Sedative-Hypnotic Agents That Impact Gamma-Aminobutyric Acid Receptors: Focus on Flunitrazepam, Gamma-Hydroxybutyric Acid, Phenibut, and Selank.

There are many nonopioid central nervous system depressant substances that share a gamma-aminobutyric acid (GABA) receptor-related mechanism of action. These sedatives-hypnotics can be indicated to treat anxiety, seizures, depression, and insomnia but are also used as substances of abuse and used to facilitate sexual assault. Barbiturates, methaqualone, and glutethimide were among the first type A GABA receptor-mediated sedative-hypnotics. Their clinical use was limited for most indications by serious adverse events and strong abuse potential but continue to be used illicitly around the world. The benzodiazepines supplanted barbiturates for most indications because they were less likely to cause severe adverse events in monotherapy. Flunitrazepam is a newer benzodiazepine that is preferentially used recreationally and to facilitate sexual assault. Flunitrazepam has greater potency and higher affinity for the type A GABA receptor than most benzodiazepines. Gamma-hydroxybutyric acid is sought illicitly for its hypnotic, euphoric and anabolic effects as well as to facilitate sexual assault. When any of these GABAergic drugs are used in high doses or with other sedative hypnotic agents, respiratory depression, coma, and death have occurred. Chronic use of these GABAergic drugs can lead to significant withdrawal syndromes. Phenibut and selank are poorly studied Russian drugs with GABAergic mechanisms that are inexplicably sold to US consumers as dietary supplements. Poison control center calls regarding phenibut have increased substantially over the past 5 years. Desired euphoriant effects account for the recreational and illicit use of many GABA-modulating agents. However, illicit use can lead to significant toxicities related to abuse, dependence, and subsequent withdrawal syndromes. Significant evaluation of developing agents with GABA properties should be conducted to determine abuse potential before public access ensues.

Paracetamol overdose in the newborn and infant: a life-threatening event.

PURPOSE: Paracetamol is the only drug recommended to treat fever in neonates. At recommended doses, paracetamol has not been associated with liver injury in neonates, while hepatotoxicity may occur after intake of a single high dose or multiple excessive doses. The aim of this narrative review is to critically analyze and summarize the available literature on newborns and infants exposed to supratherapeutic doses of paracetamol, with special focus on their clinical features, outcome, and management. METHODS: The PubMed, SCOPUS, and Google Scholar search engines were used to collect data, without time limitation. The following keywords were used: paracetamol/acetaminophen, overdose, hepatotoxicity, N-acetylcysteine, newborn, infant. RESULTS: The literature search identified a total of 27 case reports, a number of review articles, and few other relevant publications. Neonatal poisoning from paracetamol resulted from transplacental drug transfer after maternal overdose in some published cases, while it was the consequence of medication errors in other cases. Newborns and infants who have received a single overdose and have paracetamol concentrations below the Rumack-Matthew nomogram limits are at low risk of serious hepatic damage, while those who have recently ingested more than one supratherapeutic dose of paracetamol should be managed with caution. The treatment of choice for paracetamol poisoning is N-acetylcysteine, a specific antidote which reduces paracetamol hepatotoxic effects. N-Acetylcysteine should be given according to specific regimens through weight-based dosing tables. CONCLUSIONS: Caution should be used when paracetamol is administered to the newborn. In the event of an overdose, careful patient monitoring and personalization of post-overdose procedures are recommended.

First-Line Vasopressor and Mortality Rates in ED Patients with Acute Drug Overdose.

INTRODUCTION: While emergency department (ED) visits for acute drug overdose are at an all-time high, the importance of vasopressors to treat circulatory shock in this patient population remains unclear. This study investigated the association between first-line vasopressor and mortality, for both push-dose and infusion, in this patient population. METHODS: From a prospective cohort of consecutive ED patients with drug overdose at two urban teaching centers over 5 years, we performed a secondary data analysis of patients with circulatory shock, defined as hypotension requiring either vasopressors, high-dose insulin euglycemia therapy, or both. The first-line vasopressor (push-dose and infusion) was analyzed for associations with the primary outcome (in-hospital mortality) and secondary outcomes (24-hour mortality, ICU LOS). Subgroup analysis of beta-/calcium-channel blocker overdose was performed to evaluate impact of antidotal therapies. Data analysis included multivariable regression. RESULTS: Fifty-five patients with circulatory shock were analyzed, in whom there was 20% 24-hour mortality, 42% in-hospital mortality, 730-minute mean vasopressor duration, and 53.4-hour median ICU LOS. On multivariable analysis, there was significantly decreased adjusted odds of in-hospital mortality with first-line push-dose phenylephrine (aOR 0.06, CI 0.01-0.55), and significantly increased adjusted odds of in-hospital mortality with first-line push-dose epinephrine (aOR 60.8, CI 6.1-608). Of the first-line infusions, norepinephrine had the lowest odds of in-hospital mortality (aOR 0.80, CI 0.2-3.1). CONCLUSIONS: In ED patients with undifferentiated drug overdose and circulatory shock, the first-line vasopressor is associated with in-hospital mortality. First-line push-dose phenylephrine was associated with the lowest odds of in-hospital mortality. Future randomized studies are warranted for validation.

Low dose Intralipid resuscitation improves survival compared to ClinOleic in propranolol overdose in rats.

BACKGROUND: Medication overdose is a prevalent issue and despite mixed reports of efficacy, the use of intravenous lipid emulsions, notably Intralipid®, for the management of toxicity from lipid-soluble drugs is becoming increasingly prevalent. Whether alternative lipid emulsion formulations have similar efficacy for resuscitation compared to Intralipid is not known. Here, we compared the efficacy of Intralipid and ClinOleic® for resuscitation following overdose with the lipid-soluble beta-adrenergic antagonist propranolol. METHODS: Male Sprague-Dawley rats (age 3-4 months) were anesthetized with isoflurane and instrumented for direct hemodynamic assessments. In Study One, rats (n = 22) were pre-treated with Intralipid 20% (n = 12) or ClinOleic 20% (n = 10) to determine whether the hemodynamic effects of propranolol could be prevented. In Study Two, rats were randomly assigned to Intralipid 20% (1, 2, or 3 mL/kg IV, n = 21) or ClinOleic 20% (1, 2, or 3 mL/kg IV, n = 20) resuscitation groups following propranolol overdose (15 mg/kg IV). In Study Three the effect of Intralipid 20% (1 mL/kg IV, n = 3) and ClinOleic 20% (1 mL/kg IV, n = 3) in the absence of propranolol was investigated. The primary endpoint in all studies was survival time (up to a maximum of 120 minutes), and secondary endpoints were time to achieve 50%, 75%, and 90% of baseline hemodynamic parameters. RESULTS: In Study One, pre-treatment with Intralipid prior to propranolol administration resulted in prolonged survival compared to pre-treatment with ClinOleic at low doses (1 mL/kg; P = 0.002), but provided no benefit at higher doses (3 mL/kg; P = 0.95). In Study Two, Intralipid conferred a survival advantage over ClinOleic, with 18/21 rats surviving 120 minutes in the Intralipid group and only 4/20 survivors in the ClinOleic group (P<0.0001). Median survival times (with interquartile ranges) for rats treated with Intralipid, and ClinOleic, and saline were 120 (80.5-120) min, 21.5 (3.25-74.5) min, and 1 (0.25-2.5) min respectively (P<0.001). Only 3/21 rats in the Intralipid group survived less than 30 minutes, whereas 12/20 ClinOleic treated rats had survival times of less than 30 minutes. The number of rats achieving 75%, and 90% of baseline mean arterial pressure was also greater in the Intralipid group (P<0.05 for both values). Treatment in Study Three did not alter survival times. CONCLUSIONS: Low-dose Intralipid (1, 2, or 3 mL/kg IV) confers a survival advantage up to 120 minutes post-propranolol overdose (the end-point of the experiment) and better hemodynamic recovery compared to ClinOleic (1, 2, or 3 mL/kg IV) in rats with propranolol overdose. As health care centres choose alternate intravenous lipid emulsions, limited availability of Intralipid could impact efficacy and success of overdose treatment for lipid-soluble drugs.

Severe beta blocker and calcium channel blocker overdose: Role of high dose insulin.

A 54-year-old female presented after taking an overdose of an unknown amount of hydrochlorothiazide, doxazocin, atenolol and amlodipine. She was initially refractory to treatment with conventional therapy (intravenous fluids, activated charcoal, glucagon 5 mg followed with glucagon drip, calcium gluconate 10%, and atropine). Furthermore, insulin at 4 U/kg was not effective in improving her hemodynamics. Shortly after high dose insulin was achieved with 10 U/kg, there was dramatic improvement in hemodynamics resulting in three of five vasopressors being weaned off in 8 h. She was subsequently off all vasopressors after six additional hours. The role of high dose insulin has been documented in prior cases, however it is generally recommended after other conventional therapies have failed. However, there are other reports that suggest it as initial therapy. Our patient failed conventional therapies and responded well only with maximum dose of insulin. Physicians should consider high dose insulin early in severe beta blocker or calcium channel blocker overdose for improvement in hemodynamics. This leads to early discontinuation of vasopressors. It is important that emergency physicians be aware of the beneficial effects of high dose insulin when initiated early as opposed to waiting for conventional therapy to fail; as these patients often present first to the emergency department. Early initiation in the emergency department can be beneficial in these patients.

Clinical Potential of an Enzyme-based Novel Therapy for Cocaine Overdose.

It is a grand challenge to develop a truly effective medication for treatment of cocaine overdose. The current available, practical emergence treatment for cocaine overdose includes administration of a benzodiazepine anticonvulsant agent (e.g. diazepam) and/or physical cooling with an aim to relieve the symptoms. The inherent difficulties of antagonizing physiological effects of drugs in the central nervous system have led to exploring protein-based pharmacokinetic approaches using biologics like vaccines, monoclonal antibodies, and enzymes. However, none of the pharmacokinetic agents has demonstrated convincing preclinical evidence of clinical potential for drug overdose treatment without a question mark on the timing used in the animal models. Here we report the use of animal models, including locomotor activity, protection, and rescue experiments in rats, of drug toxicity treatment with clinically relevant timing for the first time. It has been demonstrated that an efficient cocaine-metabolizing enzyme developed in our previous studies can rapidly reverse the cocaine toxicity whenever the enzyme is given to a living rat, demonstrating promising clinical potential of an enzyme-based novel therapy for cocaine overdose as a successful example in comparison with the commonly used diazepam.

A Retrospective Study of Clinical Effects of Powdered Caffeine Exposures Reported to Three US Poison Control Centers.

INTRODUCTION: Anhydrous caffeine, often sold on the Internet as a powdered caffeine product, is sold as "pure caffeine" to be used as an additive to beverages and has also been used as an ingredient in energy supplement products. METHODS: This is a retrospective multiple-poison center chart review of calls regarding powdered caffeine to poison centers covering Oregon, Alaska, Guam, Washington, and Utah between January 1, 2013 and June 30, 2015. RESULTS: There were 40 calls to three poison centers over 30 months for powdered caffeine exposure. The majority of patients were over age 19 (52.5 %; 21/40) and male (70 %; 28/40). Sixty percent (24/40) of the patients were symptomatic but only 10 % (4/40) required admission; 52.5 % (21/40) of the patient calls were for inadvertent overdose of powdered caffeine; one patient overdosed in a self-harm attempt. DISCUSSION: Powdered caffeine calls to three poison centers during a 30-month study period were rare, and severe caffeine toxicity due to exposure was found in few patients. The majority of symptoms were reported after an inadvertent powdered caffeine overdose. CONCLUSIONS: An analysis of calls to three poison centers for powdered caffeine found that exposures were uncommon, but did result in toxicity, and highlighted that the lack of clear dosing instructions on product packaging may place patients at risk of inadvertent overdose.

The Changing Drug Culture: Use and Misuse of Cognition-Enhancing Drugs.

There has been an increase in diagnoses of attention-deficit/hyperactivity disorder (ADHD), with approximately 9% of American children now diagnosed, and a concomitant increase in the use of stimulants (eg, amphetamines, methylphenidate) to manage ADHD. Nonstimulant drugs (eg, atomoxetine, guanfacine, clonidine) also are used, but most patients are treated with stimulants. All of these drugs are effective for management of ADHD, and, overall, use in childhood does not seem to increase the risk of substance abuse later in life. However, widespread use has resulted in prescription stimulants being diverted for nonmedical uses, particularly by high school and college students seeking cognitive enhancement for improved academic performance. Studies of ADHD drugs for improving cognition in patients without ADHD have mixed results, and any improvements appear to be modest and short-term. Other substances also are used for cognitive enhancement. Drugs for Alzheimer disease are being used for mild cognitive impairment, though there is no evidence that they are effective. Creatine may have mild cognition-enhancing properties, but study results often are confounded by the addition of exercise, which by itself is thought to improve cognition. There is no evidence that other supplements, such as vitamins and omega-3 fatty acids, improve cognitive function.

Ritualistic Use of Ayahuasca versus Street Use of Similar Substances Seized by the Police: A Key Factor Involved in the Potential for Intoxications and Overdose?

The ritualistic use of ayahuasca is becoming a global phenomenon. This beverage contains a combination of monoamine oxidase inhibitors (harmine, harmaline, and tetrahydroharmine) and N,N-dimethyltryptamine, the main substance responsible for its visionary effect. The recreational use of similar alkaloids and N,N-dimethyltryptamine has increased in recent years, mainly because of their hallucinogenic effects. In the present study, the concentrations of psychoactive alkaloids in three powder samples seized by the São Paulo State Police and nine ayahuasca aqueous extracts were analyzed by HPLC-DAD in an attempt to distinguish between illicit drugs and the religious beverage. The alkaloids detected (µg/mL) in the ayahuasca aqueous extracts were N,N-dimethyltryptamine (402-2070.3), harmaline (27.5-181.3), harmine (294.5-2893.8), and tetrahydroharmine (849.5-2052.5), whereas, of the three powder samples, one contained only N,N-dimethyltryptamine (82% and 2% w/w, respectively) while the other contained only harmaline (16%, w/w) and harmine (12%, w/w). The ritualistic use of ayahuasca involves oral intake and the probability of overdose is minimized by serotonergic stimulation of vagal pathways, leading to vomiting and diarrhea. In contrast, the recreational use of N,N-dimethyltryptamine involves consumption mainly by smoking or inhalation, both of which markedly increase its bioavailability and the potential for intoxications.

Massive Atenolol, Lisinopril, and Chlorthalidone Overdose Treated with Endoscopic Decontamination, Hemodialysis, Impella Percutaneous Left Ventricular Assist Device, and ECMO.

BACKGROUND: Overdose of cardiovascular medications is increasingly associated with morbidity and mortality. We present a case of substantial atenolol, chlorthalidone, and lisinopril overdose treated by multiple modalities with an excellent outcome. CONCLUSION: Aggressive medical intervention did not provide sufficient hemodynamic stability in this patient with refractory cardiogenic and distributive shock. Impella® percutaneous left ventricular assist device and extracorporeal membrane oxygenation provided support while the effects of the overdose subsided. We present concentrations demonstrating removal of atenolol with continuous venovenous hemodiafiltration. This is the first report of esophagogastroduo denoscopy decontamination of this overdose with a large pill fragment burden.

Continuous venovenous hemodiafiltration along with charcoal hemoperfusion for the management of life-threatening lercanidipine and amlodipine overdose.

Overdose with calcium channel blockers is uncommon, but is associated with high mortality. The management includes fluid resuscitation, calcium gluconate, glucagon, vasopressors, and high-dose insulin-euglycemia therapy. We describe a rare case of massive overdose of lercanidipine with shock, refractory to conventional therapies and multi-organ failure. Charcoal hemoperfusion with continuous venovenous hemodiafiltration was then used successfully and the patient showed remarkable recovery.

Intralipid emulsion treatment as an antidote in lipophilic drug intoxications.

Intravenous lipid emulsion (ILE) is a lifesaving treatment of lipophilic drug intoxications. Not only does ILE have demonstrable efficacy as an antidote to local anesthetic toxicity, it is also effective in lipophilic drug intoxications. Our case series involved 10 patients with ingestion of different types of lipophilic drugs. Intravenous lipid emulsion treatment improved Glasgow Coma Scale or blood pressure and pulse rate or both according to the drug type. Complications were observed in 2 patients (minimal change pancreatitis and probable ILE treatment-related fat infiltration in lungs). In our case series, ILE was used for different lipophilic drug intoxications to improve cardiovascular and neurologic symptoms. According to the results, it was found that ILE treatment is a lifesaving agent in lipophilic drug intoxications and it can be used in unconscious patients who have cardiac and/or neurologic symptoms but no history of a specific drug ingestion.

An assessment of the in vivo effects of intravenous lipid emulsion on blood drug concentration and haemodynamics following oro-gastric amitriptyline overdose.

BACKGROUND: Overdose with lipophilic drugs, such as amitriptyline, may cause cardiotoxicity in overdose. Severe poisoning can be resistant to traditional treatments. Intravenous lipid emulsion (ILE) has been recommended as a novel therapy for the treatment of such overdoses; however, a little is known about the effects of ILE-infusion on drug concentration and haemodynamics in the early/absorptive phase after oral poisoning. METHOD: Thirty minutes after oro-gastric administration of amitriptyline (70 mg/kg), either 20% intravenous lipid emulsion (ILE), 8.4% sodium bicarbonate or Hartmann's solution was infused to anaesthetized and ventilated rodents (n = 10 per group). Heart rate, blood pressure, cutaneous ECG - QRS interval duration (QRS-d), and survival were serially recorded over 120 min. Blood drug concentrations were also collected during this period. Continuous variables were compared using one-way ANOVA. RESULTS: ILE infusion significantly decreased the survival compared to other treatments (10% ILE vs 70% bicarbonate vs 70% Hartmann's solution, p = 0.005). There was a gradual prolongation of QRS-d and fall in blood pressure over time compared to baseline (T0) measurement for both ILE and Hartmann's solution treatments. This was associated with significantly increased blood AMI concentration with ILE treatment at T60, T90 and T120 min to the other treatments (p < 0.02). CONCLUSION: Administration of ILE early after oral amitriptyline overdose resulted in worse survival and no improvement in haemodynamics. In addition, blood amitriptyline concentrations were higher in the ILE-treated group. This suggests that either drug absorption from the gastrointestinal-tract was facilitated or drug redistribution was retarded when ILE was given early after oral poisoning.

Adverse pulmonary vascular effects of high dose tricyclic antidepressants: acute and chronic animal studies.

Overdose of tricyclic antidepressants, which inhibit cellular serotonin (5-HT) uptake, sometimes causes acute respiratory syndrome-like symptoms. Their acute and chronic cardiopulmonary actions, which might be implicated, utilising both in vivo and ex vivo animal studies, were investigated in this study. Acute amitriptyline (AMI), iprindole and imipramine caused dose-dependent prolonged rises in pulmonary artery pressure and oedema in anaesthetised cats in vivo. Acute AMI, in isolated ex vivo blood-perfused rat lungs, also caused dose-dependent sustained vasoconstriction, which could be attenuated with either calcium channel inhibition or a nitric oxide donor. It was demonstrated that the pressor effects of AMI were not due to release of histamine, serotonin, noradrenaline, or the activities of cycloxygenase or lipoxygenase. After AMI, hypoxic pulmonary vasoconstriction and the pressor actions of 5-HT and noradrenaline were diminished, possibly due to uptake inhibition. Activities of the endothelial-based enzymes, nitric oxide synthase and endothelin-converting enzyme, were undiminished. Large acute doses of AMI caused oedema with rupture of capillaries and alveolar epithelium. Chronic iprindole raised pulmonary artery pressure and right ventricle (RV)/left ventricle (LV) + septal (S) weight. Chronic AMI led to attenuation of the pressor action of 5-HT, especially when associated with chronic hypoxic-induced pulmonary hypertension. RV/LV+S weight increased, attributable to LV decline. The acute and chronic effects observed might have relevance to clinical overdose, while the attenuation of acute effects offers possible therapeutic options.

Acute iron poisoning.

Accidental iron ingestion is not uncommon in children and has become a leading cause of unintentional pharmaceutical ingestion fatality. Difficulty in obtaining urgent serum iron levels in majority of hospitals in India, lack of objective indices for starting and stopping the chelation therapy and the cost of chelation therapy, all pose a significant challenge for a clinician in managing an acutely intoxicated patient. This review emphasizes the need for early recognition and correct intervention of a child with acute iron overdose to avoid undue morbidity and mortality.

Intentional overdosage with isoniazid: case report and review of literature.

Isoniazid (INH) is widely used in most prophylactic and therapeutic anti-tuberculosis regimens because of its effectiveness and low cost. Yet, INH poisoning appears to be rare. We report the first case of intentional INH overdosage in Singapore. A 26-year-old Filipino male presented with mental obtundation, recurrent seizures, metabolic acidosis and hepatic dysfunction. He was successfully treated with large doses of pyridoxine (vitamin B6). Recommendations for the management of acute INH toxicity are highlighted.

Acute overdosage with thioridazine: a review of the available clinical exposure.

Two hundred and twenty-three cases of acute overdosage associated with thioridazine were reviewed. The most frequent feature was impairment of consciousness which was linearly dose-related and occasionally resulted in life-threatening complications. Arrhythmia was the most frequently reported serious toxic effect. Patients presenting with anoxia were at risk for arrhythmia, as were patients ingesting a high dose. Arrhythmia may, by decreasing cardiac output, predispose to the occurrence of all other observed complications (ie, pulmonary edema, severe hypotension and renal failure). Therefore, treatment of arrhythmias should be the keystone of management of thioridazine overdosage. Torsade de pointes was reported only once with overdosage. Isolated ventricular arrhythmias (VA) occurred at high doses (median 12 g). At lower doses (median 5 g), VA were frequently associated with conduction disturbances, which were not, as such, statistically predictive of arrhythmias. Since thioridazine in high doses exhibits a beta-adrenoceptor and a verapamil-like calcium channel blocking effect, drugs with these types of properties are contraindicated. VA may be refractory to lidocaine or recur after such therapy. Transient cardiac pacing appears to be the most appropriate management of VA. Although its efficacy is established for the treatment of phenothiazine-induced arrhythmias, its use remains rare (only 3/50 cases).