Pharmacokinetics of Ketamine: Administration, Distribution, Metabolism and Elimination

This presentation provides an overview of the pharmacokinetics of Ketamine, a Schedule 3 compound. It covers the different routes of administration, absorption rates, distribution to various parts of the body, duration of action, metabolism by the liver, and elimination through renal excretion. The presentation also highlights the major and minor enzymes involved in the metabolism of Ketamine and its metabolites. Additionally, it discusses the standard toxicology tests used to detect Ketamine and its metabolites.

KETAMINE

Administration
•Ketamine is classified as a Schedule 3
Compound. Ketamine is orally administered
whereby 16% of the administered drug is
absorbed.
•This means that about 5 mg of the administered
30mg is orally absorbed. Other routes of
Ketamine administration include intravenous,
subcutaneous and intramuscular (Harold, 2015).

Distribution
• Ketamine is distributed to all other parts of the body
through the bloodstream. The drug then enters the heart
where it is pumped to all the parts of the body including
the brain.
• Ketamine has a varied duration of action depending on the
route of administration whereby oral ketamine takes 6
hours, intramuscular is 2 hours and intravenous takes 1
hour. Peak blood levels are reached after 20 minutes after
oral ingestion.
• When used as an intravenous injection, it is rapidly
distributed to the brain and other organs and the effects are
seen in seconds (Katzung, Masters & Trevor, 2012).

Metabolism
•The drug is mostly metabolized by the liver
through N-demethylation through hepatic phase
1 and phase 2.
•The major enzyme involved is CYP3A4 while
the two minor enzymes are CYP2C9 and
CYP2B6.
•Ketamine metabolites include norketamine,
hydroxynorketamine, dehydronorketamine and
conjugates (Harold, 2015).

Elimination
• Elimination of Ketamine is mostly renal whereby almost
90% of the drug is really excreted (Katzung & Trevor,
2015). The elimination half-life of ketamine is 3-4 hours
while that of norketamine is 12 hours.
• The drug is greatly biotransformed by the liver before its
elimination. The drug is also excreted in faeces in small
amounts of about 3%, milk, sweat and expired air
(Marland, Ellerton, Andolfatto, Strapazzon, Thomassen,
Brandner & Paal, 2013).
• The Standard toxicology tests that are usually put into use
do not deter Ketamine if a “date rape” is suspected a
specific toxicology test is conducted to detect the initial
drug or its metabolites.

References
• Harold E.D, (2015). Concepts of Chemical Dependency 9th
Edition pp.
• Katzung, B. G., Masters, S. B., & Trevor, A. J.
(2012). Basic and Clinical Pharmacology (LANGE Basic
Science). McGraw-Hill Education.
• Katzung, B. G., & Trevor, A. J. (Eds.). (2015). Basic &
clinical pharmacology (pp. 753-756). New York, NY:
McGraw-Hill.
• Marland, S., Ellerton, J., Andolfatto, G., Strapazzon, G.,
Thomassen, O., Brandner, B., ... & Paal, P. (2013).
Ketamine: use in anesthesia. CNS neuroscience &
therapeutics, 19(6), 381-389.