Medication—A Formidable Defender - Pharmacology

Your natural defense against bacteria is a phagocytic response. Cells in your body engulf a pathogen, basically eat it and remove the injured tissue. Many times your body needs help from medication that can kill microbials. These are called antimicrobials. An antimicrobial is a medication that kills a microorganism. There are many types of antimicrobials. Each is designed to kill specific microorganisms. The most familiar is an antibiotic, which kills bacteria. Antibiotics kill microbialsthe good and the bad. For example, an antibiotic used to kill bacteria that causes a urinary tract infection will also kill the flora in your intestine that are used to help digest food.

Patients are also treated with medication that eases the symptoms of inflam-mation but doesn’t kill microbials. These are prostaglandin inhibitors.

Prostaglandins are chemical mediators that bring about the inflammatory response by vasodilatation, relaxing smooth muscle, making capillaries perme-able, and sensitizing nerve cells within the affected area to pain. A prostaglandin inhibitor reduces the production of prostaglandins and thereby reduces the symptoms of inflammation.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are aspirin and “aspirin-like drugs.” Aspirin is the most commonly used prostaglandin inhibitor because it is an analgesic to relieve pain. It is also an antipyretic to lower body temperature and it is an anticoagulant that inhibits the formation of platelets.

Other nonsteriodal anti-inflammatory drugs (NSAIDs) are also prostaglandin inhibitors. Other NSAIDs require a lower dose than aspirin to have the same analgesic effect. However, most NSAIDs have a lower anti-inflammatory effect than aspirin.


Two of the first antimicrobials developed were sulfonamides and penicillin (PCN). Sulfonamides are bacteriostatic, which means they stop the growth of bacteria, but do not kill bacteria. Penicillin, the first antibiotic, is a bacteriocidal and kills bacteria using lysis, which explodes the bacteria into parts.

Tip: A static means stops growth while cidal (homicide) means kills.

Today there are many synthetic and semi-synthetic antimicrobials on the market that stop some bacteria from growing and kill other bacteria. For example, chloramphenicol is bacteriostatic and stops most bacteria from growing while it is bacteriocidal and kills S pneumoniae and H influenza in cerebral spinal fluid. Tetracycline is also bacteriostatic and bacteriocidal; in small concentrations it stops the growth of bacteria and in high concentration it kills bacteria.

Sulfonamides and penicillin are administered orally, topically as an ointment or cream, or parenterally and are absorbed into the body and distributed by the circulatory system. In severe infections, they can be administered directly at the site of the infection such as in the eye or rubbed on the skin.

There are four ways in which these medications work.

  1. They inhibit the bacteria from growing a cell wall (cell wall synthesis).
  2. They disrupt or alter the permeability of the bacteria’s membrane. The membrane is within the cell wall and is used to let nutrients into the cell and send waste out of the cell.
  3. They inhibit the bacteria’s ability to make protein (protein synthesis). Medications that stop the growth of bacteria interrupt steps in protein synthesis. Those that kill bacteria cause the bacteria to form defective proteins.
  4. They inhibit the bacteria’s capability to make (synthesize) essential metabolites. A metabolite is a component necessary for bacteria’s metabolism to function properly.

Medication used to stop the growth of microbials or kill them outright have side effects, some of which can adversely affect the patient. Some cause an allergic reaction while others lead to an exaggerated immune response. Here are a few common ones that you probably recognize:

  • Rash
  • Fever
  • Urticaria (hives) with pruritis (itching)
  • Chills, general erythema (redness)
  • Anaphylaxis (circulatory collapse)

These side effects are usually treatable by using other medication such as:

  • Antihistamines (Benadryl)
  • Epinephrine (adrenalin)
  • Steroids for anti-inflammatory response

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