Ketamine Hydrochloride

Trade Names:Ketalar- Injection, solution 10 mg/mL- Injection, solution 50 mg/mL- Injection, solution 100 mg/mL

Trade Names:Ketamine- Injection, solution 10 mg/mL- Injection, solution 50 mg/mL- Injection, solution 100 mg/mL

Pharmacology

Produces rapid-acting anesthetic state with profound analgesia, normal pharyngeal-laryngeal reflexes, normal or slightly enhanced skeletal muscle tone, cardiovascular and respiratory stimulation, and, occasionally, transient and minimal respiratory depression.

Pharmacokinetics

Absorption

Ketamine is rapidly absorbed. Mean C _max is 0.75 mcg/mL. T _max is 1 h.

Distribution

Distribution half-life is approximately 10 to 15 min.

Metabolism

Undergoes N-dealkylation, hydroxylation of cyclohexone ring, conjugation with glucuronic acid, and dehydration of the hydroxylated metabolites to form the cyclohexene derivative. The metabolite is about one-third as active as ketamine.

Elimination

The beta phase half-life of ketamine is 2.5 h. Approximately 91% is excreted in urine and 3% in feces.

Onset

Onset is 30 sec (IV) and 3 to 4 min (IM).

Duration

Duration is 5 to 10 min (IV) and 12 to 25 min (IM).

Indications and Usage

Diagnostic and surgical procedures that do not require skeletal muscle relaxation; induction of anesthesia; supplementation of low-potency agents, such as nitrous oxide.

Unlabeled Uses

Prevention of anesthesia-induced shivering.

Contraindications

Patients in whom significant BP elevation would be a serious hazard; hypersensitivity to the drug.

Dosage and Administration

IV Initial: 1 to 4.5 mg/kg via slow infusion (over 60 sec); usual dose for 5- to 10-min anesthesia: 2 mg/kg. Alternatively, 1 to 2 mg/kg at a rate of 0.5 mg/kg/min, augmented with diazepam IV 2 to 5 mg. Maintenance: One-half to full induction dose, repeated as needed. Alternatively, adults induced with ketamine augmented with IV diazepam may receive 0.1 to 0.5 mg/min by slow microdrip infusion, augmented with diazepam 2 to 5 mg IV as needed. IM Initial: 6.5 to 13 mg/kg. Maintenance: One-half to full induction dose, repeated as needed.

General Advice

• The 100 mg/mL concentration should not be injected IV without proper dilution. It is recommended that the drug be diluted with an equal volume of sterile water for injection, isotonic sodium chloride solution, or dextrose 5% in water.
• Because of rapid induction following the initial IV injection, the patient should be in a supported position during administration.
• Administer IV slowly (over a period of 60 sec). More rapid administration may result in respiratory depression and enhanced pressor response.
• To prepare a dilute solution containing 1 mg/mL, transfer 10 mL (50 mg/mL concentration) or 5 mL (100 mg/mL concentration) to 500 mL of dextrose 5% injection or sodium chloride 0.9% injection and mix well. If fluid restriction is required, add ketamine as described previously to a 250 mL infusion to provide a final concentration of 2 mg/mL.
• Ketamine 10 mg/mL is not recommended for dilution.
• Ketamine is physically incompatible with diazepam and barbiturates.
• Give atropine, scopolamine, or another drying agent at an appropriate interval prior to induction.

Storage/Stability

Store vials at controlled room temperature (68° to 77°F). Protect from light.

Drug Interactions

Decreased cardiac output, BP, and pulse.

Increased neuromuscular effects, resulting in prolonged respiratory depression.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Arrhythmia, bradycardia, elevated blood pressure and heart rate, hypotension.

CNS

Enhanced skeletal muscle tone manifested by tonic and clonic movement.

Confusion, delirium, excitement, hallucinations, irrational behavior, pleasant dream-like state, vivid imagery.

Dermatologic

Morbilliform rash, transient erythema.

EENT

Diplopia, increased intraocular pressure, nystagmus.

GI

Anorexia, nausea, vomiting.

Local

Local pain and exanthema at injection site.

Respiratory

Apnea after rapid injection, laryngospasm, other airway obstruction, respiratory stimulation, severe respiratory depression.

Precautions

Pregnancy

Category B .

Lactation

Undetermined.

Children

Safety and efficacy in children younger than 16 yr of age have not been established.

Elderly

Use with caution, usually starting at the low end of the dosing range.

Alcohol

Use with caution in chronic alcoholic and acutely alcohol-intoxicated patients.

Cerebrospinal fluid pressure

Cerebrospinal fluid pressure increase has been reported following administration.

Hypertension or cardiac decompensation

In patients with these conditions, monitor function continuously during procedure.

Respiratory effects

May occur with overdosage or too rapid a rate of administration.

Respiratory surgery/diagnostic procedures

Do not use in surgery or diagnostic procedures of the pharynx, larynx, or bronchial tree. Do not administer ketamine alone because pharyngeal and laryngeal reflexes are usually active. Muscle relaxants, with proper attention to respiration, may be required.

Visceral pain

In surgical procedures involving visceral pain pathways, supplement with an agent that obtunds visceral pain.

Overdosage

Symptoms

Respiratory depression.

Patient Information

• Advise patient that neurologic effects may persist for 24 h after anesthesia. Advise patient to use caution during this period while driving or performing other tasks requiring mental alertness.

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