In this module, we will watch three videos. The first introduces fields relating to how drugs act on the body, including pharmacology and pharmacokinetics. The second introduces computational and mathematical networks. The third will take a look at one way these come together, including the emerging field of network medicine. The learning tasks will be given at the end.

Video 1: Pharmacology

Some General Definitions
A .Pharmacology studies the effects of drugs and how they exert their effects.
B. Drugs are chemicals that act on living systems at the chemical (molecular) level.
C. Medical pharmacology is the study of drugs used for the diagnosis, prevention, and treatment of disease.
D. Toxicology is the study of the untoward effects of chemical agents on living systems. It is usually considered an area of pharmacology.
E. Pharmacodynamic properties of a drug describe the action of the drug on the body, including receptor interactions, dose-response phenomena, and mechanisms of therapeutic and toxic action.
F. Pharmacokinetic properties describe the action of the body on the drug, including absorption, distribution, metabolism, and excretion. Elimination of a drug may be achieved by metabolism or by excretion.
G. Efficacy is maximum effect that a drug can produce, regardless of dose.

H. Potency is a measure of drug activity expressed in terms of the amount required to produce an effect of given intensity.
I. Volume of distribution (Vd) relates amount of drug in body to plasma concentration [Vd = (amount of drug in the body) / (plasma drug concentration) ]
J. Bioavailability is fraction of administered dose that reaches systemic circulation.

Introduction to Pharmacokinetics
Pharmacokinetics concerns the effects of the body on the administered drug. It can be viewed as the processes of absorption, distribution, and elimination. Elimination studies includes both metabolism and excretion. All of these processes involve movement of drug molecules through various body compartments and across the cell membrane barriers , cell contents and so forth.

A. Absorption of Drugs: The rate and efficiency of absorption differs depending on the route of administration. Common routes of administration of drugs and some of their features include oral,sublingual,rectal,intramuscular,subcutaneous,Inhalation,topical,transdermal and intravenous.

B. Distribution of Drugs. The distribution of drugs from the site of absorption, through the bloodstream and to the target tissue depends upon blood flow,solubility, binding and ability to cross special barriers.

C. Elimination of Drugs:
The rate of elimination (disappearance of active drug molecules from the bloodstream or body) is almost always related to termination of pharmacodynamic effect. Two major routes of elimination is excretion and metabolism.

Video 2: Networks

Video 3: Network medicine
This lecture is by physicist Albert-László Barabási who describes the emerging field of network medicine. As we described at the start of this course, drug discovery and medicine is going through a transformative phase where we are understanding that disease and the treatment of disease is complex, involving system wide impact on the body. We are thus seeing computational and data science paradigms that reflect this. Numerous terms are used, including network biology, network medicine, systems biology, and systems chemical biology.

1 . Pharmacology (Page 58 - 64) (must read)

Learning Tasks
1. Read Albert-László's Nature article on Network Medicine

Going Deeper
2. Ravi Iyengar Systems Pharmacology
3. Network Pharmacology : The Next Paradigm in Drug Discovery
4. Coursera Courses on Network analysis in Systems Biology