see also:

• local anaesthetic agents
• drug dependency
• Mx of psychostimulant toxicity from amphetamines and related substances
• intravenous drug users (IVDU) or injection drug use (IDU)

• 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;

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

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

• degraded by plasma esterases; T½ plasma 1hr;

• 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

• usually if > 6mg/kg

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

• decreased myocardial excitability, decreased conduction, decreased contractility;
• heart block or VF esp. if inadvertent i/vascular injection;
• AMI;