KETAMINE

KETAMINE :

• Introduced in 1965

Good Qualities :

1. Good analgesic
2. Weak anesthetic

• It produces disassociation dissociative anesthesia rather then generalized CNS depression.

• Eye remain open

• Slow nystagmus gauze > abnormal eye ball movement

• Corneal reflexes and light reflexes intact

• Exposure caritis 

PHYSICAL PROPERTIES:

• Clear liquid like water

• Water soluble / lipid soluble

• To maintain its isotonicity sodium chloride is added

• Benzatanium chloride as preservative

• Ph: 3.5-5 > acidic

AVAILABILITY:

• 10mg/ml

• 50mg/ml

• 100mg/ml

DOSE:

• Normal Adult: 2mg/kg

• Elder : 1-1.5mg/kg

• Children : 2-3mg/kg

• Infusion : 50 microgram / kg /mint

• 6-10mg/kg as IM 

• 4-8mg/kg as IM

• Onset of action : 30-60sec

• IM : 4-5 min

• Duration of action : IV : 15-25min

• Duration of action : IM : 25-30min

PHARMACOKINETIC:

ABSORBTION :

• Orally > IV > IM > Subcutaneous >Rectal > Nasally

DISTRIBUTION :

• Lipid soluble > 12% attached to plasma protein

• Acts on alpha and beta agonist causes increase CO , increase cardiac contractility , vasodilation in cerebral circulation

BIO TRANSFORMATION :

• Kidney

• Methylation

• Hyrdolation

• Active metabolites :Nor ketamine

• Inactive metabolites : Glucouronides

EXCRETION:

• 80% through renal

• 12% excreted unchanged 

MECHANISM OF ACTION :

A drug's mechanism of action is the way the drug works within the body to give the intended result. Ketamine's known mechanism of action involves being an antagonist for the NMDA receptors that are found in nerve cells. These receptors are involved in processing central nervous system input. Ketamine blocks this sensory input. This action is what accounts for most of the effects seen from ketamine.
There may be additional mechanisms of action as well, most of which remain a mystery. In addition to the NMDA receptors, ketamine has actions on other receptors within the body, such as opioid receptors, and has effects on sodium and calcium ion movement across cell membranes. Both of these actions may be related to its effectiveness for pain relief. It inhibits the re-uptake of serotonin, dopamine, and norepinephrine in the body, which may explain its antidepressant effects

PHARMACODYNAMICS:

EFFECT ON CNS:

• Analgesic property

• Partial sedation ( catalepsy)

• Induction smooth

• Recovery not smooth > emergence derilium

• Disorientation

• Nightmares or hallucinations

• Avoid verbal communication with patient during recovery

• Children and elderly patient have less hallucination 

• Vasodilation in cerebral circulation

• Increase CBF

• Incerase ICP

• Increase CMRO2

• Respiratory depression causes increase Co2

• Contraindicated in trauma & epileptic patient

EFFECT ON CVS:

• Agonist activity on alpha receptor causes vasodilation , increase BP upto 30% , increase HR by 20%,Tachycardia.

• Beta adrenegic effects are sympathetic activity , vasoconstriction ,bronchodilation ,increase cardiac contractility.

• Contraindicated in IHD , VHD 

• Can be used in CHF & Critical illness

EFFECT ON RESPIRATORY:

• Transient apnea may occur

• Ventilation are well maintained

• Pharyngeal and laryngeal are intact

• Relaxation in bronchial muscle

• Can be used in asthma

• Antagonist activity of muscuranic > increase bronchial secretion

EFFECT ON SKELETAL:

• Increase skeletal muscle tone

• Stiffness

EFFECT ON UTERUS & PLACENTA:

• It crosses placenta 

• Contraindicated in pregnancy

• Increase uterine muscle tone causes abortion

• Can be used in shock & hypovolumeia

EFFECT ON EYE:

• Increase IOP

• Contraindicated in open eye surgery & Penetrating eye surgery 

EFFECT ON GIT:

• Increase salivary secretion

• Increase gastric secretion

• Increase peristalsis

EFFECT ON LIVER:

• Increase production of liver enzymes

EFFECT ON RENAL :

• Increase GFR

SIDE EFFECTS:

• Tachycardia

• Emergence

• Hypertension

• Restlessness

• Agitaition

• Increase salivation

• Hallucination

• Increase ICP

• Increase IOP

• Increase bronchial secretion 

INDICATION:

• Induction

• Asthma

• CHF

• Shock

• Pre hospital anesthesia

• Used in developing countries

• Can be used without ventilation

CONTRAINDICATION:

• Epileptic

• Pregnancy

• Head injury

• Open eye injury

• Airway obstruction