative drug use, hospital stay, and ICU and hospital mortality, Richmond agitation-sedation scale, bispectral index, numeric rating scale, and behavioural indicators of pain scale measurements. Kruskal Wallis and Chi², and a significance of p<.05 were used.

RESULTS

The study included 153 admissions, 75 pre-intervention and 78 post-intervention, with a mean age of 55.7±13 years old, and 67% men. Both groups showed similarities in age, reason for admission, and APACHE. There were non-significant decreases in mechanical ventilation time 4 (1.4-9.2) and 3.2 (1.4-8.1) days, respectively; p= 0.7, continuous sedative infusion time 6 (3-11) and 5 (3-11) days; p= 0.9, length of hospital stay 29 (18-52); 25 (14-41) days; p= 0.1, ICU mortality (8 vs. 5%; p= 0.4), and hospital mortality (10.6 vs. 9.4%: p= 0.8). Daily doses of midazolam and remifentanil decreased 347 (227-479) mg/day; 261 (159-358) mg/day; p= 0.02 and 2175 (1427-3285) mcg/day; 1500 (715-2740) mcg/day; p= 0.02, respectively. There were increases in the use of remifentanil (32% vs. 51%; p= 0.01), dexmedetomidine (0 vs.6%; p= 0.02), dexketoprofen (60 vs. 76%; p= 0.03), and haloperidol (15 vs.28%; p= 0.04). The use of morphine decreased (71 vs. 54%; p= 0.03). There was an increase in the number of measurements and Richmond agitation-sedation scale scores 6 (3-17); 21 (9-39); p< 0.0001, behavioural indicators of pain scale 6 (3-18); 19(8-33); p< 0.001 and numeric rating scale 4 (2-6); 8 (6-17); p< 0.0001.

CONCLUSIONS

The implementation of a multidisciplinary protocol of systematic evaluation of analgesia and sedation management achieved an improvement in monitoring and adequacy of dose to patient needs, leading to improved outcomes.

Development and Evaluation of a Guideline for Monitoring Propylene Glycol Toxicity in Pediatric Intensive Care Unit Patients Receiving Continuous Infusion Lorazepam

OBJECTIVES

To develop and determine the safety of a guideline, by using osmol gap as an indicator of propylene glycol toxicity for pediatric patients receiving continuous infusion lorazepam.

METHODS

From existing adult data, a guideline was developed for the use of continuous infusion lorazepam in pediatric critical care patients with recommendations for using osmol gap as an indicator of propylene glycol toxicity. A retrospective medical chart review was performed of patients receiving continuous infusion lorazepam from February 2012 to September 2012 for whom the guideline was used.

RESULTS

Twenty-one patients received continuous infusion lorazepam for sedation in the pediatric intensive care unit during the 9-month study period for a total of 23 infusions. Eight patients (34.8%) had an osmol gap of ≥ 12 mOsm/kg during lorazepam infusion, and 7 patients (30.4%) did not have an elevated osmol gap at any point during the infusion. Two patients (8.6%) had clinical toxicity as indicated by elevated anion gap or lactate in addition to an osmol gap ≥ 12 mOsm/kg, while no patients experienced clinical toxicity with an osmol gap < 12 mOsm/kg.

CONCLUSIONS

A guideline for the use of lorazepam infusion in pediatric critical care patients was developed and evaluated for safety. Lorazepam continuous infusions appeared to be associated with minimal toxicity in pediatric intensive care unit patients when the osmol gap monitoring guideline was used.

Drug-induced acid-base disorders

The incidence of acid-base disorders (ABDs) is high, especially in hospitalized patients. ABDs are often indicators for severe systemic disorders. In everyday clinical practice, analysis of ABDs must be performed in a standardized manner. Highly sensitive diagnostic tools to distinguish the various ABDs include the anion gap and the serum osmolar gap. Drug-induced ABDs can be classified into five different categories in terms of their pathophysiology: (1) metabolic acidosis caused by acid overload, which may occur through accumulation of acids by endogenous (e.g., lactic acidosis by biguanides, propofol-related syndrome) or exogenous (e.g., glycol-dependant drugs, such as diazepam or salicylates) mechanisms or by decreased renal acid excretion (e.g., distal renal tubular acidosis by amphotericin B, nonsteroidal anti-inflammatory drugs, vitamin D); (2) base loss: proximal renal tubular acidosis by drugs (e.g., ifosfamide, aminoglycosides, carbonic anhydrase inhibitors, antiretrovirals, oxaliplatin or cisplatin) in the context of Fanconi syndrome; (3) alkalosis resulting from acid and/or chloride loss by renal (e.g., diuretics, penicillins, aminoglycosides) or extrarenal (e.g., laxative drugs) mechanisms; (4) exogenous bicarbonate loads: milk-alkali syndrome, overshoot alkalosis after bicarbonate therapy or citrate administration; and (5) respiratory acidosis or alkalosis resulting from drug-induced depression of the respiratory center or neuromuscular impairment (e.g., anesthetics, sedatives) or hyperventilation (e.g., salicylates, epinephrine, nicotine).

Propylene glycol toxicity in children

Propylene glycol (PG) is a commonly used solvent for oral, intravenous, and topical pharmaceutical agents. Although PG is generally considered safe, when used in high doses or for prolonged periods, PG toxicity can occur. Reported adverse effects from PG include central nervous system (CNS) toxicity, hyperosmolarity, hemolysis, cardiac arrhythmia, seizures, agitation, and lactic acidosis. Patients at risk for toxicity include infants, those with renal or hepatic insuficiency, epilepsy, and burn patients receiving extensive dermal applications of PG containing products. Laboratory monitoring of PG levels, osmolarity, lactate, pyruvate, bicarbonate, creatinine, and anion gap can assist practitioners in making the diagnosis of PG toxicity. Numerous studies and case reports have been published on PG toxicity in adults. However, very few have been reported in pediatric patient populations. A review of the literature is presented.

Severe propylene glycol toxicity secondary to use of anti-epileptics

Propylene glycol toxicity presenting as high anion gap metabolic acidosis and osmolar gap has been extensively reported in literature, and most of them are secondary to intravenous lorazepam infusion. However, propylene glycol is used as a solvent in a number of medications that are frequently utilized in critical care setting, and hence one should be aware that the toxicity is possible from a variety of medication. Phenobarbital and phenytoin are one of those, and we hereby report a novel case of propylene glycol toxicity secondary to phenobarbital and phenytoin infusion in a patient with refractory status epilepticus. Furthermore, our patient had end-stage renal disease, which we think could have been an important precipitating factor for the toxicity. Because most of the symptoms from propylene glycol toxicity can mimic sepsis-which is very common in critical care unit patients-this life threatening scenario could be easily missed. Regular monitoring of osmolar gap is an easily available intervention in the at risk patients.

Risk assessment of neonatal excipient exposure: lessons from food safety and other areas

Newborn babies can require significant amounts of medication containing excipients intended to improve the drug formulation. Most medicines given to neonates have been developed for adults or older children and contain excipients thought to be safe in these age groups. Many excipients have been used widely in neonates without obvious adverse effects. Some excipients may be toxic in high amounts in which case they need careful risk assessment. Alternatively, it is conceivable that ill-founded fears about excipients mean that potentially useful medicines are not made available to newborn babies. Choices about excipient exposure can occur at several stages throughout the lifecycle of a medicine, from product development through to clinical use. Making these choices requires a scalable approach to analysing the overall risk. In this contribution we examine these issues.

Clinical practice guidelines for the management of pain, agitation, and delirium in adult patients in the intensive care unit

OBJECTIVE

To revise the "Clinical Practice Guidelines for the Sustained Use of Sedatives and Analgesics in the Critically Ill Adult" published in Critical Care Medicine in 2002.

METHODS

The American College of Critical Care Medicine assembled a 20-person, multidisciplinary, multi-institutional task force with expertise in guideline development, pain, agitation and sedation, delirium management, and associated outcomes in adult critically ill patients. The task force, divided into four subcommittees, collaborated over 6 yr in person, via teleconferences, and via electronic communication. Subcommittees were responsible for developing relevant clinical questions, using the Grading of Recommendations Assessment, Development and Evaluation method (http://www.gradeworkinggroup.org) to review, evaluate, and summarize the literature, and to develop clinical statements (descriptive) and recommendations (actionable). With the help of a professional librarian and Refworks database software, they developed a Web-based electronic database of over 19,000 references extracted from eight clinical search engines, related to pain and analgesia, agitation and sedation, delirium, and related clinical outcomes in adult ICU patients. The group also used psychometric analyses to evaluate and compare pain, agitation/sedation, and delirium assessment tools. All task force members were allowed to review the literature supporting each statement and recommendation and provided feedback to the subcommittees. Group consensus was achieved for all statements and recommendations using the nominal group technique and the modified Delphi method, with anonymous voting by all task force members using E-Survey (http://www.esurvey.com). All voting was completed in December 2010. Relevant studies published after this date and prior to publication of these guidelines were referenced in the text. The quality of evidence for each statement and recommendation was ranked as high (A), moderate (B), or low/very low (C). The strength of recommendations was ranked as strong (1) or weak (2), and either in favor of (+) or against (-) an intervention. A strong recommendation (either for or against) indicated that the intervention's desirable effects either clearly outweighed its undesirable effects (risks, burdens, and costs) or it did not. For all strong recommendations, the phrase "We recommend …" is used throughout. A weak recommendation, either for or against an intervention, indicated that the trade-off between desirable and undesirable effects was less clear. For all weak recommendations, the phrase "We suggest …" is used throughout. In the absence of sufficient evidence, or when group consensus could not be achieved, no recommendation (0) was made. Consensus based on expert opinion was not used as a substitute for a lack of evidence. A consistent method for addressing potential conflict of interest was followed if task force members were coauthors of related research. The development of this guideline was independent of any industry funding.

CONCLUSION

These guidelines provide a roadmap for developing integrated, evidence-based, and patient-centered protocols for preventing and treating pain, agitation, and delirium in critically ill patients.

Current sedation practices: lessons learned from international surveys

Limitations are inherent to surveys. Most surveys have low response rates, which raises the issue of responder bias. Another limitation of self-report surveys stems from the possible differences between stated and actual practice. That is, what physicians report that they do in surveys often contrasts significantly with what they do in observational studies, as highlighted by the Canadian surveys conducted in 2002 and 2008. Some surveys report estimates provided by ICU nurse managers or physician directors, potentially resulting in inaccurate estimates or data reflecting the individuals practice rather than the entire ICU. Surveys may not reflect how different specialists practice; for example, the German surveys collected data only in ICUs run by anesthesiologists.Notwithstanding these limitations, surveys provide a wealth of information on current practice and determinants of practice, and serve as a useful tool to guide future research and educational interventions. The authors identified substantial international variation in the use of sedative and analgesic drugs, and marked changes over the last 10 years. Overall, there is a trend toward lighter sedation, along with a shift from benzodiazepines toward propofol, and from morphine toward fentanyl and remifentanil. Despite the publication of numerous studies and guidelines for sedation and analgesia, actual practice differs from recommended practice, suggesting that the impact of clinical trials and guidelines on physician practice is quite low. It is clear that there remain substantial barriers to the incorporation of sedation scales, protocols,and daily interruption into routine ICU care.

Novel nephrotoxins

Drug and xenobiotic toxicity is an important cause of kidney injury, especially in vulnerable patients. Nephrotoxic syndromes include functional disorders; vascular injury, such as thrombotic microangiopathy; glomerular injury resulting in nephrotic syndrome or glomerulonephritis; acute tubular necrosis; acute interstitial nephritis; and crystalopathy/nephrolithiasis. Recently reported nephrotoxins are reviewed in the context of these syndromes of kidney injury.

Toxicology today: what you need to know now

Clinicians are frequently confronted with toxicological emergencies and challenged with the task of correctly identifying the possible agents involved and providing appropriate treatments. In this review article, we describe the epidemiology of overdoses, provide a practical approach to the recognition and diagnosis of classic toxidromes, and discuss the initial management strategies that should be considered in all overdoses. In addition, we evaluate some of the most common agents involved in poisonings and present their respective treatments. Recognition of toxidromes with knowledge of indications for antidotes and their limitations for treating overdoses is crucial for the acute care of poisoned patients.

Adverse drug events associated with the use of analgesics, sedatives, and antipsychotics in the intensive care unit

As critically ill patients frequently receive analgesics, sedatives, and antipsychotics to optimize patient comfort and facilitate mechanical ventilation, adverse events associated with the use of these agents can affect all organ systems and result in substantial morbidity and mortality. Although many of these adverse effects are common pharmacologic manifestations of the agent, and therefore frequently reversible, others are idiosyncratic and thus unexpected. The critically ill are more susceptible to adverse drug events than nonintensive care unit patients due to the high doses and long periods for which each of these agents are often administered, the frequent use of intravenous formulations that contain adjuvants that may lead to toxicity in some instances, and the high prevalence of end-organ dysfunction that affects the pharmacokinetic and pharmacodynamic response to therapy. This paper will review the most common and serious adverse drug events reported to occur with the use of sedatives, analgesics, and antipsychotics in the intensive care unit; highlight the pharmacokinetic, pharmacodynamic, and pharmacogenetic factors that can influence analgesic, sedative, and antipsychotic response and safety in the critically ill; and identify strategies that can be used to minimize toxicity with these agents.

Are excipients really inert ingredients? A review of adverse reactions to excipients in oral dermatologic medications in Canada

BACKGROUND

Whereas several literature reviews have discussed the role of excipients in drug-related reactions, no article has focused specifically on those found in oral dermatologic medications.

METHODS

The Compendium of Pharmaceuticals and Specialties (CPS) was used to reference the inert ingredients found in oral dermatologic medications. An extensive literature review was subsequently conducted using PubMed and MEDLINE to document adverse reactions to these excipients.

RESULTS

Sixty-three oral dermatologic medications were reviewed. Lactose was commonly used as a filler. Several medications indicated that they were dye, tartrazine, or gluten free. Three medications were found to contain soybean oil and one was found to contain peanut oil.

CONCLUSIONS

Although there are documented reactions to excipients in other products in the literature, few reports outline reactions to excipients in oral dermatologic medications. Whether this low frequency is accurate or whether it is due to a lack of reporting remains unknown. If the latter reasoning is correct, dermatologists must be more aware of these possible reactions. This article serves as a reference guide for dermatologists to aid in prescribing medications to individuals with known sensitivities and to assist in working up patients with suspected reactions to inert ingredients.

Severe lactic acidosis after an iatrogenic propylene glycol overdose

Propylene glycol is a diluent found in many intravenous and oral drugs, including phenytoin, diazepam, and lorazepam. Propylene glycol is eliminated from the body by oxidation through alcohol dehydrogenase to form lactic acid. Under normal conditions, the body converts lactate to pyruvate and metabolizes pyruvate through the Krebs cycle. Lactic acidosis has occurred in patients, often those with renal dysfunction, who were receiving prolonged infusions of drugs that contain propylene glycol as a diluent. We describe a 50-year-old man who experienced severe lactic acidosis after receiving an accidental overdose of lorazepam, which contains propylene glycol. The patient was acutely intoxicated, with a serum ethanol concentration of 406 mg/dl. He had choked on a large piece of meat and subsequently experienced pulseless electrical activity with ventricular fibrillation cardiac arrest. He was brought to the emergency department; within 2 hours, he was admitted to the intensive care unit for initiation of the hypothermia protocol. The patient began to experience generalized tonic-clonic seizures 12 hours later, which resolved after several boluses of lorazepam. A lorazepam infusion was started; however, it was inadvertently administered at a rate of 2 mg/minute instead of the standard rate of 2 mg/hour. Ten hours later, the administration error was recognized and the infusion stopped. The patient's peak propylene glycol level was 659 mg/dl, pH 6.9, serum bicarbonate level 5 mEq/L, and lactate level 18.6 mmol/L. Fomepizole was started the next day and was continued until hospital day 3. Continuous renal replacement therapy was started and then replaced with continuous venovenous hemofiltration (CVVH) for the remainder of the hospital stay. The patient's acidosis resolved by day 3, when his propylene glycol level had decreased to 45 mg/dl. Fomepizole was discontinued, but the patient's prognosis was poor (anoxic brain injury); thus care was withdrawn and the patient died. Although the patient's outcome was death, his lactic acidosis was treated successfully with fomepizole and CVVH. Clinicians should be aware that an iatrogenic overdose of lorazepam may result in severe propylene glycol toxicity, which may be treated with fomepizole and CVVH.

Treatment of lactic acidosis: appropriate confusion

BACKGROUND

Lactic acidosis (LA) is common in hospitalized patients and is associated with poor clinical outcomes. There have been major recent advances in our understanding of lactate generation and physiology. However, treatment of LA is an area of controversy and uncertainty, and the use of agents to raise pH is not clearly beneficial.

AIM AND METHODS

We reviewed animal and human studies on the pathogenesis, impact, and treatment of LA, published in the English language and available through the PubMed/MEDLINE database. Our aim was to clarify the physiology of the generation of LA, its impact on outcomes, and the different treatment modalities available. We also examined relevant data regarding LA induced by medications commonly prescribed by hospitalists: biguanides, nucleoside analog reverse-transcriptase inhibitors (NRTIs), linezolid, and lorazepam.

RESULTS/CONCLUSIONS

Lactic acid is a marker of tissue ischemia but it also may accumulate without tissue hypoperfusion. In the latter circumstance, lactic acid accumulation may be an adaptive mechanism-a novel possibility quite in contrast to the traditional view of lactic acid as only a marker of tissue ischemia. Studies on the treatment of LA with sodium bicarbonate or other buffers fail to show consistent clinical benefit. Severe acidemia in the setting of LA is a particularly poorly studied area. In the settings of medication-induced LA, optimal treatment, apart from prompt cessation of the offending agent, is still unclear.

Propylene glycol accumulation in critically ill patients receiving continuous intravenous lorazepam infusions

BACKGROUND

Lorazepam is recommended by the Society of Critical Care Medicine as the preferred agent for sedation of critically ill patients. Intravenous lorazepam contains propylene glycol, which has been associated with toxicity when high doses of lorazepam are administered.

OBJECTIVE

To evaluate the accumulation of propylene glycol in critically ill patients receiving lorazepam by continuous infusion and determine factors associated with propylene glycol concentration.

METHODS

A 6-month, retrospective, safety assessment was conducted of adults admitted to the medical intensive care unit who were receiving lorazepam by continuous infusion for 12 hours or more. Propylene glycol serum concentrations were obtained 24-48 hours after continuous-infusion lorazepam was initiated and every 3-5 days thereafter. Propylene glycol accumulation was defined as concentrations of 25 mg/dL or more. Groups with and without propylene glycol accumulation were compared and factors associated with propylene glycol concentration were determined using multivariate correlation regression analyses.

RESULTS

Forty-eight propylene glycol serum samples were obtained from 33 patients. Fourteen (42%) patients had propylene glycol accumulation, representing 23 (48%) serum samples. Univariate analyses showed the following factors were related to propylene glycol accumulation: baseline renal dysfunction, presence of alcohol withdrawal, sex, age, Acute Physiology and Chronic Health Evaluation (APACHE II) score, rate of lorazepam continuous infusion, and 24-hour lorazepam dose. Multivariate linear regression modeling demonstrated that propylene glycol concentration was strongly associated with the continuous infusion rate and 24-hour dose (adjusted r(2) > or = 0.77; p < 0.001). Independent correlation analyses showed that these 2 variables were so strongly associated with propylene glycol concentration (r(2) > or = 0.71; p < 0.001) that they alone predicted propylene glycol concentration. Seven (21%) patients developed renal dysfunction after continuous-infusion lorazepam was initiated, but associated causes were indeterminable. Other possible propylene glycol-associated adverse effects were not observed.

CONCLUSIONS

The continuous infusion rate and cumulative 24-hour lorazepam dose are strongly associated with and independently predict propylene glycol concentrations. Despite the absence of confirmed propylene glycol-associated adverse effects, clinicians should be aware that propylene glycol accumulation may occur with continuous-infusion lorazepam.

Current sedation practices: lessons learned from international surveys

Patient outcomes are significantly influenced by the choice of sedative and analgesic agents, the presence of over- or undersedation, poor pain control, and delirium. Individualized sedation management using sedation assessment tools, sedation protocols, and daily sedative interruption can improve clinical outcomes. Despite the publication of randomized trials and numerous guidelines, the uptake of proven strategies into routine practice can be slow. Surveys of clinicians' self-reported practice and prospective practice audits characterize sedation and analgesia practices and provide directions for education and future research. The objective of this review is to present the findings of surveys and practice audits, evaluating the management of sedation and analgesia in mechanically ventilated adults in the intensive care unit, and to summarize international critical care sedation practices.

Exposure to the pharmaceutical excipients benzyl alcohol and propylene glycol among critically ill neonates

OBJECTIVE

To document neonatal exposures to the potentially harmful pharmaceutical excipients benzyl alcohol (BA) and propylene glycol (PG) present in parenteral medications routinely administered in the intensive care unit.

DESIGN

Retrospective, observational study.

SETTING

Neonatal and pediatric intensive care units of a tertiary care, university hospital.

PATIENTS

Randomly selected sample of 170 episodes of exposure to parenteral medications containing BA (n = 88) or PG (n = 82).

MEASUREMENTS

We identified all medication sources of BA or PG administered to study neonates during hospitalization, and calculated cumulative doses (mg/kg/day and mg/day) of BA or PG received as a result of exposure to those medications.

MAIN RESULTS

We observed a wide range in the cumulative excipient dose received by neonates. Median (range) cumulative dose was 4.5 mg/kg/day (0.6-319.5 mg/kg/day) for BA, and 204.9 mg/kg/day (17.3-9472.7 mg/kg/day) for PG. Patients who received medications via continuous infusion received significantly higher excipient doses than patients who received medications intermittently (p < 0.0001). In this subset of patients, median cumulative excipient doses (BA, 106.3 mg/kg/day and PG, 4554.5 mg/kg/day) were approximately 21 and 180 times the acceptable daily intakes of BA and PG (5 and 25 mg/kg/day), respectively, and exceeded the doses above which toxicity has been reported in infants. No significant correlation between duration of medication administration and cumulative excipient exposure was identified for BA or PG. Midazolam and lorazepam were involved in over two-thirds of BA and PG exposures, respectively.

CONCLUSIONS

Critically ill neonates, especially those receiving medications by continuous infusion, are at risk of being exposed to BA and PG at potentially toxic doses during routine medication administration. Given the serious adverse reactions known to be associated with BA and PG, future studies are warranted to determine the clinical consequences associated with this degree of excipient exposure.

Hyperosmolar, increased-anion-gap metabolic acidosis and hyperglycemia after etomidate infusion

Hyperosmolar increased-anion-gap metabolic acidosis without hyperglycemia has been reported after infusions of etomidate and other medications containing propylene glycol. We report a case of this biochemical abnormality with severe hyperglycemia. Cessation of the etomidate infusion along with other supportive measures resulted in prompt resolution of the metabolic acidosis and hyperglycemia.

A prospective evaluation of propylene glycol clearance and accumulation during continuous-infusion lorazepam in critically ill patients

Propylene glycol is a commonly used diluent in several pharmaceutical preparations, including the sedative lorazepam. Fifty critically ill patients receiving continuous-infusion lorazepam for a minimum of 36 hours were prospectively evaluated to determine the extent of propylene glycol accumulation over time, characterize propylene glycol clearance in the presence of critical illness, and develop a pharmacokinetic model that would predict clearance based on patient-specific clinical, laboratory, and demographic factors. In this cohort, the median lorazepam infusion rate was 2.1 mg/h (0.5-18). Propylene glycol concentration correlated poorly with osmolality, osmol gap, and lactate. In all, 8 patients (16%) had significant propylene glycol accumulation (>25mg/dL). When propylene glycol concentrations were >25 mg/dL, the median lorazepam infusion rate before sample collection was higher, 6.4 (1.9-11.3) versus 2.0 (0.5-7.4) mg/h (P =.0003). A linear first-order model with interoccasion variability on clearance adjusted for total body weight and Acute Physiology and Chronic Health Evaluation II score predicted propylene glycol concentration.

Propylene glycol-induced lactic acidosis in a patient receiving continuous infusion pentobarbital

OBJECTIVE

To report a case of probable propylene glycol (PG) toxicity in a patient receiving continuous infusion of pentobarbital for refractory status epilepticus.

CASE SUMMARY

A 59-year-old woman with a declining mental status was admitted to the intensive care unit for management of status epilepticus. After failing to achieve the therapeutic endpoint of electroencephalogram burst suppression with a continuous infusion of propofol, the sedative regimen was changed to continuous infusion of pentobarbital. The patient received a loading dose of 450 mg (5 mg/kg), and the maintenance infusion was titrated to a dose of 10 mg/kg/h to achieve burst suppression. Twelve hours after the pentobarbital infusion was started, the patient developed an anion gap metabolic acidosis, elevated serum lactate level, hyperosmolality, and increased osmolal gap. The pentobarbital infusion was discontinued, and the patient's acidosis and hyperosmolality resolved.

DISCUSSION

Pentobarbital contains 40% v/v of PG, which was thought to be a potential source of the patient's metabolic derangements. Reports of toxicity with drugs containing PG, particularly intravenous lorazepam, have been well described in the literature. What we describe, however, is one of few reports involving intravenous pentobarbital. The Naranjo probability scale supports a probable drug-related adverse event in our patient.

CONCLUSIONS

PG toxicity is a potential complication associated with intravenous pentobarbital. Practitioners should be aware of the PG content of pentobarbital and should be familiar with the signs and symptoms associated with PG toxicity.

[ICU-acquired neuromyopathy, delirium and sedation in intensive care unit]

ICU-acquired neuromyopathy (NMAR) and delirium are the two most frequent and severe neurological complications of intensive care medicine. Their mechanisms still remain to be elucidated. The objective of this review is to address the potential role of sedation in occurrence of these complications. There is no evidence that sedation is involved in NMARs. However, the hypothesis that muscle inactivity induced by sedation fosters NMAR is an argument to discontinue or reduce sedatives infusion whenever possible. It is also recommended not to administer propofol more than 48 h at an infusion rate above 5 mg/kg per hour in patients with systemic inflammatory response syndrome, because of the risk of propofol infusion syndrome, which includes notably rhabdomyolysis. The relationship between delirium and sedation are controversial because in most studies, patients were considered delirious though being still sedated and multivariate analysis was lacking. One study showed that lorazepam given continuously was an independent risk factor for daily transition to delirium 24 h later with a 20% increase risk of every unit dose (expressed as log(e)mg). The impact of deepness, daily interruption or titration of sedation on the prevalence of delirium has never been assessed but it seems that deep sedation has to be avoided.

Medication-related complications in the trauma patient

Trauma patients are twice as likely to have adverse reactions to medication as nontrauma patients. The need for medication in trauma patients is high. Surgery is often necessary, and immunosuppression and hypercoagulability may be present. Adverse drug events can be caused in part by altered pharmacokinetics, drug interactions, and polypharmacy. Medications may also have serious long-term adverse effects, which must be considered. It is not the purpose of this review article to discuss all adverse effects of all medications. This article will discuss the more common adverse effects of medications for trauma patients in the acute care setting, in the following categories: pain control, sedation, antibiotics, seizure prophylaxis in head trauma, atrial fibrillation, deep vein thrombosis and pulmonary embolism prophylaxis, hemodynamic support, adrenal insufficiency, factor VIIa.