Ketamine

Today's med: Ketamine (KEET a meen) (brand name: Ketalar)

Drug Class: General Anesthetic, NMDA receptor antagonist. 
Schedule III Controlled substance

Other Drugs in this class: Propofol,Nitrous oxide, Etomidate, Memantine,Isoflurane, 
Amantadine, Sevoflurane,Riluzole, Desflurane, Enflurane, Ketamine hydrochloride

Indications: Induction and maintenance of general anesthesia

Action: Produces a cataleptic-like state in which the patient is dissociated from the surrounding environment by direct action on the cortex and limbic system. Ketamine is a noncompetitive NMDA receptor antagonist that blocks glutamate. Low (subanesthetic) doses produce analgesia, and modulate central sensitization, hyperalgesia and opioid tolerance. Reduces polysynaptic spinal reflexes.

Onset of Action

I.V.: Anesthetic effect: 30 seconds

I.M.: Anesthetic effect: 3-4 minutes

Duration of Action

Anesthetic effect: I.V.: 5-10 minutes; I.M.: 12-25 minutes

Half-Life Elimination

Alpha: 10-15 minutes; Beta: 2.5 hours

Lab Interference: May interfere with urine detection of PCP (false-positive).

Contraindications: Hypersensitivity to ketamine or any component of the formulation; conditions in which an increase in blood pressure would be hazardous

Adverse Effects: Frequency not always defined.

Cardiovascular: Arrhythmia, bradycardia/tachycardia, hyper-/hypotension

Central nervous system: Intracranial pressure increased

Dermatologic: Erythema (transient), morbilliform rash (transient)

Gastrointestinal: Anorexia, nausea, salivation increased, vomiting

Local: Pain at the injection site, exanthema at the injection site

Neuromuscular & skeletal: Skeletal muscle tone enhanced (tonic-clonic movements)

Ocular: Diplopia, intraocular pressure increased, nystagmus

Respiratory: Airway obstruction, apnea, bronchial secretions increased, respiratory depression, laryngospasm

Miscellaneous: Anaphylaxis, dependence with prolonged use, emergence reactions (~12%; includes confusion, delirium, dreamlike state, excitement, hallucinations, irrational behavior, vivid imagery)

Concerns related to adverse effects:

• CNS depression: May cause CNS depression, which may impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving). When used for outpatient surgery, the patient should be accompanied by a responsible adult.

• Dependence: May cause dependence (withdrawal symptoms on discontinuation) and tolerance with prolonged use.

• Emergence reactions: Postanesthetic emergence reactions which can manifest as vivid dreams, hallucinations, and/or frank delirium occur; these reactions are less common in patients <15 years of age and >65 years and when given intramuscularly. Emergence reactions, confusion, or irrational behavior may occur up to 24 hours postoperatively and may be reduced by pretreatment with a benzodiazepine and the use of ketamine at the lower end of the dosing range.

• Respiratory depression: Rapid I.V. administration or overdose may cause respiratory depression or apnea. Resuscitative equipment should be available during use.

Standard Dosing:  May be used in combination with anticholinergic agents to decrease hypersalivation.

Children: Note: Titrate dose for desired effect.

Sedation (unlabeled use): Oral (unlabeled route): 5-8 mg/kg for 1 dose (mixed in 0.2-0.3 mL/kg of cola or other beverage) given 30 minutes before the procedure (Sacchetti, 1994; Rosenberg, 1991)

Sedation/analgesia (unlabeled use):

I.M.: 2-5 mg/kg/dose (Green, 2011; Krause, 2000; McGlone, 2004; White, 1982)

I.V.: 0.5-1 mg/kg/dose (Sacchetti, 1994; Tobias, 1990)

Continuous I.V. infusion: 5-20 mcg/kg/minute (White, 1982; Tobias, 1990)

Children ≥16 years and Adults: Note: Titrate dose for desired effect.

Sedation/analgesia (unlabeled use):

I.M.: 2-4 mg/kg (White, 1982)

I.V.: 0.2-0.75 mg/kg (White, 1982)

Continuous I.V. infusion: 2-7 mcg/kg/minute (Hocking, 2003; Remérand, 2009; Zakine, 2008)

Critically-ill patients: Loading dose: 0.1-0.5 mg/kg; followed by 0.83-6.7 mcg/kg/minute (equivalent to 0.05-0.4 mg/kg/hour) (Barr, 2013)

Induction of anesthesia (unlabeled dosing):

I.M.: 4-10 mg/kg (Green, 1990; Miller, 2010; White, 1982)

I.V.: 0.5-2 mg/kg (Miller, 2010; White, 1982)

Maintenance of anesthesia: May administer supplemental doses of one-half to the full induction dose or a continuous infusion of 0.1-0.5 mg/minute (per manufacturer). Note: To maintain an adequate concentration of ketamine for maintenance of anesthesia, 1-2 mg/minute has been recommended (White, 1982); doses in the range of 15-90 mcg/kg/minute (~1-6 mg/minute in a 70-kg patient) have also been suggested (Miller, 2010). Concurrent use of nitrous oxide reduces ketamine requirements.

Drug interactions: http://www.drugs.com/drug-interactions/ketamine.html

• 9 major drug interactions (35 brand and generic names)
• 543 moderate drug interactions (3494 brand and generic names)
• 2 minor drug interactions (5 brand and generic names)

Show all medications in the database that may interact with ketamine.

Major interactions with: acetaminophen and aspirin!

CYP2B6 Inhibitors (Moderate): May decrease the metabolism of CYP2B6 Substrates. Monitor therapy

CYP2B6 Inhibitors (Strong): May decrease the metabolism of CYP2B6 Substrates. Consider therapy modification

CYP2C9 Inducers (Strong): May increase the metabolism of CYP2C9 Substrates. Management: Consider an alternative for one of the interacting drugs. Some combinations may be specifically contraindicated. Consult appropriate manufacturer labeling. Consider therapy modification

CYP2C9 Inhibitors (Moderate): May decrease the metabolism of CYP2C9 Substrates. Monitor therapy

CYP2C9 Inhibitors (Strong): May decrease the metabolism of CYP2C9 Substrates. Consider therapy modification

CYP3A4 Inhibitors (Moderate): May decrease the metabolism of CYP3A4 Substrates. Monitor therapy

CYP3A4 Inhibitors (Strong): May decrease the metabolism of CYP3A4 Substrates. Consider therapy modification

From: http://www.cesar.umd.edu/cesar/drugs/ketamine.asp
The effects of ketamine are considered dose dependent. That is, lower doses of the drug produce varying results when compared to higher doses. A dose of 1.0 to 2.0 mg per kilogram of body weight produces an intense experience lasting about one hour. The effects include a sense of floating and dissociation, stimulation, and hallucinations. Larger doses of ketamine may produce what users refer to as a “K-hole.” A K-hole is generally reached when the user is on the brink of being fully sedated and is likened to an out-of-body or near-death experience. High doses of ketamine may result in severe respiratory depression, muscle twitches, dizziness, slurred speech, nausea, and vomiting.16 One of the most dangerous effects of ketamine is the helpless and/or confused state the user may be put into after use of the drug. This causes the user to have difficulty with balance, combined with numbness, muscle weakness, and impaired vision. The combined effects can leave the user vulnerable to particular forms of crime,17 especially "date rape". Other physical side effects for all users can include:

• Flashbacks
• Amnesia
• Impaired motor functioning
• Delirium (hallucinations or disorientation)
• Dramatic increase in heart rate (tachycardia)
• Loss of touch with reality (derealization)
• Loss of coordination
• Sense of invulnerability
• Muscle rigidity
• Aggressive/Violent behavior
• Death from overdose - in severe instances

Terminology

Slang Terms for Ketamine:

Special K, Vitamin K, K, Super K, Ketaset, Jet, Super Acid, Green, Purple, Mauve, Special LA Coke