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Drug Information
Pharmacokinetics |
Indication & Dosage | Action
| Interaction
Adverse
Effect & Precautions |
Brands available in Market
Pharmacokinetics
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 ketamine’s
anaesthetic action, is terminated by redistribution from the CNS to
peripheral tissues and hepatic biotransformation to an active metabolite
norketamine. Other metabolic pathways include hydroxylation of the
cyclohexone ring and conjugation with glucuronic acid. The beta phase
half-life is about 2.5 hours. It is excreted mainly in the urine as
metabolites. Ketamine crosses the placenta.
Indication
& Dosage
Parenteral
DIAGNOSTIC AND OPERATIVE PROCEDURES INCLUDING, NEURODIAGNOSTIC,
ORTHOPAEDIC, ENT, DENTAL, GYNAECHOLOGICAL, AND CARDIAC CATHETERISATION
PROCEDURES WHERE SKELETAL MUSCLE RELAXATIONIS NOT REQUIRED. INDUCTION
BEFORE ADMINISTERING OTHER GENERAL ANAESTHETICS: Induction: IV
1-4.5mg/kg over a period f 60 seconds. Alternatively, in adults 1-2mg/kg
given IV at 0.5mg/kg/min+diazepam 2-5mg by separate IV inj over 60 secs
upto total of 15mg.
IM can be used as an alternative to IV route: 6.5-13mg/kg.
Maintenance: Adusted according to patients’ anaesthetic reponse and use
of other agents. Half the total induction dose may be repeated as needed
to maintain anaesthesia.
Action
General anaesthetic with a rapid action. Pharyngeal and laryngeal
reflexes are not impaired and so a patent airway is maintained. Produces
a “dissociative anaesthesia:. Blood pressure is increased returning
to preinjection values 15 min after the injection. Wide sagety margin
Interaction
Barbiturates or narcotics:
Prolonged recovery time may occur.
Halothane: Blocks cardiovascular stimulatory effects of ketamine leading
to decreased cardiac output, blood pressure and pulse rate.
Tubocurarine and non deplarizing muscle relaxants: Increased
neuromuscular effects, leading to prolonged resp. depression.
Thyroid hormones: Concurrent use may produce hypertension and
tachycardia.
Aminophylline: reduces seizure threshold.
Alcohol: Resistance to ketamine anaesthesia; exaggerated psycohosomatic
effects during recovery from anaesthesia.
Oxytocin, ergometrine: Potentiate cardiovascular adverse effects.
Benzodiazepines:Reduced Incidence of and severity of psychotomimetics
and cardiovascular resposes.
Adverse Effect
&Precaution
Arrythmia illusions,
tachycardia, hallucination, respiratory depression, diplopia,
hypotension, vivid dreams, nystagmus, nausea, anorexia, vomiting, clonic
and tonic movements.
Precaution: To be given by
trained anaesthetist. Pulse and BP to be monitored. Over doasge or rapid
injection may result in respiratory depression
Pregnancy: Contraindicated
Breast Feeding: Use with caution.
Man: May be used.
