Medically reviewed by Meghan Maynard Harlan. Last updated on August 18, 2025
Parke-Davis
Ketamine HCl
Parenteral General Anesthetic
Action And Clinical Pharmacology: Ketamine is a cataleptic, analgesic and anesthetic agent devoid of sedative or hypnotic properties, distinguishing it from the commonly used barbiturates.
It produces an anesthetic state characterized by profound analgesia, normal pharyngeal-laryngeal reflexes and normal or slightly enhanced skeletal muscle tone. Mild cardiac stimulation and occasionally respiratory depression occur.
The anesthetic state produced by ketamine has been termed dissociative anesthesia’ in that it appears to selectively interrupt association pathways of the brain before producing somesthetic sensory blockade. It may selectively depress the thalamoneocortical system before significantly obtunding the more ancient cerebral centres and pathways (reticular activating and limbic systems).
Ketamine is rapidly absorbed following parenteral administration. Animal experiments indicated that ketamine was rapidly distributed into body tissues, with relatively high concentrations appearing in body fat, liver, lung and brain; lower concentrations were found in the heart, skeletal muscle and blood plasma. Placental transfer of the drug was found to occur in pregnant dogs and monkeys. No significant degree of binding to serum albumin was found with ketamine.
Studies in human subjects resulted in the mean recovery of 91% of the dose in the urine and 3% in the feces. Peak plasma levels averaged about 0.75 µg/mL and CSF levels were about 0.2 µg/mL, 1 hour after dosing.
Ketamine undergoes N-demethylation and hydroxylation of the cyclohexanone ring, with the formation of water-soluble conjugates which are excreted in the urine. Further oxidation also occurs with the formation of a cyclohexanone derivative. The unconjugated N-demethylated metabolite was found to be less than one sixth as potent as ketamine. The unconjugated demethyl cyclohexanone derivative was found to be less than one tenth as potent as ketamine. Repeated doses of ketamine administered to animals did not produce any detectable increase in microsomal enzyme activity.
Indications And Clinical Uses: As the sole anesthetic agent for recommended diagnostic and surgical procedures. Although best suited to short procedures, ketamine can be used, with additional doses, for longer procedures.
Note: If skeletal muscle relaxation is desired, a muscle relaxant should be used. In surgical procedures involving visceral pain pathways, ketamine should be supplemented with an agent which obtunds visceral pain.
For the induction of anesthesia prior to the administration of other general anesthetic agents.
To supplement low potency agents such as nitrous oxide.
Contra-Indications: History of cerebrovascular accident; cases where a significant elevation of blood pressure would constitute a serious hazard, such as in patients with severe hypertension; severe cardiac decompensation; in surgery of the pharynx, larynx, or bronchial tree unless adequate muscle relaxants are used; hypersensitivity to the drug.
Precautions: Ketamine is for use only by or under the direction of physicians and oral surgeons experienced in administering general anesthetics and in maintenance of an airway and in the control of respiration.
Cardiac function should be continually monitored during the procedure in patients found to have hypertension or cardiac decompensation.
Barbiturates and ketamine, being chemically incompatible because of precipitate formation, should not be injected from the same syringe.
Barbiturates and narcotics, being CNS depressants, may prolong recovery time if used concurrently with ketamine.
Respiratory depression may occur with overdosage or too rapid administration of ketamine, in which case supportive ventilation should be employed. Mechanical support of respiration is preferred to administration of analeptics.
An increase in cerebrospinal fluid pressure has been reported following the administration of ketamine. Therefore, special caution should be exercised when using ketamine in cases with preexisting elevated intracranial pressure, and in those cases with normal intracranial pressure in which, in the opinion of the physician, a rise in such pressure would entail special risks.
Pregnancy: Although animal studies of teratogenicity, fertility, and reproduction indicated the safety of ketamine, its safe use in human pregnancy has not been established.
Because pharyngeal reflexes are maintained, mechanical stimulation of the pharynx should be avoided unless adequate muscle relaxants are used. Precautions should be taken in patients with upper respiratory infection because of the increased danger of respiratory difficulties, such as laryngospasm, in these cases.
Resuscitative equipment should be available and ready for use.
The initial i.v. dose should be administered over a period of 60 seconds. More rapid administration may result in respiratory depression and enhanced pressor response.
During recovery from anesthesia the patient may go through a phase of emergence reaction characterized by vivid dreams, confusion (with or without psychomotor activity), excitement, irrational behavior and occasionally hallucinations. In 12 283 procedures, postanesthetic emergence responses were broken down into parameters and the incidence of reaction is shown in Table I.
Table I indicates that emergence reactions are more common in the 15 to 35 year group.
The reactions tabled above occurred in the majority of instances in patients in whom droperidol or diazepam had not been used as premedications.
Long-term follow up observations of 221 patients (140 with ketamine, 81 with other anesthetic agents) have not revealed any residual psychological effects.
The incidence of emergence reactions may be reduced if verbal, tactile and visual stimulation of the patient is avoided during the recovery period, certainly until the patient is fully conscious and able to be returned to the ward. These precautions do not preclude the monitoring of vital signs.
Hypnotic doses of ultrashort acting thiobarbiturates (50 to 100 mg i.v.) can be used to terminate severe emergence reactions. Diazepam, 5 mg i.v., has also been used to terminate emergence reactions.
During anesthesia the eyelids may remain retracted. During recovery they close. Premature stimulation during recovery in the presence of nystagmus and diplopia may precipitate retching, nausea, or frank vomiting.
Purposeless movements of extremities may occur during the course of anesthesia. These movements do not imply a light plane and are not indicative of the need for additional doses of the anesthetic.
Adverse Reactions: Cardiovascular: Ketamine may cause a temporary augmentation of the pulse rate and blood pressure. Elevation of blood pressure begins shortly after injection, reaches a maximum within a few minutes and usually returns to preanesthetic values within 15 minutes after injection. The median peak rise has ranged from 20 to 25% of preanesthetic values. Depending on the condition of the patient, this elevation of blood pressure may be considered a beneficial effect, or in others, an adverse reaction. If elevation of blood pressure would be considered adverse to the patient, the benefit to risk ratio should be carefully determined. Maintaining or moderately increasing blood pressure may be beneficial to some patients, as those in shock or those in whom reduction in blood pressure is contraindicated (see Precautions).
Hypotension, arrhythmia, and bradycardia have rarely been observed.
Respiratory: Respiration is not greatly affected. Mild stimulation sometimes occurs, but respiratory depression, moderate and transient (less than 30 seconds), also occurs in a small percentage of patients. Laryngospasm and other forms of airway obstruction have occurred during ketamine anesthesia.
Psyche: During emergence from anesthesia the patient may go through a phase of vivid dreaming, with or without psychomotor activity, manifested by confusion and irrational behavior (see Precautions). These reactions are transient and have been observed less often in children than in adults. They appear to be similar to those observed following the use of other general anesthetic agents.
Tonic and clonic movements sometimes resembling convulsive seizures have occurred in a few patients receiving ketamine. These movements do not imply a light plane and are not indicative of the need for additional doses of the anesthetic.
EEG recordings were made in 14 patients receiving ketamine. Although 1 of these patients exhibited slight twitching of the arms and legs, none showed EEG changes to suggest seizure reactions.
Epileptiform attacks have been observed in a few patients following ketamine administration. However, ketamine has been used successfully in patients known to be suffering from epilepsy.
Gastrointestinal: Anorexia, nausea, or vomiting are minimal, allowing the great majority of patients to take liquids by mouth shortly after regaining consciousness.
Increased salivation may occur unless an antisialagogue is used.
Ophthalmic: Blurred vision and nystagmus are not uncommon findings during the recovery period.
Ketamine causes a small transient increase in intraocular pressure. However, it has been used in patients with glaucoma without causing any deterioration in this condition.
General: Except for rare reports of local pain and exanthema at the injection site, ketamine is well tolerated by the patient when administered either by the i.v. or i.m. route. Transient erythema and morbilliform rash have been reported.
Symptoms And Treatment Of Overdose: Symptoms and Treatment: Respiratory depression can result from an overdosage of ketamine. Supportive ventilation should be employed. Mechanical support of respiration that will maintain adequate blood oxygen saturation and carbon dioxide elimination 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 of the usually required dose) have been followed by prolonged but complete recovery.
Dosage And Administration: Ketamine has been safely used alone when the stomach was not empty. However, since the need to use supplementary anesthetic or muscle relaxant agents cannot always be predicated, it is preferable not to give anything by mouth for at least six hours before elective surgery. Ketamine is recommended for use in patients whose stomach is not empty when in the judgment of the physician the benefits of the drug outweigh the possible hazards.
Atropine, scopolamine, or other antisecretory agents should be given at an appropriate interval prior to induction.
Certain drugs such as droperidol or diazepam have been used i.m. in an attempt to reduce the incidence of emergence reactions: sufficient data have not yet been accumulated to constitute thorough documentation. The incidence of emergence reactions is reduced as experience with the drug is gained.
As with other general anesthetic agents, the individual response to ketamine is somewhat varied depending on the dose, route of administration, and age of patient, so that dosage recommendation cannot be absolutely fixed. The drug should be titrated to the patient’s requirements.
Because of rapid induction following the initial i.v. injection, the patient should be in a supported position during administration.
The onset of action of ketamine is rapid; an i.v. dose of 2 mg/kg (1 mg/lb) usually produces surgical anesthesia within 30 seconds after injections, with the anesthetic effect usually lasting 5 to 10 minutes. If a longer effect is desired, additional increments can be administered i.v. or i.m. to maintain anesthesia without producing significant cumulative effects.
I.M. doses, from experience primarily in children, in a range of 9 to 13 mg/kg (4 to 6 mg/lb) usually produce surgical anesthesia within 3 to 4 minutes following injection, with the anesthetic effect usually lasting 12 to 25 minutes.
Ketamine as sole anesthetic agent:
Induction: I.V.: The initial dose of ketamine administered i.v. may range from 1.0 to 4.5 mg/kg (0.5 to 2 mg/lb). The average amount required to produce 5 to 10 minutes of surgical anesthesia has been 2.0 mg/kg (1 mg/lb). Ketamine should be administered slowly (over a period of 60 seconds). More rapid administration may result in respiratory depression and enhanced pressor response.
I.M.: The initial dose of ketamine administered i.m. may range from 6.5 to 13.0 mg/kg (3 to 6 mg/lb). A dose of 10 mg/kg (5 mg/lb) will usually produce 12 to 25 minutes of surgical anesthesia.)
Maintenance: Increments of 50% to the full induction dose, either i.v. or i.m. may be repeated as needed for maintenance of anesthesia. Nystagmus, movements in response to stimulation, and vocalization may indicate lightening of anesthesia.
Ketamine used prior to administration of other general anesthetics: Ketamine is clinically compatible with the commonly used general and local anesthetic agents when an adequate respiratory exchange is maintained.
When ketamine is used as an induction agent, prior to the administration of other general anesthetic agents:
1. The full induction dose of ketamine should be given i.v. over 60 seconds.
2. At the completion of the induction dose of ketamine, the anesthetist should proceed immediately with the chosen general anesthetic procedure. A second dose of ketamine (half the original induction dose) may be required at 5 to 8 minutes following the initial induction dose when using an agent such as methoxyflurane where some considerable time is required for full surgical anesthesia to be established with the gaseous anesthetic. Otherwise lightening in the depth of anesthesia may occur and the patient may enter the stage of excitement, associated with vocalization and purposeful movements.
Recovery: Following the procedure the patient should be observed but left undisturbed. This does not preclude the monitoring of vital signs.
Availability And Storage: 10 mg: Each mL contains: ketamine HCl equivalent to 10 mg ketamine base. Steri-Vials of 20 mL.
50 mg: Each mL contains: ketamine HCl equivalent to 50 mg ketamine base. Steri-Vials of 10 mL.
The solution for i.v. or i.m. use contains 1:10 000 benzethonium chloride as a preservative (pH 3.5 to 5.5). The 10 mg/mL solution has been made isotonic with sodium chloride (2.6 mg/5 mL).
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