Drugs- Types, action


Drugs are 4 types:

1. Depressants:

Depress brain activity. They include
  • Sedatives: Give calmness and relaxation. High doses induce sleep. E.g. Barbiturates (sleeping pills).
  • Tranquilizers: Lower tension and anxiety without inducing sleep. E.g. Benzodiazephines (e.g. Valium).
2. Opiate narcotics (pain killers):

- Drugs which bind to specific opioid receptors in CNS and gastrointestinal tract.

- They are analgesic & depressant (lower tension, anxiety, B.P and respiration rate and reduce visual activity).

- E.g. Opium and its derivatives (Opiates or Opioids).
- Opium is obtained from dried latex of unripe capsules of Poppy plant (Papavar somniferum).

Opium derivatives:
  • Morphine: Strong analgesic and sedative extracted from the latex of poppy plant. Useful during surgery.
  • Brown sugar
  • Heroin (Diacetyl morphine/smack): Most dangerous, white, odourless, bitter crystalline compound produced by acetylation of morphine. It is a depressant and slows down body functions. It is taken by snorting & injection.
  • Codeine: Mild analgesic. Used in cough syrups.

3. Stimulants:

- Stimulates CNS.

- E.g. Cocaine, Caffeine (cardiac stimulant), amphetamines (synthetic. Used in pep pills).

- Amphetamines & anabolic steroids are misused by some athletes.

- Coca alkaloid (Cocaine or coke/crack):
  • Obtained from coca plant (Erythroxylum coca)
  • Interferes the transport of neurotransmitter dopamine.
  • Cocaine is usually snorted.
  • Stimulate CNS producing euphoria and energy.
  • Excessive dosage causes hallucination.
4. Hallucinogens:

Atropa belladona
- They cause colourful hallucinations, change thoughts, feelings and perceptions.

- E.g. Mescaline, Psilocybin, Cannabinoids & LSD (Lysergic Acid diethylamide).

- Atropa belladonna & Datura are plants with hallucinogenic property.

  • Drugs that interact with cannabinoid receptors in brain.
  • Generally taken by inhalation and oral ingestion.
  • Natural cannabinoids are obtained from Cannabis sativa (Hemp plant). Its flower tops, leaves & resin are used to produce bhang, ganja, charas (hashish), marijuana etc.
  • Affects cardiovascular system.
Skeletal structure of cannabinoid molecule

Addiction and Dependence

  • Addiction: It is a psychological attachment (euphoria and a temporary feeling of well being) with drugs and alcohol. With repeated use of drugs, the tolerance level of the receptors increases. Thus the receptors respond only to higher doses leading to greater intake and addiction.
  • Dependence: It is the tendency of the body to manifest a characteristic and unpleasant withdrawal syndrome if regular dose of drugs/alcohol is abruptly discontinued. This results in anxiety, shakiness, nausea and sweating. Dependence leads to social adjustment problems.

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