Class 12 Chemistry Chemistry In Everyday Life Neurologically Active Drugs

Neurologically Active Drugs

  • Tranquilizers and analgesics are neurologically active drugs. These affect the message transfer mechanism from nerve to receptor.
  • Tranquilizers
  • Tranquilizers are a class of chemical compounds used for the treatment of stress, and mild or even severe mental diseases.
  • These relieve anxiety, stress, irritability or excitement by inducing a sense of well-being. They form an essential component of sleeping pills.
  • There are various types of tranquilizers.
  • They function by different mechanisms.
  • For example, noradrenaline is one of the neurotransmitters that play a role in mood changes.
  • If the level of noradrenaline is low for some reason, then the signal-sending activity becomes low, and the person suffers from depression.
  • In such situations, antidepressant drugs are required.
  • These drugs inhibit the enzymes which catalyse the degradation of noradrenaline.


  • If the enzyme is inhibited, this important neurotransmitter is slowly metabolised and can activate its receptor for longer periods of time, thus counteracting the effect of depression.
  • Iproniazid and phenelzine are two such drugs.
  • Some tranquilizers namely, chlordiazepoxide and meprobamate, are relatively mild tranquilizers suitable for relieving tension.
  • Equanil is used in controlling depression and hypertension.


  • Some important class of tranquilizers are as :
    • Derivatives of barbituric acid viz., veronal, amytal, nembutal, luminal and seconal.
    • These derivatives are called barbiturates. Barbiturates are hypnotic, i.e., sleep producing agents. Some other substances used as tranquilizers are valium and serotonin.


  • Analgesics
  • Analgesics reduce or finish the pain without causing impairment of consciousness, mental confusion, incoordination or paralysis or some other disturbances of nervous system.
  • These are classified as follows:

(i) Non-narcotic (non-addictive) analgesics

(ii) Narcotic drugs


  • Non-narcotic (non-addictive) analgesics
  • Aspirin and paracetamol belong to the class of non-narcotic analgesics.
  • Aspirin is the most common example. It inhibits the synthesis of chemicals known as prostaglandins which stimulate inflammation in the tissue and cause pain.
  • These drugs are effective in relieving skeletal pain such as that due to arthritis. These drugs have many other effects such as reducing fever (antipyretic). and preventing platelet coagulation.
  • They prevent platelet coagulation because of this anti-blood clotting action; aspirin finds use in prevention of heart attacks.
  • Aspirin is toxic for liver and sometimes causes bleeding from stomach. So naproxen, ibuprofen, paracetamol are widely used analgesics.


  • Narcotic Analgesics
  • Morphine and many of its homologues, when administered in medicinal doses, relieve pain and produce sleep.
  • In poisonous doses, these produce stupor, coma, convulsions and ultimately death.
  • Morphine narcotics are sometimes referred to as opiates, since they are obtained from the opium poppy.
  • These analgesics are chiefly used for the relief of postoperative pain, cardiac pain and pains of terminal cancer, and in child birth.


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