Chemicals In Medicines
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Chemicals in medicines
Rakesh Mohan Hallen
The words medicine and drug are often used in our country to mean the same substances: any substance, manufactured artificially, which can help recovery from sickness, relieve symptoms or modify a natural process in the body. A medicine is often a mixture of several chemical compounds. Even if it has only one active component compound often other substances are used as fillers or binders to give it bulk. Chemistry, the science related to chemical substances, provides us the tools to make and study the substances that are the constituents of almost all medicines. The past hundred years or so, ever since the advent of organic chemistry, many chemical compounds have been discovered in nature that are effective for curing diseases. Modern chemistry has also made it possible to synthesize several medicines using methods of organic chemistry.
The most common medicines can be classified into few groups, e.g. antibiotics; antiseptics; analgesics; and antipyretics etc. While an antibiotic is a drug that kills or prevents the growth of bacteria, an analgesic is often used to relieve pain.
There are very many medicines that come under each of these groups. Often several chemical compounds that make a particular group of medicines, say antibiotics have similar chemical structure. Since the medicines in a particular group are effective for treating a particular type of ailment or disease, their mode of action can also be very similar. But, the methods used to isolate a medicine from its natural sources or to synthesize it are most often very different.
In this article, I have tried to find out the relationships between chemical structures of medicines in three groups of medicines, viz. Antibiotics; Antipyretics and Analgesics. I have also explored the mode of action of these groups of medicines and the chemical methods used to make them available.
Antibiotics
Our body and our domestic animals, can serve as hosts to a wide variety of disease-causing organisms (pathogens): These are:
bacteria
viruses
fungi
protozoons
Here we will examine only those chemicals that are used to combat bacterial pathogens An antibiotic (Greek anti, “against”; bios, “life”), is a chemical substance produced by one organism that is destructive to another. This process traditionally has been called antibiosis and is the opposite of symbiosis. More specifically, an antibiotic is a type of chemotherapeutic agent that has a toxic effect on certain types of disease-producing microorganisms without acting dangerously on the patient. The definition most used for antibiotics is: any substance produced by a microorganism which harms or kills another microorganism. However, antibiotics DO NOT harm viruses. Doctors often prescribe antibiotics when you may have a viral infection because of the possibility that you may also acquire a bacterial infection because you are so ill with a virus – being ill places a person at risk for certain bacterial infections that are normally handled without any problem.
The overwhelming majority of antibiotic substances are natural products that certain bacteria and fungi (molds) produce and send outside of their cells. About 90% of the antibiotics in use today, are isolated from bacteria. There are a few antibiotics, however, which are completely synthetic that is, are made from scratch in the laboratory. These particular antibiotics are designed to inhibit some process previously identified to be completely unique to bacteria, and necessary for the bacterium to remain alive. An antibiotic can be most often classified into any one of the following categories of chemical compound:
Aminoglycosides
Glycopeptides
Beta Lactams also known as Penicillins
Tetracycline
Quinolines
Sulfonamides
Aminoglycosides
Aminoglycosides are antibiotics that are often administered into veins or muscle to treat serious bacterial infections. Some aminoglycosides are also used orally to treat intestinal infections or topically to treat eye infections. Some very popular examples of this group of antibiotics are:
Examples are:
Streptomycin
Kanamycin
Neomycin
Gentamycin
Glycopeptides
Glycopeptide antibiotics are a class of antibiotic drugs. They consist of a glycosylated cyclic or polycyclic nonribosomal peptide. Important glycopeptide antibiotics include vancomycin, teicoplanin, ramoplanin, and decaplanin.
This class of drugs inhibit the synthesis of cell walls in susceptible microbes by inhibiting peptidoglycan synthesis. Due to their toxicity, their use is restricted to those patients who are critically ill or who have a demonstrated hypersensitivity to the β-lactams.
Penicillins are one major class of antibiotics. They are used to treat strep throat and countless other infections. Examples of various kinds of penicillins include
Amoxicillin
Ampicillin
Azlocillin
Carbenicillin
Cloxacillin
Dicloxacillin
Flucloxacillin
Mezlocillin
Nafcillin
Penicillin
Common structural features of Beta-Lactams; (The beta-lactams get their name from the characteristic ring structure — shown here in blue — that they all share. (The green arrow shows the bond that is broken by a class of enzymes called beta-lactamases that are synthesized by many penicillin-resistant bacteria.)
Tetracycline
Tetracyclines are another category of antibiotics. In addition to being used to treat infections, they are often used to manage acne. A few of the tetracyclines frequently