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cocaine

cocaine

history

  • the 1st LA discovered, pure alkaloid isolated 1860 from leaves of Erythroxylon coca a bush in Andes growing @ 1000-3000m altitude;
  • studied as LA, Mx of morphine withdrawal, spinal anaesthetic from 1884;
  • used as LA eye but ceased as caused corneal ulcers;

pharmacology

  • Absorption: rapidly absorbed from mucosa & s/c esp. if inflammation;

action

  • prevents generation & conduction of nerve impulses by blockade of voltage-gated Na channel;
  • potentiates noradrenergic systems as inhibits NA uptake;

metabolism & excretion

  • degraded by plasma esterases; T½ plasma 1hr;

adverse effects of cocaine

  • euphoria/dysphoria → garrulousness & excitement → tremors
  • vomiting (effect on vomiting centre)
  • bradycardia (central vagal stimulation) → tachycardia (central & periph. effect)
    • → vasoconstriction (increased sympathetic stimulation) → hypertension → hypotension
  • cocaine fever
  • tolerance, dependence

toxic effects

  • usually if > 6mg/kg

CNS:

  • initial seizures (effect of inhib.neurons)
  • subsequent coma, resp. arrest (all neurons affected)

CVS:

  • decreased myocardial excitability, decreased conduction, decreased contractility;
  • heart block or VF esp. if inadvertent i/vascular injection;
  • AMI;
cocaine.txt · Last modified: 2011/05/16 15:38 (external edit)