ANESTHETICS-Contd...
DISSOCIATIVE AGENTS AND HALLUCINOGENS
These agents are employed as adjuncts with the inhalation agents to attain anesthesia rapidly. These agents are psychotic products and induce withdrawal symptoms, through hallucinations and delusions. They are usually given by I.V.routes.
1.PROPOFOL (Diprivan)
This drug is clinically used for the induction of anesthesia.
Pharmacology:-
This drug is very similar to the opioid thiopental as high-fat solubility. Hence it easily crosses the blood-brain barrier to produce ultrafast CNS effects. Higher affinity and readily distribute into highly vascularised tissues like the brain followed by rapid redistributing back into the blood. Hence its onset of action is ultra-fast with a short duration of action.
Benefits Over Thiopental
1. Ultra-fast in the induction of anesthesia similar to thiopental but recovery is very sooner than thiopental.
2.Less nausea and vomiting
3.No cumulative effect or delay in recovery even after a prolonged infusion.
Metabolism and Kinetics
Metabolized by liver-enzymes like CYP-450-2-B6 through glucuronidation and extrahepatic enzymes present in kidneys. The metabolism is very faster than that of thiopental. Usually the I.V. anesthetics are not eliminated through lungs. The metabolites are excreted in the urine.
Side Effects
1.Hypotension
2.Negative inotropic effects(Weaken the muscle contractions especially that of the heart)
3.The pain of injection.
KETAMINE
Ketamine because of the prominent cardiovascular support it is mostly used in relieving the patients from fear of surgery and radiotherapies and post-operative traumas.
It is very useful in relieving traumas of children during dressing changes of burns and radiological procedures.
Ketamine is a dissociative agent to produce anesthesia associated with catatonia, amnesia, and analgesia without actual loss of consciousness.
Pharmacology
Ketamine's cardiovascular support during anesthesia is accounted for by its sympathetic stimulant action. Ketamine causes an increase in catecholamine releases and thereby causes a series of sympathomimetic effects such as increased heart rate, B.P, and cardiac output.
Warning:-
Ketamine should not be given as an analgesic in patients with head injuries as it increases cerebral blood flow oxygen consumption and intracranial pressure.
Side Effects
1.Disorientation
2.Sensory and perceptual illusions
3.Vivid and unpleasant dreams.
The side effects can be minimized or nullified by the concomitant or 5 to 10 minutes prior administration of diazepam
Routes of Administration:-
1. Intra muscularly
2.Intra venously.
