Comprehensive Safety Information on the use of Ketamine
JBRF has launched a study which will explore the safety and efficacy of ketamine to treat pediatric bipolar disorder in children ages 6-12. One third of the children in the study will be characterized by the Fear of Harm (FOH) phenotype; a subtype of bipolar disorder recently defined from research supported by the Juvenile Bipolar Research Foundation (JBRF).
The following provides:
- a brief description the FOH phenotype and the pilot study that preceded this current study.
- information about the use, efficacy and safety of ketamine in general.
- information specific to the safety measurements incorporated into the current study protocol.
JBRF SUPPORTED RESEARCH
The FOH phenotype describes a population of children who are severely impaired, often refractory to treatment, and currently fall under a bipolar classification. Symptoms experienced by these children include not only those typical of bipolar disorder, but also a broad range of symptoms currently included in classifications considered co-morbid to bipolar disorder as well as some symptoms never previously associated with any psychiatric classification. This new constellation of symptoms allowed investigators to trace the condition to a particular neuropathway that is the most ancient sensory pathway in the brain and is intimately involved in homeostasis. Further exploration of this pathway has led to a neuroanatomical model of the condition as well as a hypothesis of its pathophysiology. From this framework, ketamine was selected as an appropriate agent to target the dysregulation.
A pilot study was conducted within a private practice setting. Intranasal ketamine was administered to 12 subjects, aged 6-30, all of whom screened positive for pediatric-onset bipolar disorder with FOH phenotype. Treatment resulted in a rapid and enduring resolution of a large majority of their most severe behavioral and physiological symptoms. As of January, 2011, continuous treatment of these subjects ranged from 3 months to almost two and a half years. By this writing, another 25 children have enrolled in this naturalistic pilot treatment study and experienced similar positive responses. All subjects continue to receive regular administrations of ketamine.
This current study has been initiated to document these observations through a double-blind placebo-controlled study.
The study has received both Internal Review Board (BioMed IRB) and Food and Drug Administration (FDA) approval. Registration of the study can be found at:
USE, EFFICACY AND SAFETY INFORMATION OF KETAMINE
CHARACTERISTICS and HISTORICAL USE:
Since its creation in 1961 and introduction to clinical practice in 1970, ketamine has garnered a long record of efficacy and safety as a sedation and analgesic agent. It has been used both in combination with other sedation agents and by itself in both clinical and veterinary arenas. Ketamine is a core medicine in the World Health Organization’s “Essential Drugs List” and its ability to provide sedation without the need for intubation has made it a standard technique for the American Red Cross.[i]
When ketamine is administered in doses between 1-3mg/kg IV or 3-4mg/kg IM, it induces a unique dissociative state which disconnects the central nervous system (CNS) from external stimuli (i.e. pain, sight, sound) and accomplishes potent analgesia, amnesia and sedation.[ii] However, this state is pharmacologically and clinically distinct from general anesthetics in three important ways: 1) it does not impair respiration, airway reflexes or cardiovascular stability, 2) it does not exert its effect along a dose-response continuum; that is, once a dissociative state is reached, that state does not deepen nor will it deepen with additional drug administration, and 3) it does not exert its effects through global CNS depression, instead it dissociates the CNS through its effects on the thalamoneocortical and limbic systems.[iii] Due to the first two points, unlike anesthetic agents, once a dissociative-sedation state is produced by ketamine, increased administration is not accompanied by an increased probability of ventilatory depression[iv] and therefore intubation is rarely needed. Within the range of standard, clinically administered dissociative sedation doses and using standard administration methods, there are neither clinically important changes in airway integrity and respiration[v] nor clinically important incidence or severity of adverse events.[vi] Only high and/or rapid IV administration predicted an increased risk of agitation.[vii],[vii].
Ketamine use in the United States far less frequent than elsewhere. This is likely due, in large part, to wariness over emergence reactions that sometimes follow the use of this phencyclidine derivative.[ix],[x] The experience has limited use of the drug despite the fact that in all but a few cases[xi],[xii],[xiii] out of the many hundreds of thousands[xiv],[xv] in which use has been reported, the effects have been transient and typically resolve within 30-120 minutes.[xvi],[xvii] Ketamine is the number one agent used to sedate children in the emergency room and is frequently used in dental offices.
In addition to its widespread dissociative use, ketamine has a long clinical history of off-label use as an analgesic. It has been used as a treatment for a wide spectrum of pain syndromes, including neuropathic pain, phantom limb pain, postoperative pain, acute traumatic pain, complex regional pain syndrome and breakthrough and regional chronic pain.[xviii],[xix],[xx],[xxi] In some neurological ICUs, ketamine has been used in cases of prolonged status epilepticus in order to protect neurons from glutamatergic damage.[xxii] Finally, ketamine has been known to have bronchodilatory effects and to be used in the treatment of bronchospasm.[xxiii]
The several documented cases of unintentional ketamine overdose, up to 100 times that required, have been followed by prolonged, but complete, recovery.[xxiv] Median lethal dose of intraperitoneal ketamine hydrochloride is 224 mg/kg in rats and 229 mg/kg in mice.[xxv] In guinea pigs, the LD50 of ketamine hydrochloride ranges from 351 to 373 mg/kg when given by intramuscular injection with 10 mg/kg of xylazine (a short-acting sedative).[xxvi]
ADVERSE EVENTS and SIDE EFFECTS ASSOCIATED WITH THE MEDICAL USE OF KETAMINE:
Emergence from ketamine sedation causes the well known psychotomimetic effects associated with the drug. The percentage of children who experience emergence phenomena or recovery agitation is much smaller than that of adults and almost no children express or exhibit distress from them when emerging from ketamine sedation.[xxvii],[xxviii] While reports of recovery agitation are not infrequent (app. 20%), the event was only judged moderate to severe in 1.6% of the cases.[xxix] In one trial in which the reaction was quantified, the investigators found that the median agitation score was 5 out of 100.[xxx] It is worth noting here that these observations pertain to the use of ketamine to achieve complete, rather than partial dissociation as the case will be for our study.
Since ketamine does not depress the respiratory system it does not require respiratory support. While some adverse respiratory events have been documented, the incidence and nature of these events are not of clinical importance. A 2009 meta-analysis of 8,282 pediatric ketamine sedation cases found incidence of airway malalignment and respiratory depression together was 2.8% (234 cases), apnea was 0.8% (63 cases) and laryngospasm was 0.3% (22 cases).[xxxi] The commensurate corrective action required for these kinds of advents was recorded in an earlier study of 1,022 cases. In that study, for the 7 cases of airway complications, repositioning of the head alleviated partial obstruction and no assisted ventilation was performed. In the seven cases of transient laryngospasm, apnea or respiratory depression, none of the cases required endotracheal intubation and all cases were completed with uneventful recovery.[xxxii] We are not aware of any instances of adverse respiratory events in children in which an intranasal administration of ketamine is used.[xxxiii],[xxxiv],[xxxv]
The presence of lower urinary tract symptoms (LUTS) associated with ketamine use has garnered recent attention and concern in the urological community. Our review of the literature indicates that LUTS follows extremely high doses of ketamine (between hundreds and thousands of times higher than the doses in the study), typically over a long period of time and during which medical attention is not sought despite the presence of symptoms.
Other side effects of ketamine include nausea, vomiting, fatigue and headache.
Despite the phencyclidine characteristic of ketamine, ketamine does not create a physical addiction.[xxxvi]
KETAMINE AND NEUROTOXICITY:
Studies have documented that ketamine has a neurotoxic impact on the fetal or neonatal rat brain. However, Scallet et al. (2004) extended the findings of these toxicological studies by comparing the ketamine serum levels associated with neurotoxicity in the rats to the ketamine serum levels typical of ketamine use in humans. Their study determined that ketamine serum levels at which neurodegeneration occurs in the neonatal rat is 7-fold greater than the mean ketamine serum level resultant from dissociation in humans. When ketamine was administered to PND 7 rats, at a dose which generated a similar ketamine serum levels to human dissociation, no neurodegeneration occurred.[xxxvii] Since the ketamine dose used in our study is commensurate with an analgesic, rather than dissociative use, it is safe to say that there is a wide margin of safety to the risk of neurodegeneration.
Further, a neurotoxicity study conducted by Wang et al. in 2005 demonstrated that, while widespread and dose dependent apoptotic neurodegeneration occurred in in vivo PND 1 rat forebrains when treated with increasing amount of N-methyl-d-aspartate (NMDA) antagonists such as ketamine (up to 20µM), that this effect is restricted to the period of synaptogenesis.[xxxviii]
THE USE OF KETAMINE FOR MOOD DISORDER:
Concurrent to the pilot study described above, several small, controlled studies have illustrated the considerable potential of ketamine to provide fast-acting and sustained relief in refractory depression, refractory bipolar disorder and in patients with severe suicidal ideation. Due to their impressive findings, these studies have recently come into the popular media. The landmark clinical study, by Berman et al. (2000) found that in a randomized, double-blind study, 7 subjects with major depressive disorder experienced significant improvement in depressive symptoms within 72 hrs. post-treatment with 0.5 mg/kg IV ketamine.[xxxix] In 2 randomized, placebo-controlled, double-blind crossover studies by Zarate el al., one in 2006 in which 18 patients with refractory major depressive disorder were studied and the other in 2010, in which 18 patients with refractory bipolar depression were studied, investigators found that 71% of the patients in each study achieved significant, rapid and enduring clinical improvement after intravenous infusion of 0.5 mg/kg ketamine.[xl],[xli] Similar findings have now been replicated by several groups.[xlii],[xliii],[xliv],[xlv]
There are many characteristics that associate children with the FOH phenotype to the treatment refractory adults of the above studies –but they will not be addressed here. What is relevant is that, like the adults in the above studies, children with the FOH phenotype have responded to ketamine in an equally positive manner. Administration of the intranasal formulation is easy to manage and its effects typically endure for 3-5 days.
INFORMATION RELEVANT TO THE IMPLEMENTATION AND SAFETY OF THIS STUDY
Except for contraindications directly related to surgical considerations, exclusion criteria for our study follows the Clinical Practice Guideline for Emergency Department Ketamine Dissociative Sedation: 2011 Update[xlvi] by Green et al. While these contraindications are advised for the dissociative use of drug, rather than the sub-dissociative use called for in our study, adoption of them will ensure an extra margin of safety. Screening prior to enrollment will disqualify children with exclusionary criteria.
Ketamine will be administered to the child in his/her home by a PA, NP or APRN specifically trained for this study. He or she will arrive an hour before the administration to confirm that the child is healthy enough to receive the dose and to irrigate the child’s nasal passages. The latter is to maximize an accurate delivery of drug/placebo. After administration, the PA, NP or APRN will remain in the child’s home for another 2 hours to monitor for adverse events. Two hours is the well established window in which all the side effects of ketamine resolve.
For this study, children have been divided into two groups depending upon weight. Group A, with minimum-maximum weight of 20 kg-40 kg will receive a fixed initial dose of 10 mg (0.25-0.5mg/kg). Group B with minimum – maximum weight of 40.01kg-100kg will get a fixed initial dose of 20 mg (0.20-0.5mg/kg). Over the following 3 administrations, the dose will increase by 10mg unless a therapeutic response has been achieved in which case the dose level will hold. This means that the maximum dose for the smaller children will be 2mg/kg. The maximum dose for the larger children will be 1.25mg/kg. These doses are significantly lower than a dissociative dose and are more similar to an analgesic dose. While psychotomimetic effects may occur at these lower doses, there is a wide berth to dissociative sedation levels.
During the two hours post-dose that the PA/NP/APRN remains with the child, she/he will use the Clinician-Administered Dissociative States Scale (CADSS) to measure the psychotomimetic emergence reactions which can follow the use of ketamine. Additionally, she/he will administer the Systematic Assessment for Treatment Emergent Effects (SAFTEE) and the Brief Psychiatric Rating Scale (BPRS). Finally, vital signs will be measured prior to, and at increasing intervals for the 60 minutes after the dose.
As for the rare respiratory distress caused by ketamine, our review of the literature finds that the overwhelming recommendation is for the presence of a person dedicated to the observation of the patient who is skilled in advanced airway management and has access to appropriate equipment such as a bag valve mask. The current study wholly adopts this recommendation.
As for reports of LUTS associated with ketamine use, the medical screening and urinalysis prior to participation (as indicated in the Medical Clearance) will insure that the child has no preexisting bladder condition. Further, we will inquire about changes in urination pattern during the study, at three month follow up, and advise parents to seek treatment at any time that they notice such a change. No child who is currently treated with ketamine has experienced any LUTS.
Other less serious adverse effects such as nausea or vomiting, while unpleasant, are not of clinical concern. Side effects specific to the intranasal administration also include a bitter taste (which is mitigated by sucking on hard candy during drug administration), and a sensation of burning in the pharynx.75 In the pilot study, we have also reported on a chilling sensation prior to therapeutic response.
 Our research indicates that two thirds of the children who currently have a community diagnosis of bipolar disorder fall within an FOH spectrum: 1/3 high and 1/3 low. We are very concerned with the looming re-allocation of some of these children to the proposed Temper Dysregulation Disorder (TDD) classification pursuant to its codification.
 Published articles are:
A strategy for identifying phenotypic subtypes- Concordance of symptom dimensions between sibling pairs who met screening criteria for a genetic linkage study of childhood-onset bipolar disorder using the Child Bipolar Questionnaire
[i] Green SM, Rothrock SG, Lynch EL, et al. Intramuscular Ketamine for Pediatric Sedation in the Emergency Department: Safety Profile in 1,022 Cases. Annals of Emergency Medicine. 1998;31(6):688-697.
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[iv] Green SM, Roback MG, Kennedy RM, Krauss B. Clinical Practice Guideline for Emergency Department Ketamine Dissociative Sedation: 2011 Update. Ann Emerg Med. Jan 20 2011.
[v] Green SM, Roback MG, Krauss B, et al. Predictors of airway and respiratory adverse events with ketamine sedation in the emergency department: an individual-patient data meta-analysis of 8,282 children. Ann Emerg Med. Aug 2009;54(2):158-168 e151-154.
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[xxx] Sherwin TS, Green SM, Khan A, Chapman DS, Dannenberg B. Does adjunctive midazolam reduce recovery agitation after ketamine sedation for pediatric procedures? A randomized, double-blind, placebo-controlled trial. Annals of Emergency Medicine. 2000;35(3):229-238.
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[xxxii] Green SM, Rothrock SG, Lynch EL, et al. Intramuscular Ketamine for Pediatric Sedation in the Emergency Department: Safety Profile in 1,022 Cases. Annals of Emergency Medicine. 1998;31(6):688-697.
[xxxiii] Abrams R, Morrison JE, Villasenor A, Hencmann D, Da Fonseca M, Mueller W. Safety and effectiveness of intranasal administration of sedative medications (ketamine, midazolam, or sufentanil) for urgent brief pediatric dental procedures. Ansethsia Progress. 1993;40(3):4.
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[xl] Zarate CA, Jr., Singh JB, Carlson PJ, et al. A randomized trial of an N-methyl-D-aspartate antagonist in treatment-resistant major depression. Arch Gen Psychiatry. Aug 2006;63(8):856-864.
[xli] Diazgranados N, Ibrahim L, Brutsche NE, et al. A randomized add-on trial of an N-methyl-D-aspartate antagonist in treatment-resistant bipolar depression. Arch Gen Psychiatry. Aug 2010;67(8):793-802.
[xlii] Krystal JH. Ketamine and the potential role for rapid-acting antidepressant medications. Swiss Med Wkly. Apr 21 2007;137(15-16):215-216.
[xliii] Price RB, Nock MK, Charney DS, Mathew SJ. Effects of intravenous ketamine on explicit and implicit measures of suicidality in treatment-resistant depression. Biol Psychiatry. Sep 1 2009;66(5):522-526.
[xliv] Phelps LE, Brutsche N, Moral JR, Luckenbaugh DA, Manji HK, Zarate CA, Jr. Family history of alcohol dependence and initial antidepressant response to an N-methyl-D-aspartate antagonist. Biol Psychiatry. Jan 15 2009;65(2):181-184.
[xlv] Liebrenz M, Borgeat A, Leisinger R, Stohler R. Intravenous ketamine therapy in a patient with a treatment-resistant major depression. Swiss Med Wkly. Apr 21 2007;137(15-16):234-236.
[xlvi] Green SM, Roback MG, Kennedy RM, Krauss B. Clinical Practice Guideline for Emergency Department Ketamine Dissociative Sedation: 2011 Update. Ann Emerg Med. Jan 20 2011.