Classification of toxic actions of drugs

02Sep08

• Toxic action due to overdose

1. Too much drugs in body
2. 2 types
   1. Absolutely overdose – patient took big amount of doses
   2. Insufficiency of biotransformation system
      1. Not enough elimination of drug
      2. Accumulation of drug in body
      3. Resulting from kidney failure

1. Specific toxic actions of drug
   1. Is associated with
      1. Drug structure
      2. Mechanism of actions
      3. Effects

 

• Toxin action on route of administrations (input/output)

 

• Direct toxic action on different organs

 

• Addiction

1. Psychotic Addiction
2. Physical Addiction

 

• Tolerance

1. Pharmacological phenomenon associated with decreased effect of drug during administration
2. Mechanism of tolerance
   1. Decreased absorption of drug due to irritation & atrophy of membranes
      1. Example: skizophrenia _ chlonepramazine
   1. Activation of physiological system that produces opposite action
      1. Example: nitroglycerine –> vasodilation
      2. In physiological response, body produces more Renin –> Angiotensin (vasoconstrictor)
   1. Decreased sensitivity of receptors to drugs
      1. Example: morphine
      2. In case of addictions
   1. Activation of enzymes that causes degradation of drugs
      1. Example: barbiturates activate hepatic enzymes
   1. Antiinfective drug – increased resistance of microorganism
   2. Etiological drug – accommodation to drug

 

• Withdraw Syndrome

1. If patient stop using drug, the symptom appears again
2. Due to
   1. Dose of drug
   2. Strategy of discontinuing

1. Drug should be discontinued slowly
2. Administration of steroids

 

• Accumulation

1. Material accumulation
   1. Accumulation of drug molecules in the body
   2. Usually by lipophilic drug due to retention in fatty tissue

1. Physiological accumulation
   1. Drug is eliminated but the effect is accumulated
   2. Example: alcohol
   3. Associated with actions of drug in specific part of CNS

1. Allergic reactions of drug
   1. Associated with hyperactivity of immune system
   2. Resulting in allergic @ pseudoallergic reaction
   3. Reboud Reaction
      1. Associated with big dose @ fast injection during administration
      2. Example: injection of a therapeutic dosage of antihypertensive drug Clonastine rapidly causes antihypertensive crisis

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