By. Dr. J.M. Nguta, PhD (Pharmacol/Toxicol
Anaesthetics and Life
 "The wonderful dream that pain has been taken away
from us has become reality. Pain, the highest
consciousness of our earthly existence, the most
distinct sensation of the imperfection of our body,
must now bow before the power of the human mind,
before the power of ether vapor."Johann Friedrich
Dieffenbach (1795-1847), -German pioneer plastic
surgeon
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Anaesthesia and life
 Not too many medical revelations could be termed as
significant and elementary as the discovery and
development of Anesthesia. It was a turning point for
the world of medicine and surgery, as the physicians
and surgeons could concentrate on the case at hand
without either worrying about the safety of the patient
in terms of enduring pain or the shrieks that shook the
hospital buildings
Read more: http://explorable.com/history-ofanesthesia.html#ixzz29xboXirg
Anesthetics-What are they?
 Used to reduce sensory awareness and to suppress
reflexes sufficiently to permit the conduct of surgery.
 Anesthetics are agents which eliminate body sensation
Anesthetics/Anesthesia
 The term anesthesia is now broadly applied in the
surgical field to a complex procedure by which the
patient is prepared psychologically for the operation
and then rendered insensible to all feelings in the
operation area, oxygenation of the blood is maintained
at optimum levels, pharmacological means are used to
keep the field of surgery clear of blood and muscle
tone is decreased so that manipulations may be carried
out easily and quickly.
Introduction/Why this topic
 If you search for anesthetics:
Google search: 4, 570,000 Citations
Pubmed:
277, 827
Citations
Sciverse:
180, 413
Citations
Introd.
 What are anesthetics?
 How are they classified?
 Why should we use them in Veterinary practice?
 How are they used with ancillary therapeutics?
 Examples of commonly used anesthetics
General anesthetics
 What are Gas? (Loss of sensation; abolition of
voluntary motor response; also induce sleep)
 Provision of: Analgesia; Amnesia; loss of
consciousness; muscle relaxation; abolition of
voluntary motor response)
Classification of GAs
 How are they classified?
 Examples in various classes Commonly used anesthetics in various classes-
Local anaesthetics
 Local anesthetics are drugs which reversibly block
nerve conduction beyond the point of application,
when applied locally in an appropriate concentration.
Thus, local anesthesia is a drug induced reversible
blockade of nerve impulses in a restricted region of the
body.
Classification of LAs
 Based on chemical structure:
1.Esters of benzoic or Amino benzoic acid (usually
hydrolysed by pseudo cholinesterase)
 Examples: Benoxinate (Fluress); Butamben (Butesin)
 iii).Chloroprocaine (Nesacaine); v). Cocaine
 v).Cyclomethicaine (Surfacaine); vi). Dyclonine
(Dyclone); vii).Ethyl aminobenzoate (Benzocaine);
viii).Procaine (Novocaine); ix).Proparacaine (Aktaine)
 x).Tetracaine (Pontocaine
Classification of LAs
2. Amides: Largely metabolised in the liver
 Examples: Bupivacaine (Marcaine); ii).Dibucaine
(Nupercaine); iii).Etidocaine (Duranest); iv).Lidocaine
(Xylocaine)
 v).Mepivacaine (carbocaine); vi).Prilocaine (Citanest)
3. Ether-e.g. Pramoxine (Prax).
Classification of LAs
 Based on clinical usage:
 Topical e.g. benzocaine; butacaine
 Infiltration and block: e.g. procaine; lidocaine
 Spinal anesthetics: Procaine; lidocaine
 Epidural and caudal anesthetics: Lidocaine; prilocaine
Absorption of LAs
 Role of adrenaline
 Role of Hyaluronidase
Metabolism of LAs
 Esters of benzoic or Amino benzoic acid: mainly
metabolised by plasma cholinesterase(Pseudo
cholinesterase)
 Amides and Esters: Metabolised in the liver by:
esterases; amidases and conjugation reactions
Toxicity of LAS
 CNS toxicity
 Cardiovascular related toxicity
 Hypersensitivity reactions ( skin sensitization
following local application)
Brainy quote
 Nothing in this world can take the place of persistence.
Talent will not; nothing is more common than
unsuccessful people with talent. Genius will not;
unrewarded genius is almost a proverb. Education will
not; the world is full of educated failures. Persistence
and determination alone are omnipotent.( Calvin
Coolidge-1872-1933-U.S.President)