by Ethan Pilot

Medicines and Drugs


Overview

Medicine and Drug are often used as interchangeable terms, but have different meanings.
Marijuana is a drug, and some argue, a medicine
Marijuana is a drug, and some argue, a medicine
A drug is a chemical that affects how the body works while a medicine is a substance that improves health, usually by assisting the body in its natural healing processes. The term drug is also sometimes associated with illegal substances such as cocaine or heroin but its usage is not limited to these types of substances. A drug's effects can be changes for better or worse, such as altering of mood, emotion, sensory perception, level (or lack) or consciousness, or the general physiological state of a person. but medicines will only contain beneficial drugs. The positive effects of a medicine are it's therapeutic effects.

Types of Medicines

The body's internal chemistry is very intricate, meaning that when a foreign substance such as a drug is introduced, there will be more than one effect on the body, causing drugs to be difficult to classify precisely. The main sections IB focuses on are as follows:
  • supplements to the body's natural defense mechanisms such as antibacterials and antivirals
  • drugs that affect metabolic processes such as antacids
  • brain and nervous-system targeting drugs that can change perceptions such as analgesics, stimulants, depressants, and other mind-altering drugs such as hallucinogens.
  • drugs that work through the power of suggestion, known as placebos. Although these are not really by definition drugs, as they are of no chemical medicinal value, patients believe they are taking medicine, causing their brain to produce opioids, natural pain-relieving compounds.

Drug Administration


Methods

The method of delivery varies from drug to drug. Sometimes certain methods allow the drug to act faster or to more effectively target a specific area in the body. Other times, certain methods cannot be used due to their adverse effect on the drug, such as how untreated penicillin will break down in the stomach, so it cannot be taken orally unless it is treated to resist this.
A skin patch that administers nicotine with minimal effort and discomfort to the user
A skin patch that administers nicotine with minimal effort and discomfort to the user

Type
Description
Examples
oral
taken by mouth
pills, liquids
inhalation
vapor/smoke breathed in
inhalers, cigarettes
skin patch
chemicals absorb into bloodstream through skin
hormone therapy, nicotine patches
suppository
inserted into rectum
hemorrhoid or digestive illness treatment
eye/ear drop
liquids dropped directly into the eye or ear
eye and ear infection treatment
Intramuscular injection
injected into a muscle with a needle
vaccines and some antibiotics such as penicillin
intravenous injection
injected directly into the bloodstream with a needle;
this is the fastest method of injection
local anesthetics, heroin
subcutaneous injection
injected directly under the surface skin
into subcutaneous tissue
dental injections, insulin
At first one doughnut is pretty satisfying, but eventually you become jaded to the doughnut's flavor, so you eat two instead of one.  However, the fatty side effects of the doughnuts are still the same, increasing the risk of becoming obese, even if the threshold of their deliciousness is now higher for you.  The concept of tolerance is similar to this idea.
At first one doughnut is pretty satisfying, but eventually you become jaded to the doughnut's flavor, so you eat two instead of one. However, the fatty side effects of the doughnuts are still the same, increasing the risk of becoming obese, even if the threshold of their deliciousness is now higher for you. The concept of tolerance is similar to this idea.

Dosage and its Effects

Besides the method in which a drug is administered, the other factor that can affect how it functions is dosage. To make matters more difficult, the correct dosage changes depending on one's gender, age, and weight. diet, and environment. In an ideal situation, the amount of drug in the patient's bloodstream would be the same at all times; unfortunately, this is not possible without the use of an IV drip, which is not practical for everyday uses. Instead, the concentration of the drug in the bloodstream is kept between the therapeutic level, the lowest level which produces a non-negligible effects and the, and the toxic level. This range is known as the therapeutic window.
Over the course of a drug regimen, the body will often begin to adapt to the drug, raising the therapeutic level. However, the toxic does not increase, meaning that the therapeutic window decreases in size and risk of dependence and overdose increases. This process is known as tolerance. Another danger of tolerance is that the side effects may become exacerbated as the dosage increases. The side effects are all effects of a drug that are unintended, both good and bad. In the example of aspirin, it has both good side effects (such as reducing blood clots) but also bad side effects (stomach irritation). The degree to which side effects are acceptable depends on the nature of the disease the drug is treating; for example, it is more acceptable to have larger side effects on a medicine that treats a lethal disease than on a cold medicine.

Pharmaceutical Research, Development, and Testing


The process of creating a new drug and bringing it to market is very long and expensive one, often taking more than 10 years from start of development to release. The overall attrition rate is very high; thousands of candidate drugs are rejected for every new drug to reach the market. The stages are as follows:

Discovery Research

The first part of research is the identification and isolation of lead compounds, chemicals that have shown biological activity. These chemicals which are usually derived from plants or animals but also sometimes synthesized often will only be slightly reactive or have rather negative side effects. One example of what would be classified as a lead compound today is salicylic acid, the precursor to aspirin. Although this compound relieved pain, it also has a disgusting flavor and often caused vomiting. From these lead compounds, such as salicylic acid, more refined medicines, such as aspirin, are derived. These final medicines are reached from the analogues by making compounds related to the lead compound called analogues. These compounds are tested to determine which has the least side effects and the most optimal reactivity. The compound is then tested on animals determine the lethal does and the effective dose before human trials begin.

Development Research

The next component involves 3 levels of human testing to ensure the effectiveness of the drug. At first in phase 1, the drug is tested on 50-100 healthy volunteers to see how the drug reacts. After passing this level, it continues to phase II which now includes the treatment of 200-400 patients. If these patients show enough of an improvement, the drug continues to the final part, phase III, where out of a group of thousands of patients, half are given the drug and the other are given a placebo in a double blind test. After showing a significant improvement against the placebo at this level of testing, the drug is ready to move on to the next component of it's journey to the market.

Regulatory Review and Post-Marketing Monitoring

A thalidomide baby with no arms
A thalidomide baby with no arms
The final obstacle to a drug entering the market is regulatory review that comes with an application by a company to bring a new drug to market. In the United States, the regulatory review is carried out by the Food and Drug Administration (FDA). After the drug has reached the market, research continues to determine if the drug is having unintended long term side effects or if it is adversely affecting a susceptible group such as children or pregnant women. An example of the aftermarket review process in action is the Thalidomide case. In this incident, the drug was not tested on pregnant women in its original trials as it was marked initially only as an anti-inflammatory. However, after it was marketed to pregnant women as a treatment for morning sickness, it was discovered that it caused many serious, sometimes fatal, birth defects. After these problems were brought to light, the drug was pulled from the market, showing the importance of post-marketing monitoring.

Notes


1st image is from http://static.howstuffworks.com/gif/marijuana-leaf.jpg
2nd image is from http://indopain.com/images/stk63368cor-patch.jpg
3rd image is from http://2.bp.blogspot.com/_09jZJ5Gk438/STF2amNopOI/AAAAAAAAC9k/2u0OsiL_dXs/s320/Image059.jpg
4th image is from http://cdn.crooksandliars.com/files/uploads/2009/06/c-5_9ca82_0.jpg

References


http://www.medtrng.com/blackboard/medication_administration.htm
Pearson Baccalaureate Higher Level Chemistry
IB Chemistry Study Guide by Geoffrey Neuss
Chemistry, 3rd Edition by John Green and Sadru Damji