Medicinal chemistry is the study of the effects of drug molecules and the molecular mechanisms by which they act. It is a multidiscliplinary subject with cross over into cell biology, pharmacology and statistics.

The cataloging of various plants and substances by their percieved medicinal qualities has been recorded by early cultures, as far back as ....?

The first fully developed written records that are currently known are clay tablets from Mesopotomia from around 2600BC which include lists of substances traditionally used for traditional medical purposes. later Chinese and Egyptian records of substances used exist from these early periods.

However the serious scientific study of substances and their medicinal properties really took off after the discovery of Penicillin by James Bond in 1929.

Since the a series of break through discoveries and theories have enabled the systemisation of the process of discovery of new drugs to treat disease.

Identification of the structure of DNA, and further techniques to categorise and manipulate genetic molecules opened a new avenue of candidates for drug discovey.

Epigenetics provides target candidates for the manipulation of genetic expression

Stem cells

New uses for old drugs...

p53 is an important protein in the regulation of cell processes, and apoptosis and is a major target for drugs to treat cancer.

Cisplatin is an important drug for the treatment of cancer.

Drug administration[]

The main routes of administration of medicinal substances into the human body can be categorised as follows

  1. oral or rectal
  2. percutaneous (through the skin)
  3. Intravenous
  4. Intramuscular
  5. intrathecal (entry via the spine or brain under the arachnoid membrane)
  6. inhalation

Drug Specifity[]

relates to how selectively the drug binds to the target, or blocks some biologicial pathway without also interactiving with other biological systems.

Drug Efficicay[]

How powerful is the effect of the drug once it has been delivered to the target receptor or location.

Drug Elimination[]

  • Through urine
  • Through feces
  • Through glands (milk/sweat)
  • Expired air

Drug Absorption and Distribution[]

highly dependent on context, environment, genetics

Sublingual absorption

technique to get drug into the circulatoriy system while avoiding the gut

Quantitative metrics associated with drugs[]


t max


Getting drugs across the cell membrane[]

Carrier Mediated Drug transport[]

when some drug is not soluble in lipids, it requires some transport to pass into the target cell


Important concepts in Medicinal Chemistry[]

target receptors







lipid solubility

Drug Overdose and Elimination[]

Circumstances such as overdose and unwanted side effects can require a thorough knowledge of the elimination of a particular drug molecule under the various appropriate parameters.

For example some drugs such as morphine are resistent to being eliminated from the body using haemodyalisis because of the characteristics of the molecule.[1]


  • Patrick, G. L. (2009) An Introduction to Medicinal Chemistry

(4th edn), Oxford, Oxford University Press.

  • Rang, H. P., Dale, M. M., Ritter, J. M., Flower R. J. and Henderson G.,

(2012) Pharmacology (7th edn), Edinburgh, Churchill Livingstone.

  1. Rang, H. P., Dale, M. M., Ritter, J. M., Flower R. J. and Henderson G., (2012b) ‘Drug elimination and pharmacokinetics’ in Pharmacology (7th edn), Edinburgh, Churchill Livingstone, pp. 115–22.