Application of chemical reactions to drug use

The intake of a drug must be at a sufficient concentration that it has a therapeutic effect at the site needed, but not so high as to cause toxicity. Too little can be ineffective. The above factors all interact into a study called pharmacokinetics , which concentrates mainly on the four major factors  

These four factors are quantitatively studied to find the best way to administer the drug. Any drug administration should therefore be tailor-made for a particular person and the severity of the situation. For common colds and the like this is not usually required but for the more invasive cancer drugs this is crucial. Overdoses can have serious consequences. Similarly, miscalculation of radiation treatments can be catastrophic for the patient. The analysis by the pathology laboratories of periodic samples of excretion products can give a good indication of the metabolic break-up of the drug and its retention at the crucial sites. 

Chemists studying the pathways, retention and metabolism of a drug often use animals to test the models for their modes of action before trying it out on humans. There is always a safety factor built into any human trial model as drug mechanisms and the human body are such complex systems. The models are expressed in 

This method introduces the drug by injection or infusion and bypasses the absorption factor as the drug is often placed directly at the site needed. This method can accurately maintain the correct concentration of the drug in the plasma, blood or tissues. 

It needs initial heat to overcome activation energy to start the reaction (1) 

---