Question

What are the pharmacokinetics of Ketamine Hydrocholoride?

What are the pharmacodynamics of Ketamine Hyrdrochloride?

Answer 1

1. pharmacokinetics of ketamine hydrochloride

pharmacokinetics means the study of the bodily absorption, distribution, metabolism, and excretion of drugs.

• ABSORPTION :

Ketamine is absorbed by intravenous, intramuscular, oral, and topical routes due to both its water and lipid solubilities.Ketamine absorption is very rapid and the bioavailability is around 93%. After the first pass metabolism, only 17% of the administered dose is absorbed. It distributes very rapidly and presents a distribution half-life of 1.95 min. The Cmax levels at peak reach 0.75 mcg/ml in plasma and 0.2 mcg/ml in cerebrospinal fluid.

• DITRIBUTION:

Ketamine is rapidly distributed and, due to its high lipophilicity. also this drug can cross BBB(blood brain barrier) Its distribution half-life is about 7 to 11 minutes.The plasma protein binding of ketamine is relatively low at 12 to 47%.

• METABOLISM:

In a oral dose it goes in to first pass metabolism and biotransfer in liver.The duration of action of ketamine in a clinical setting is 0.5 to 2 hours intramuscularly and 4 to 6 hours orally.

• ELIMINATION:

Ketamine is eliminated about 90% in urine and about 1 to 5% in feces

2.PHARMACODYNAMICS OF KETAMINE HYDROCHLORIDE

Pharmacodynamics means the branch of pharmacology concerned with the effects of drugs and the mechanism of their action.

MECHANISM OF ACTION:

Ketamine is a rapid-acting general anesthetic producing an anesthetic state characterized 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.

The anesthetic state produced by Ketamine has been termed as 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 centers and pathways (reticular-activating and limbic systems).

Ketamine enhances descending inhibiting serotoninergic pathways and can exert antidepressive effects. These effects are seen in concentrations ten times lower than the needed concentration for anesthetic proposes.

The effect of ketamine can be described as analgesic by the prevention of central sensitization in dorsal horn neurons as well as by the inhibition on the synthesis of nitric oxide. Ketamine can present cardiovascular changes and bronchodilatation.

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