Consumer medicine information

Ketamine APOTEX

Ketamine

BRAND INFORMATION

Brand name

Ketamine APOTEX

Active ingredient

Ketamine

Schedule

S8

 

Consumer medicine information (CMI) leaflet

Please read this leaflet carefully before you start using Ketamine APOTEX.

What is in this leaflet

This leaflet answers some common questions about this medicine. It does not contain all the available information. It does not take the place of talking to your doctor or pharmacist.

All medicines have risks and benefits. Your doctor has weighed the risks of you using this medicine against the benefits they expect it will have for you.

If you have any concerns about taking this medicine, ask your doctor or pharmacist.

Keep this leaflet with you. You may need to read it again.

What this medicine is used for

The name of your medicine is Ketamine Apotex solution for injection. It contains the active ingredient ketamine hydrochloride.

Ketamine is used to make the body insensitive to surgical treatment. It may be used in combination with other medicines to induce anaesthesia.

Ketamine belongs to a group of medicines called anaesthetics.

It works by stopping the brain from interpreting messages of pain.

Ask your doctor if you have any questions about why this medicine has been prescribed for you. Your doctor may have prescribed this medicine for another reason.

This medicine is addictive.

Individuals with a history of drug abuse or dependence may develop ketamine dependence and tolerance; however, addiction is unlikely to occur when ketamine is used as prescribed for anaesthesia.

This medicine is available only with a doctor's prescription.

Before you are given this medicine

When you must not be given this medicine

You must not be given this medicine if you have an allergy to:

  • ketamine
  • any of the ingredients listed at the end of the leaflet

Some of the symptoms of an allergic reaction may include:

  • cough, shortness of breath
  • wheezing or difficulty breathing
  • swelling of the face, lips, tongue, throat or other parts of the body
  • rash, itching or hives on the skin

You must not be given this medicine if you have or have had any of the following medical conditions:

  • poorly controlled blood pressure
  • severe heart disease
  • heart failure
  • a recent history of stroke
  • recent heart attack
  • brain haemorrhage
  • brain trauma

You must not be given this medicine after the expiry date printed on the pack or if the packaging is torn or shows signs of tampering.

If you are not sure whether you should be given this medicine, talk to your doctor.

Before you are given it

Tell your doctor if you have allergies to any other medicines, foods, preservatives or dyes.

Tell your doctor if you have or have had any of the following medical conditions:

  • heart problems, including heart attack
  • dehydration
  • high blood pressure
  • breathing problems, including chest infections and asthma
  • alcohol intoxication or history of alcohol abuse
  • drug abuse or drug dependence
  • cerebral or head problems including injury, lesions or elevated cerebrospinal fluid pressure
  • psychiatric disorders (e.g. schizophrenia, acute psychosis)
  • overactive thyroid
  • glaucoma
  • kidney or liver disease (e.g. porphyria or cirrhosis)
  • seizures (fits or convulsions)

Tell your doctor if you are currently pregnant, plan to become pregnant, or are breastfeeding. Your doctor can discuss with you the risks and benefits involved.

If you have not told your doctor about any of the above, tell them before you are given this medicine.

Taking other medicines

Tell your doctor or pharmacist if you are taking any other medicines, including any that you get without a prescription from your pharmacy, supermarket or health food shop.

Some medicines and ketamine may interfere with each other. These include:

  • general anaesthetics (used to put you to sleep during an operation) and hypnotics (e.g. thiopental)
  • barbiturates (used to treat epilepsy)
  • narcotic analgesics (used to relieve pain)
  • sedatives or anxiolytic drugs (medicine used to help relieve anxiety)
  • alcohol
  • benzodiazepines (used as sedatives or to treat anxiety)
  • ergometrine (used sometimes after giving birth)
  • thyroxine or thyroid hormones
  • theophylline (used for breathing problems or asthma)
  • antihypertensives (used to help lower high blood pressure)
  • muscle relaxants used in anaesthesia (atracurium and tubocurarine)
  • antidiuretic hormones, such as vasopressin
  • medicines affecting your heart or circulation system, or that increase your blood pressure

These medicines may be affected by ketamine or may affect how well it works. You may need different amounts of your medicines, or you may need to take different medicines.

Your doctor and pharmacist have more information on medicines to be careful with or avoid while taking this medicine.

Other medicines not listed above may also interact with ketamine.

How this medicine is given

How much is given

Your doctor will decide what dose you will receive. This depends on your condition and other factors, such as your age, weight and other medicines that are being given.

How it is given

Ketamine is given as an injection into a muscle, or as a slow injection into a vein. It must only be given by a nurse or doctor.

If you receive too much (overdose)

As ketamine is given to you in a hospital under the supervision of your doctor, it is very unlikely that you will receive an overdose. You will be closely monitored in hospital during the early post-operative period so that any unwanted side effects can be treated. However, if you experience severe side effects tell your doctor immediately.

Symptoms of an overdose may include the side effects listed below in the 'Side Effects' section but are usually of a more severe nature.

In the case of an overdose, immediately telephone your doctor or the Poisons Information Centre (telephone 13 11 26) for advice. Alternatively, go to the Accident and Emergency department at your nearest hospital.

Do this even if there are no signs of discomfort or poisoning. You may need urgent medical attention.

While you are being given this medicine

Things you must do

If you are about to be started on any new medicine, remind your doctor and pharmacist that you are being given this medicine.

Tell any other doctors, dentists, and pharmacists who treat you that you are being given this medicine.

If you are going to have surgery, tell the surgeon or anaesthetist that you are being given this medicine. It may affect other medicines used during surgery.

If you become pregnant or start to breastfeed while taking this medicine, tell your doctor immediately.

Keep all your doctor's appointments so that your progress can be checked. Your doctor may do some tests from time to time to make sure the medicine is working and to prevent unwanted side effects.

Things to be careful of

Be careful driving, operating machinery or engaging in hazardous activities for at least 24 hours after receiving ketamine.

When ketamine is used on an outpatient basis, you should not be released from medical care until you have completely recovered from the anaesthesia, and then you should be accompanied by a responsible adult.

Do not drink alcohol for 24 hours after you have been given this medicine.

Side effects

Tell your doctor or nurse as soon as possible if you do not feel well when you are given ketamine.

Ketamine may have unwanted side effects in a few people. All medicines can have side effects. Sometimes they are serious, most of the time they are not. You may need medical attention if you get some of the side effects.

Do not be alarmed by the following lists of side effects. You may not experience any of them.

Ask your doctor or pharmacist to answer any questions you may have.

Tell your doctor, nurse or pharmacist if you notice any of the following:

  • nausea, vomiting
  • increased saliva
  • pain at the injection site

The above list includes the more common side effects of your medicine.

Tell your doctor or nurse as soon as possible if you notice any of the following:

  • rash
  • double vision or abnormal eye movements

These may be serious side effects and you may need medical attention.

If any of the following happen, tell your doctor or nurse immediately or go to the Accident and Emergency department at your nearest hospital.

  • signs of an allergic reaction, such as cough, shortness of breath, wheezing or difficulty breathing; swelling of the face, lips, tongue, throat or other parts of the body; rash, itching or hives on the skin
  • confusion, excitation, irrational behaviour
  • hallucinations, vivid imagery, dream-like states, nightmares
  • movements resembling seizures
  • breathing difficulties
  • elevated blood pressure, rapid pulse rate, heart palpitations

The above list includes very serious side effects. You may need urgent medical attention or hospitalisation.

Tell your doctor or pharmacist if you notice anything that is making you feel unwell.

Other side effects not listed above may occur in some patients.

Storage and disposal

Storage

Ketamine will be stored in the pharmacy or on the ward. The injection is kept in a cool dry place, protected from light where the temperature stays below 30°C.

Disposal

Ketamine is used for one dose in one patient only. Any remaining contents should be discarded.

Product description

What Ketamine APOTEX solution for injection looks like

200mg/2mL solution for injection, 2mL ampoule (type I clear glass):

A clear and colourless to slightly yellow solution, essentially free from visible particulate matter. AUST R 219040.

Available in packages of 5 ampoules.

Ingredients

Each ampoule contains 200mg of ketamine hydrochloride as the active ingredient.

It also contains the following:

  • water for injections

This medicine does not contain any gluten, lactose, sucrose, tartrazine and is free of other azo dyes.

Sponsor

Apotex Pty Ltd
16 Giffnock Avenue
Macquarie Park NSW 2113
Australia

APO and APOTEX are registered trademarks of Apotex Inc.

This leaflet was last updated in September 2019.

Published by MIMS November 2019

BRAND INFORMATION

Brand name

Ketamine APOTEX

Active ingredient

Ketamine

Schedule

S8

 

1 Name of Medicine

Ketamine hydrochloride.

2 Qualitative and Quantitative Composition

Ketamine solution for injection contains ketamine 200 mg in 2 mL.
Ketamine APOTEX solution for injection is formulated as an acid (pH 3.5 to 5.5) solution for intravenous or intramuscular injection in concentrations containing the equivalent of 100 mg ketamine base per millilitre.

Excipients with known effect.

None stated.
For the full list of excipients see Section 6.1 List of Excipients.

3 Pharmaceutical Form

Solution for injection.
The solution is clear and colourless to slightly yellow, essentially free from visible particulate matter.

4 Clinical Particulars

4.1 Therapeutic Indications

Ketamine is recommended:
as the sole anaesthetic agent for diagnostic and surgical procedures that do not require skeletal muscle relaxation. Ketamine is best suited for short procedures and it can be used with additional doses, for longer procedures;
for the induction of anaesthesia prior to the administration of other general anaesthetic agents;
to supplement low-potency agents, such as nitrous oxide.

4.2 Dose and Method of Administration

Ketamine injection is intended for intravenous or intramuscular injection.
Ketamine injection is for single use in one patient only. Discard any residue.

Pre-operative preparation.

While vomiting has been reported following ketamine administration, airway protection is usually afforded because of active laryngeal-pharyngeal reflexes. However, because these reflexes may also be diminished by supplementary anaesthetics or muscle relaxants, the possibility of aspiration must be considered. Ketamine is recommended for use in the patient whose stomach is not empty only when, in the judgment of the medical practitioner, the benefits of the drug outweigh the possible risks.
Atropine, hyoscine or other 'drying' agents should be given at an appropriate interval prior to induction.

Dosage.

As with other general anaesthetic agents, the individual response to ketamine is somewhat varied depending on the dose, route of administration and age of patient, so that the dosage recommended cannot be absolutely determined in a fixed manner. The drug should be titrated against the patient's requirements.

Onset and duration.

Because of rapid induction following the initial intravenous injection, the patient should be in a supported position during administration. The onset of action of ketamine is rapid; an intravenous dose of 2 mg/kg of body weight usually produces surgical anaesthesia within 30 seconds after injection, with the anaesthetic effect usually lasting 5 to 10 minutes. If a longer effect is desired, additional increments can be administered intravenously or intramuscularly to maintain anaesthesia without producing significant cumulative effect.
From experience, intramuscular doses (primarily in children, in a range of 9 to 13 mg/kg) usually produce surgical anaesthesia within 3 to 4 minutes following administration, with the anaesthetic effect usually lasting 12 to 25 minutes.

Induction.

Intravenous route. The initial dose of ketamine administered intravenously may range from 1 mg/kg to 4.5 mg/kg. The average amount required to produce 5 to 10 minutes of surgical anaesthesia has been 2 mg/kg.

Note.

The 100 mg/mL concentration of ketamine should not be injected intravenously without appropriate dilution. It is recommended the drug be diluted with an equal volume of either sterile water for injection, normal saline or 5% glucose in water. To reduce microbiological hazard, use as soon as practicable after dilution. If storage is necessary, hold at 2-8°C for not more than 24 hours.

Rate of administration.

It is recommended that ketamine be administered slowly (over a period of 60 seconds). More rapid administration may result in respiratory depression and enhanced pressor response.
Intramuscular route. The initial dose of ketamine administered intramuscularly ranges from 6.5 to 13 mg/kg. A dose of 10 mg/kg will usually produce 12 to 25 minutes of surgical anaesthesia. If the ketamine dose is augmented with diazepam, the two drugs must be given separately. Do not mix ketamine and diazepam in the same syringe or infusion flask.

Dosage in hepatic insufficiency.

Dose reductions should be considered in patients with cirrhosis or other types of liver impairment (see Section 4.4 Special Warnings and Precautions for Use).

Maintenance of anaesthesia.

Increments of one half to the full induction dose may be repeated, as needed, for maintenance of anaesthesia. However, it should be noted that involuntary and tonic-clonic movements of extremities might occur during the course of anaesthesia. These movements do not imply a level of attenuated anaesthesia and are not indicative of the need for additional doses of the anaesthetic. It should be recognised that the greater the total dose of ketamine administered, the longer will be the time to complete recovery.
This product is for one dose in one patient only. Discard any remaining contents.

4.3 Contraindications

Ketamine is contraindicated in patients with any condition in which a significant elevation of blood pressure would be hazardous such as: severe cardiovascular disease, heart failure, severe or poorly controlled hypertension, recent myocardial infarction, history of stroke, cerebral trauma, intracerebral mass or haemorrhage. Ketamine is also contraindicated in those who have shown hypersensitivity to the drug or its components.

4.4 Special Warnings and Precautions for Use

Ketamine should be used by or under the direction of medical practitioners experienced in administering general anaesthetics and in maintenance of an airway and in the control of respiratory support.
Barbiturates and ketamine, being chemically incompatible because of precipitate formation, should not be injected from the same syringe.
Prolonged recovery time may occur if barbiturates and/or narcotics are used concurrently with ketamine.
Post-operative confusional states may occur during the recovery period (see Section 4.4 Special Warnings and Precautions for Use, Emergence reaction).
Because pharyngeal and laryngeal reflexes are usually active, ketamine should not be used alone in surgery or diagnostic procedures of the pharynx, larynx or bronchial tree. Mechanical stimulation of the pharynx should be avoided, whenever possible, if ketamine is used alone. Muscle relaxants with proper attention to respiration, may be required in both of these instances.
Resuscitative equipment should be ready for use.
The intravenous dose should be administered over a period of 60 seconds. More rapid administration may result in respiratory depression or apnoea and enhanced pressor response.
In surgical procedures involving visceral pain pathways, ketamine should be supplemented with an agent, which obtunds visceral pain.
Use with caution in the chronic alcoholic and the acutely alcohol-intoxicated patient.
An increase in cerebrospinal fluid pressure has been reported following administration of ketamine. Use with extreme caution in patients with pre-anaesthetic elevated cerebrospinal fluid pressure.
Use with caution in patients with increased intraocular pressure (e.g. glaucoma) because the pressure may increase significantly after a single dose of ketamine.
Use with caution in patients with neurotic traits or psychiatric illness (e.g. schizophrenia and acute psychosis).
Use with caution in patients with acute intermittent porphyria.
Use with caution in patients with seizures.
Use with caution in patients with hyperthyroidism or patients receiving thyroid replacement (increased risk of hypertension and tachycardia).
Use with caution in patients with pulmonary or upper respiratory infection (ketamine sensitises the gag reflex, potentially causing laryngospasm).
Use with caution in patients with intracranial mass lesions, a presence of head injury, globe injuries, or hydrocephalus.

Emergence reaction.

Treatment-emergent adverse reactions have occurred in approximately 12% of patients. The psychological manifestations vary in severity between pleasant dream-like states, vivid imagery, hallucinations, nightmares or illusions and delirium (often consisting of dissociative or floating sensations). In some cases, these states have been accompanied by confusion, excitement and irrational behaviour, which a few patients recall as an unpleasant experience. The duration ordinarily lasts no more than a few hours; in a few cases, however, recurrences have taken place up to 24 hours post-operatively. No residual psychological effects are known to have resulted from use of ketamine.
The incidence of these treatment-emergent adverse events is least in the young (15 years of age or less) and elderly (over 65 years of age) patient. Also they are less frequent when the drug is given intramuscularly. These reactions may be reduced if verbal, tactile and visual stimulation of the patient is minimised during the recovery period.
This does not preclude the monitoring of vital signs. In addition, the use of a small hypnotic dose of a short-acting or ultra-short-acting barbiturate may be required to terminate a severe treatment-emergent adverse reaction. The incidence of emergence reactions is reduced as experience with the drug is gained. When ketamine is used on an out-patient basis, the patient should not be released until recovery of anaesthesia is complete and should be accompanied by a responsible adult at discharge.

Cardiovascular.

Because of the substantial increase in myocardial oxygen consumption, ketamine should be used with caution in patients with hypovolemia, dehydration, or cardiac disease, especially coronary artery disease (e.g. congestive heart failure, myocardial ischaemia, and myocardial infarction). In addition, ketamine should be used with caution in patients with mild-to-moderate hypertension and tachyarrhythmias.
Cardiac function should be continually monitored during the procedure in patients found to have hypertension or cardiac decompensation.

Abuse potential.

Ketamine has been reported being used as a drug of abuse. Reports suggest that ketamine produces a variety of symptoms including, but not limited to, flashbacks, hallucinations, dysphoria, anxiety, insomnia, or disorientation. Ketamine dependence and tolerance may develop in individuals with a history of drug abuse or dependence. Therefore, ketamine should be prescribed and administered with caution.

Use in hepatic impairment.

In patients with significant hepatic impairment, the elimination of ketamine could potentially be delayed. Dose reductions should be considered in patients with cirrhosis or other types of liver impairment.

Use in renal impairment.

In patients with significant renal impairment, the elimination of ketamine could potentially be delayed.

Use in the elderly.

No data available.

Paediatric use.

Plasma half-life, clearance and volume of distribution (relative to body weight) are not significantly different between adults and children, although absorption following intramuscular injection is more rapid in the latter.1,2

Paediatric neurotoxicity.

Some published studies in children have observed cognitive deficits after repeated or prolonged exposures to anaesthetic agents early in life. These studies have substantial limitations, and it is not clear if the observed effects are due to the anaesthetic/analgesic/sedation drug administration or other factors such as the surgery or underlying illness.
Published animal studies of some anaesthetic/analgesic/sedation drugs have reported adverse effects on brain development in early life and late pregnancy. The clinical significance of these nonclinical finding is yet to be determined.
With inhalation or infusion of such drugs, exposure is longer than the period of inhalation or infusion. Depending on the drug and patient characteristics, as well as dosage, the elimination phase may be prolonged relative to the period of administration.

Effects on laboratory tests.

No data available.

4.5 Interactions with Other Medicines and Other Forms of Interactions

Halogenated hydrocarbon inhalational anaesthetics may prolong the half-life of ketamine; recovery from anaesthesia may be prolonged following concurrent use. Concurrent use of ketamine (especially in high doses or when rapidly administered) with halogenated anaesthetics can increase the risk of developing bradycardia, hypotension, or decreased cardiac output.
Diazepam is known to increase the half-life of ketamine and prolongs its pharmacodynamic effects. Dose adjustments may therefore be needed3.
Sympathomimetics (directly or indirectly acting) and vasopressin may enhance the sympathomimetic effects of ketamine3.
Prolonged recovery time may occur if barbiturates and/or narcotics are used concurrently with ketamine.
Benzodiazepines may prolong the half-life of ketamine; recovery from anaesthesia may be prolonged following concurrent use4.
Concomitant use with ergometrine may lead to an increase in blood pressure and co-administration of drugs with a hypertensive effect (e.g. ergometrine) should be avoided.3,5
Sustained rises in arterial pressure have been reported in patients receiving concomitant ketamine and thyroxine.5
Clinically significant apparent reduction in seizure threshold has been reported in patients receiving concomitant ketamine and theophylline or aminophylline.3,5 Unpredictable extensor-type seizures have been reported with concurrent administration of these agents.
There is no information available on the interactions between ketamine and antihypertensive agents. However, given the marked increase in arterial pressure following administration of ketamine, cardiac function should be monitored (see Section 4.4 Special Warnings and Precautions for Use).
Barbiturates and ketamine, being chemically incompatible because of precipitate formation, should not be injected from the same syringe.
Ketamine is clinically compatible with the commonly used general and local anaesthetic agents when an adequate respiratory exchange is maintained.
Ketamine may potentiate the neuromuscular blocking effects of atracurium and tubocurarine, including respiratory depression with apnoea.
The use of ketamine with other central nervous system (CNS) depressants (e.g. ethanol, phenothiazines, sedating H1-blockers, or skeletal muscle relaxants) can potentiate CNS depression and/or increase risk of developing respiratory depression. Reduced doses of ketamine may be required with concurrent administration of other anxiolytics, sedatives, and hypnotics.
Ketamine has been reported to antagonise the hypnotic effect of thiopental.
Patients taking thyroid hormones have an increased risk of developing hypertension and tachycardia when given ketamine.
Concomitant use of antihypertensive agents and ketamine increases the risk of developing hypotension.

4.6 Fertility, Pregnancy and Lactation

Effects on fertility.

No data available.
(Category B3)
Limited studies in animals have not shown that ketamine causes birth defects; however, it crosses the placenta. Histological changes in the heart (degeneration and oedema of cardiac muscle), liver (diffuse haemopoietic cell infiltration, parenchymal cell degeneration) and kidneys (proximal convoluted tubule degeneration) were observed in foetuses following administration of ketamine to pregnant rats during the period of organogenesis at doses similar to the maximum human dose, on a body surface area basis; a NOEL for these effects was not established. Ketamine administration to pregnant monkeys near term was associated with increased blood pCO2 and a dose-dependent respiratory depression in neonates, at a dose about one sixteenth the maximum human dose on a body surface area basis.
With the exception of administration during surgery for abdominal delivery or vaginal delivery, no controlled clinical studies in pregnancy have been conducted. The safe use of ketamine in pregnancy has not been established, and such use is not recommended.
Australian categorisation definition of Category B3: Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human foetus having been observed.
Studies in animals have shown evidence of an increased occurrence of fetal damage, the significance of which is considered uncertain in humans.
Published animal studies of some anaesthetic/analgesic/sedation drugs have reported adverse effects on brain development in early life and late pregnancy.
Published studies in pregnant and juvenile animals demonstrate that the use of anaesthetic/analgesic and sedation drugs that block NMDA receptors and/or potentiate GABA activity during the period of rapid brain growth or synaptogenesis may result in neuronal and oligodendrocyte cell loss in the developing brain and alterations in synaptic morphology and neurogenesis when used for longer than 3 hours. These studies included anaesthetic agents from a variety of drug classes.
 Ketamine is likely to be excreted in breast milk and therefore breastfeeding should be discontinued when ketamine is in use.

4.7 Effects on Ability to Drive and Use Machines

Patients should be cautioned that driving an automobile, operating machinery or engaging in other hazardous activities should not be undertaken for 24 hours or more (depending on dose and other drugs employed) after anaesthesia.

4.8 Adverse Effects (Undesirable Effects)

Reporting suspected adverse effects.

Reporting suspected adverse reactions after registration of the medicinal product is important. It allows continued monitoring of the benefit-risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions at http://www.tga.gov.au/reporting-problems and contact Apotex Medical Information enquiries/Adverse Drug Reaction Reporting on 1800 195 055.

Cardiovascular.

Blood pressure and pulse rate are frequently elevated following administration of ketamine. However, hypotension and bradycardia have been observed. Arrhythmia has also occurred.

Respiration.

Although respiration is frequently stimulated, severe depression of respiration or apnoea may occur following rapid intravenous administration of high doses of ketamine. Laryngospasm and other forms of airway obstruction have occurred during ketamine anaesthesia.

Eye.

Diplopia and nystagmus have been noted following ketamine administration. Ketamine may also cause a slight elevation in intraocular pressure measurement.

Psychological.

(See Section 4.4 Special Warnings and Precautions for Use, Emergence reaction.)

Neurological.

In some patients, enhanced skeletal muscle tone may be manifested by tonic and clonic movements, sometimes resembling seizures (see Section 4.2 Dose and Method of Administration).

Gastrointestinal.

Anorexia, nausea and vomiting have been observed. However, this is not usually severe and allows the great majority of patients to take liquids by mouth shortly after regaining consciousness (see Section 4.2 Dose and Method of Administration). Hypersalivation has also been observed.

Abuse potential.

(See Section 4.4 Special Warnings and Precautions for Use).

Immune system disorders.

Anaphylaxis has been observed.

General.

Local pain and exanthema at the injection site have infrequently been reported. Transient erythema and/or morbilliform rash have also been reported.

4.9 Overdose

Respiratory depression may occur with overdosage or too rapid rate of administration of ketamine, in which case, supportive ventilation should be employed. Mechanical support of respiration is preferred to administration of analeptics.
Ketamine has a wide margin of safety; several instances of unintentional administration of overdoses of ketamine (up to 10 times that usually required) have been followed by prolonged but complete recovery.
For information on the management of overdose, contact the Poison Information Centre on 131126 (Australia).

5 Pharmacological Properties

5.1 Pharmacodynamic Properties

Mechanism of action.

Ketamine is a rapid-acting, general anaesthetic producing an anaesthetic state characterised by profound analgesia, normal pharyngeal-laryngeal reflexes, normal or slightly enhanced skeletal muscle tone, cardiovascular and respiratory stimulation, and occasionally, a transient and minimal respiratory depression.
A patent airway is maintained, partly by virtue of relatively unimpaired pharyngeal and laryngeal reflexes (see Section 4.4 Special Warnings and Precautions for Use).
The anaesthetic state produced by ketamine has been termed 'dissociative anaesthesia' in that it appears to selectively interrupt association pathways of the brain before producing somaesthetic sensory blockade. Ketamine may selectively depress the thalamoneocortical system before significantly obtunding the more ancient cerebral centres and pathways (reticular-activating and limbic systems).
Elevation of blood pressure begins shortly after injection, reaches a maximum within a few minutes and usually returns to pre-anaesthetic values within 15 minutes after injection. The median peak rise has ranged from 20 to 25% of pre-anaesthetic values.

Clinical trials.

Ketamine (as hydrochloride) has been studied in over 12,000 operative and diagnostic procedures involving over 10,000 patients from 105 separate studies. During the course of these studies, ketamine was administered as the sole agent, as induction for other general anaesthetic agents, or to supplement low potency agents. In these studies, the anaesthesia was rated either "excellent" or "good" by the anaesthetist and the surgeon at 90% and 93% respectively. In a second method of evaluation, the anaesthesia was rated "adequate" in at least 90% and "inadequate" in 10% or less of procedures. Specific areas of application have included the following:
debridement, painful dressings and skin grafting in burn patients as well as other superficial surgical procedures;
neurodiagnostic procedures such as pneumoencephalograms, ventriculograms, myelograms and lumbar punctures;
diagnostic and operative procedures of the eye, ear, nose and mouth including dental extractions;
diagnostic and operative procedures of the pharynx, larynx or bronchial tree;

Note.

Muscle relaxants with proper attention to respiration, may be required (see Section 4.4 Special Warnings and Precautions for Use).
sigmoidoscopy and minor surgery of the anus and rectum and circumcision;
extraperitoneal procedures used in gynaecology, such as dilation and curettage;
orthopaedic procedures such as closed reductions, manipulations, femoral pinning, amputations and biopsies;
as an anaesthetic in poor-risk patients with depression of vital functions;
in procedures where the intramuscular route of administration is preferred;
in cardiac catheterisation procedures.

5.2 Pharmacokinetic Properties

Absorption.

Ketamine is rapidly absorbed following parenteral administration. Peak plasma levels averaged 0.75 microgram/mL and CSF levels were about 0.2 microgram/mL one hour after dosing.6 The plasma half-life is in the range of 2 to 4 hours.7,8,9 After IM administration (absorption half-life 2-17 minutes) it is up to 93% bioavailable.6

Distribution.

Ketamine (as hydrochloride) is rapidly and extensively distributed throughout the body into highly perfused tissues including the brain.8,9 Mean volume of distribution is reported to range from approximately 1 to 3 L/kg, and the distribution half-life is approximately 7 to 11 minutes. Ketamine (as hydrochloride) is approximately 20-50% bound to plasma proteins.4 Ketamine is likely to be excreted in breast milk, but this is unlikely to be clinically relevant. The drug crosses the placenta in induction doses10 (see Section 4.6 Fertility, Pregnancy and Lactation).

Metabolism.4

Ketamine undergoes extensive hepatic metabolism. The biotransformation includes N-dealkylation to norketamine (metabolite I), hydroxylation of the cyclohexone ring (metabolites III and IV), conjugation with glucuronic acid and dehydration of the hydroxylated metabolites to form the cyclohexene derivative (metabolite II). Norketamine (metabolite I) has about 1/6 of the potency of ketamine and is formed at concentrations in the plasma similar to those of the parent compound.

Excretion.

After intravenous bolus administration, ketamine shows a bi- or triexponential pattern of elimination. The alpha phase lasts about 45 minutes with a half-life of 10 to 15 minutes. This first phase, which represents the anaesthetic action of ketamine, is terminated by redistribution from the CNS to peripheral tissues and hepatic biotransformation to an active metabolite. The beta phase half-life is about 2.5 hours.7,8,9 About 90% of ketamine is excreted in the urine, mostly as metabolites, with only about 2 to 4% as the unchanged drug. Approximately 5% is recovered in the faeces.11 The renal clearance of ketamine hydrochloride is 15 ± 5 mL/min/kg.12

Paediatric patients.

Plasma half-life, clearance and volume of distribution (relative to body weight) are not significantly different between adults and children, although absorption following intramuscular injection is more rapid in the latter.1,2

5.3 Preclinical Safety Data

Genotoxicity.

No data available.

Carcinogenicity.

No data available.

6 Pharmaceutical Particulars

6.1 List of Excipients

Ketamine also contains water for injections.

6.2 Incompatibilities

Barbiturates and ketamine, being chemically incompatible because of precipitate formation, should not be injected from the same syringe.

6.3 Shelf Life

In Australia, information on the shelf life can be found on the public summary of the Australian Register of Therapeutic Goods (ARTG). The expiry date can be found on the packaging.

6.4 Special Precautions for Storage

Store below 30°C. Protect from light.
Ketamine should not be used if the solution is deeply coloured and/or contains particulate matter.

6.5 Nature and Contents of Container

Ketamine APOTEX 200 mg/2 mL solution for injection, AUST R 219040: 2 mL ampoule pack (Type I clear glass). Available in packages of 5 ampoules.

6.6 Special Precautions for Disposal

In Australia, any used medicine or waste material should be disposed of in accordance with local requirements.

6.7 Physicochemical Properties

Ketamine is freely soluble in water and methanol and is soluble in ethanol (96%).
Chemical Name: (2RS)-2-(2-Chlorophenyl)-2-(methylamino) cyclohexanone hydrochloride.
Molecular Formula: C13H16ClNO.HCl.
Molecular Weight: 274.2.

Chemical structure.


CAS number.

1867-66-9.

References

1 Nimmo WS, et al. Pharmacokinetics of ketamine in children. Br J Anaesth 1982; 14: 144P.
2 Grant IS, et al. Ketamine disposition in adults and children Br J Anaesth 1983, 55: 1107-11.
3 2.5 Clinical overview updates to section 4.5 Interaction With Other Medicinal Products and Other Forms of Interaction of the Core Data Sheet November 2016.
4 Therapeutic Drugs. Edited by Sir Colin Dollery, 1991, Vol 2: K7-13.
5 Martindale The Complete Drug Reference, Micromedex Healthcare series Vol. 105 Inc Copyright 2000 Pharmaceutical Press.
6 Clements JA, Nimmo WS, Grant IS. Bioavailability, pharmacokinetics and analgesic activity of ketamine in humans. J Pharm Sci 1982; 71: 539-41.
7 Clements JA, Nimmo WS. Pharmacokinetics and analgesic effects of ketamine in man. Br J Anaesth 1981; 53: 27-30.
8 Grant IS, et al. Pharmacokinetics and analgesic affects of IM and oral ketamine. Br. J Anaesth 1981; 53: 805-9.
9 Wieber J, Gryler RD, Hengstmann JH, Dengler HJ. Pharmacokinetics of ketamine in man. Anaesthesist 1975; 24: 260-6.
10 Little B, Chang T, Chaucet L, et al. A study of ketamine as an obstetrical anesthetic. Am J Obstet Gynecol 1972; 113: 247-58.
11 United States Pharmacopeia Dispensing Information, 1998, 18th Edition, pg 1775-7.
12 Geisslinger G, et al. Pharmacokinetics and pharmacodynamics of ketamine enantiomers in surgical patients using a stereoselective analytical method. Br J Anaesth 1993, 70: 666-71.

7 Medicine Schedule (Poisons Standard)

S8.

Summary Table of Changes