Chapter 2: Review of Basic Principles of Pharmacology
Chapter 7: Cultural and Ethnic Influences in Pharmacotherapeutics
Chapter 8: An Introduction to Pharmacogenomics
Chapter 2: Review of Basic Principles of Pharmacology
How Drugs are Developed
Drugs are developed by pharmaceutical companies to help patients and to make money
The early part of the drug development process is called the preclinical stage
Pharmaceutical companies will identify a drug target, starting sometimes with ingredients
isolated from a plant (or organism in the case of antibiotics) with desirable medicinal
properties, sometimes with a molecular target identified in the body to produce the desired
response, and sometimes with a disease in need of treatment.
Many drugs are examined as pharmaceutical companies seek the elusive perfect drug
with just the right combination of properties. Preclinical studies are performed on cells,
isolated tissues and organs, and in laboratory animals to identify promising compounds
Drugs approved by the Food and Drug Administration (FDA) must be both safe and
effective and are screened by pharmacologists specializing in various aspects of drug
activity.
Ideally, drugs will produce their desired effects at dosages well below those needed to
produce toxicity.
During the clinical stage of new drug development, pharmaceutical companies must
establish the safety and effectiveness of new products in humans.
Phase I clinical trials typically establish biological effects as well as safe dosages
and pharmacokinetics in a small number of healthy patients.
o During phase II clinical trials, new drugs are used to treat disease in a small number
of patients and to establish the n potential of the drug to improve patient outcomes.
If the drug still looks promising, phase III clinical trials will compare the new medication
to standard therapy in a larger number of patients studied by at sites across the country.
New drugs must be at least as good as, and it is hoped better than, other available
therapies. Throughout the process, pharmaceutical companies work with the FDA.
After being approved by the FDA, drugs are continuously monitored through post-marketing
surveillance, in which health professionals are encouraged to report adverse events, which
are studied by both pharmaceutical companies and the FDA.
Drug Responses
Homeostasis is the tendency of a cell, tissue, or the body not to respond to drugs but instead
to maintain the internal environment by adjusting physiological processes.
Before a medication can produce a response, it often must overcome
homeostatic mechanisms.
Drug effects depend on the amount of drug that is administered.
o If the dose is below that needed to produce a measurable biological effect, then
no response is observed; any effects of the drug are not sufficient to overcome
homeostatic capabilities.
, o If an adequate dose is administered, there will be a measurable biological response.
With an even higher dose, we may see a greater response.
At some point, however, we will be unwilling to increase the dosage further, either because
we have already achieved a desired or maximum response or because we are concerned
about producing additional responses that might harm the patient.
Because pharmacology is the study of substances that produce biological
responses, measurement of what happens when we administer medications is
important.
Two types - these responses differ in how they are measured and dictate dosing decisions
to achieve the desired effect.