Biology (Drugs)

• A drug is any substance taken into the body that modifies or affects chemical reactions in the body
• There are several types of drugs.

  Medicinal drugs include:

  1. Pain relievers. Eg: Aspirin, Paracetamol, Morphine, etc.
  2. Anti inflammatory drugs. Eg: Ibuprofen.
  3. Antihistamine. Eg: Celestamine.
  4. Antibiotics. Eg: Amoxicillin.
• Antibiotics are a group of drugs that destroy bacteria wall formation, inhibit protein synthesis and metabolism in the pathogen cell.
• Antibiotics cure bacterial diseases.
• They are administered either through injection, applied on the skin or through the mouth.
• Antibiotics cannot kill viruses since viruses don't have a cell wall, but rather live inside host cells, taking over their metabolic processes.
• Antibiotics either kill bacteria directly or stop them reproducing so that the body's defence systems can kill and destroy them.
• Doctors prescribe a course of antibiotics that have to be taken over a certain period of time.
• Antibiotic Resistance:

  Some bacteria are resistant to antibiotics which reduces their effectiveness.
• Penicillin was the first antibiotic to be discovered and mass produced.
• Penicillin acts on bacterial cell-walls by preventing their formation. This leads to breakdown of cell-walls and leakage of their cell contents.
• Many bacteria have become resistant to antibiotics as a a result of over-use, misuse and underuse. Hence mutation occurs in the bacterial population.
• Over-use of antibiotics has led to an increase in bacterial resistance.
• Over-use was responsible for development of methicillin-resistant staphylococcus aureus (MRSA).
• This caused death to patients with suppressed immune systems such as those who had organ transplants.
• Number of cases of MRSA in the UK and US hospitals have reduced as a result of specific strategies such as prescribing antibiotics when only absolutely necessary.
• When bacteria are exposed to an antibiotic such as penicillin, most are killed. However, some individual bacteria have a mutation giving resistance to the antibiotic. The bacteria may be able to produce an enzyme that breaks down the antibiotic. These individual bacteria survive to reproduce (through binary fission) and pass the gene for resistance to their offspring.
• An example of this is seen in MRSA- the strain of bacteria. Staphylococcus aureus is resistant to the antibiotic methicillin.