Therapeutic Action of Different Classes of Drugs

Therapeutic Action of Different Classes of Drugs

Table of Content

Define Drugs

Define Drugs
Drugs are chemicals of low molecular mass which interacts with targets and bring about the response. When drugs are used for therapeutic purpose, it is known as medicine. Medicines are used in diagnosis, prevention, and treatment of diseases. Some drugs are also used as poisons to target cancer cells, this is known as chemotherapy.

Drugs are classified based on mode of action, mechanism of action, therapeutic effect etc.


What is a therapeutic effect of a drug?

The effect of any drug on any medical problem is known as therapeutic effect of a drug. It is mostly beneficial but it can be expected or unexpected.

Classification of drugs based on their therapeutic effect or therapeutic agent and their uses-

Analgesic

  • They are commonly known as pain killers.
  • They act on peripheral and central nervous system.
  • They are used to relief pain in conditions such as muscle sprains, overuse injuries etc.
  • Paracetamol is one of the common analgesic used by common people. It is used to treat pain and fever. It is also used to treat cancer pain after surgery.
  • Non-steroidal anti-inflammatory drugs also belong to analgesics. These drugs have anti-inflammatory, pain-killing and fever killing effect.

Structure of paracetamol

Fig. 1. Structure of paracetamol

Antacids

  • Overproduction of hydrochloric acid in stomach is known as acidity.
  • Acidity causes irritation and pain in the stomach.
  • Earlier sodium hydrogen carbonate is used to treat the acidity.
  • Metal hydroxides are better alternative for treating the acidity.
  • Hyperacidity also causes ulcer in the stomach.
  • Studies have shown that secretion of hydrochloric acid is promoted due to the secretion of histamine. The drug cimetidine is used to suppress the release of histamine. This decreases the secretion of histamine.

Antihistamines

  • These drugs are suppressor of histamines.
  • Drugs such as brompheniramine (Dimetapp) and terfenadine (Seldane), act as antihistamines. These drugs compete with receptors where histamine binds.

Structure of brompheniramine 

Fig. 2. Structure of brompheniramine

Antibiotic

  • They are used to target the bacterial infections.
  • They kill or inhibit the growth of the bacteria.
  • They are ineffective towards viruses.
  • There are two types of antibiotics- broad spectrum antibiotics that target the diverse bacterial infection. But some are narrow spectrum antibiotic, that targets only small number of bacterial infections.
  • The most common route for administration of antibiotic is oral.
  • The overdose of antibiotic makes bacteria resistant to the particular antibiotic.
  • Antibiotics can be bacteriostatic or bactericidal. Those that kill the bacteria are known as bactericidal such as vancomycin, whereas those inhibiting the growth of the bacteria are known as bacteriostatic. For example, tetracycline, sulphonamides.

Types of antibiotic Fig. 3. Types of antibiotic

Tranquilizers

  • They are classified as neurologically active drugs.
  • They are used to treat mild to severe mental illness.
  • They help in relief from anxiety, stress, irritability etc.
  • They are consumed as sleeping pills.
  • Noradrenaline is a hormone involved in mood changes. If the level of this hormone is low, people will suffer from depression. To relieve depression, anti-depressants are advisable.
  • They inhibit the enzymes that break down noradrenaline. Thus, maintains the level of this hormone.
  • Some tranquilizers such as chlordiazepoxide and meprobamate, are relatively mild tranquilizers suitable for relieving tension.  Equanil is used in controlling depression and hypertension

Structure of chlorodiazepoxide Fig. 4. Structure of chlorodiazepoxide

Stimulants

  • They are drugs that are used to accelerate the activity of the central nervous system. They make us feel more energetic, alert as well as focused. Such as cocaine amphetamine etc. 
  • They belong to class of neurologically active drugs.

 Structure of chlorodiazepoxide

Fig. 5. amphetamine

Antiseptics and Disinfectants

  • Antiseptics are chemicals used to kill the microorganisms on living tissues. They are applied on skin with a cut or wound. Examples are furacine, soframicine, etc. These are not ingested like antibiotics.

Structure of soframycin 

Fig. 6. Structure of soframycin

  • Dettol is also a very common antiseptic used from long time. It is composed of a mixture of chloroxylenol and terpineol.
  • Disinfectants are chemicals used to kill microorganisms on non-living things such as on floor, drainage system etc.
  • 0.2 per cent solution of phenol is an antiseptic while its one percent solution is disinfectant.

Antipyretic Drugs

  • These drugs are consumed to reduce the fever or body temperature.
  • Aspirin and paracetamol are the most common antipyretic that are used by common people.
  • These drugs act on prostaglandin induced increase in temperature.

Anti-fertility Drugs

  • They target the increasing population.
  • Increased population had raised many issues such as food scarcity, environment issues which lead to the consumption of antifertility drugs.
  • They are better known as birth control pills.
  • These pills contain estrogen, progesterone, or combination of both.
  • Norethindrone is an example of synthetic progesterone derivative most widely used as antifertility drug. The estrogen derivative which is used in combination with progesterone derivative is ethynylestradiol (novestrol).

Frequently Asked Questions(FAQs)


Q1: What is the action of a drug?

Answer: The action of a drug on human body is known as pharmacodynamics and how body reacts to the drug is known as pharmacokinetics.

Q2: What is a site of action of a drug?

Anwser: Different drugs have different site of action. Some bonds to receptors on the membrane and some acts inside the cell.

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Therapeutic Action of Different Classes of Drugs

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