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 lifeNot 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

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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/AnesthesiaThe 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 topicIf 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 anestheticsWhat 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 GAsHow are they classified?Examples in various classes-Commonly used anesthetics in various

classes-

Local anaestheticsLocal 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 LAsBased 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). Cocainev).Cyclomethicaine (Surfacaine); vi). Dyclonine

(Dyclone); vii).Ethyl aminobenzoate (Benzocaine); viii).Procaine (Novocaine); ix).Proparacaine (Aktaine)

x).Tetracaine (Pontocaine

Classification of LAs2. Amides: Largely metabolised in the liverExamples: 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 LAsBased on clinical usage: Topical e.g. benzocaine; butacaineInfiltration and block: e.g. procaine; lidocaineSpinal anesthetics: Procaine; lidocaineEpidural and caudal anesthetics: Lidocaine;

prilocaine

Absorption of LAsRole of adrenalineRole of Hyaluronidase

Metabolism of LAsEsters 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 LASCNS toxicityCardiovascular related toxicityHypersensitivity reactions ( skin sensitization

following local application)

Brainy quoteNothing 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)