Saturday, March 2, 2013

Basic Knowledge about Pharmacology

What is pharmacology ?

Pharmacology is the science of studying the effect of drugs on living organisms.
Scientific study of the interactions between drugs and the body.

Two parts of pharmacology

1-  Pharmacokinetics:                  
 What the body does to drug
2-  Pharmacodynamics:                
 What the drug does to body

What is drug ?

A chemical substance that can modulate the current physiological status of a biological system.
A chemical which is utilized for the diagnosis, prevention and cure of an unwanted health condition (definition by FDA)

 Source of drugs

Ancient:Natural products

  • Plants 
  • Animals
  • Minerals
  • Active principles of natural products
  • Artificial synthetics: (I) Full synthetic (II) Semi synthetic (III) Biological engineering

From natural product to active principles

Differences between drug and poison
All the substances are poisons

There are no distinct borderline between them.
Any drug will be toxic once they are overdosed.
toxic dose; lethal dose

What pharmacology is not ?

This is a separate profession responsible for the
preparation and dispensation of medication.
Know as Pharmaceutical Science

Missions of pharmacology

Explore the pharmacokinetic and pharmacodynamic features  of  drugs
Probe the mystery of life process
Find and develop new drugs

What do we must know about drug ?

1-Drug action
2-Mechanism of action
3-Major adverse drug reaction
4-Clinically important pharmacokinetics
5-Clinical application

History of medicines:

Phase I: Superstition and Experience (Empiricism)
Phase II: Using natural products to treat diseases
Islamic physicians; e.g. Avicenna: Herbal medicine
China: Sheng Nong’s Herbal Classic (神农本草经), described 365 TCM; Compendium of Materia Medica  (本草纲目), described 1892 TCM
Greeks; e.g. Dioscorides: De materia medica, described 600 plants
Phase III: Scientific
Using pure drug compounds
Understanding physio-pathology of diseases and pharmacology of drugs

Modern pharmacology originated in Europe
1. Francois Magendie (1783-1855), a French physiologist, Experimental procedures with animals for determination of drug action.
2. Claude Bernard (1813-1878),investigated the plant extract curare and proposed a site of action for this agent.
3. Rudolph Buchheim (1820-1879). In 1847 established the first laboratory in the basement of his home in Dorpat which is the cradle of experimental pharmacology.
4. Oswald Schmiedeberg (1838-1921). In 1872 set up an institute of pharmacology in Strasbourg, which became a mecca for training in pharmacology
5. John J. Abel (1857-1938) established the first chair of pharmacology in the U.S.A. (U. Michigan, 1891) after training in Germany. He is known as "The Father of American Pharmacology".

Pharmacology in CSU
1945: First lecture on pharmacology lectured by 叶雨文教授 (Professor Ye Yuwen)(1916-2001)
1954:  Set up the Department of Pharmacology
2002: Established the College of Pharmacy and Institute of Clinical Pharmacology (college-level)
2001: National key disciplines
2004: State excellent courses

 Process of Drug Development

Idea-to-new medicine road - Full Development phase:
In this Full Development stage, known as Phase lll, several thousand patients with the particular disease receive the drug in carefully controlled studies to test its safety, tolerability, and efficacy. Finally, if the compound has proved its worth in all these tests, it enters the Registration phase in which the data of its entire history are compiled and analyzed in a regulatory submission. This New Drug Application, or NDA, is submitted to the FDA for review. In parallel, a Marketing Authorization Application (MAA) is filed in Europe, followed by a Japanese NDA. Only after a successful regulatory review does the candidate become a new medicine.

High Risk Process 

  High attrition
  • To turn out just one to two products requires about a hundred discovery projects or approaches, involving upwards of 7 million compound tests in early screening assays. This  level of screening produces about a thousand compounds with some of the criteria we are looking for. 
  • Follow-up molecular design and sophisticated biological testing narrows the number of development candidates.  
  • Once safety is confirmed in animal studies, compounds are advanced into human clinical trials where efficacy, safety and toleration are confirmed.
Clinical Trial: Evaluating Drugs in Humans
Phase I – small numbers; healthy adult volunteers
 Safety, Pharmacokinetics (PK), side effects

Phase II - small numbers; subjects with disease
 Efficacy, safety, PK, and side effects
 Randomized, Double-blind, placebo controlled

Phase III – large multicenter clinical trials
 Efficacy for specific indications
 Large sample of specific patients (300 or 1,000)
 Randomized double-blind placebo controlled

Phase IV – post SFDA/FDA approval
 Efficacy for specific indication
 Drug utilization patterns and additional efficacy
 Rare, severe side effects/toxicity

This is just a beginning stay tuned to know more about Pharmacology

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