This chapter covers the material covered in Option Module D: Medicinal Chemistry.

CORE

SPREAD 1: Pharmaceutical products and drug action

In animal studies, the therapeutic index is the lethal dose of a drug for 50% of the population (LD50) divided by the minimum effective dose for 50% of the population (ED50).

In humans, the therapeutic index is the toxic dose of a drug for 50% of the population (TD50) divided by the minimum effective dose for 50% of the population (ED50).

The therapeutic window is the range of dosages between the minimum amounts of the drug that produce the desired effect and a medically unacceptable adverse effect.

Dosage, tolerance, addiction and side effects are considerations of drug administration.

Bioavailability is the fraction of the administered dosage that reaches the target part of the human body.

The main steps in the development of synthetic drugs include identifying the need and structure, synthesis, yield and extraction.

Drug–receptor interactions are based on the structure of the drug and the site of activity.

Basics: What is a drug or medicine?

These are chemicals that have a known biological effect on humans or other animals. In the positive sense drugs and medicines are substances that can cure, prevent or help diagnose disease, or enhance physical well-being. Drugs of course can be misused for recreational purposes, especially hallucinogens.

All drugs have side-effects, an effect the drug has on the body that is secondary to the one intended. These can have adverse effects, or can be beneficial. Sometimes side-effects are of great concern, some will be minor. The seriousness of the disease the drug is being used for will affect the amount of side-effects tolerated in the drug.

Methods of administering drugs

It is important that drugs get into the blood stream as quickly as possible in order for them to reach the site where their effects will be needed. This can be via the stomach, lungs or directly into the bloodstream.

There are five common ways in which drugs can be administered.