How do medicine / drugs get delivered to the place where they're needed? Or do they just get dispersed throughout the body?
user
Pharmacology is the scientific field that studies how the body reacts to medicines and how medicines affect the body. Scientists funded by the National Institutes of Health are interested in many aspects of pharmacology, including one called pharmacokinetics, which deals with understanding the entire cycle of a medicine's life inside the body. Knowing more about each of the four main stages of pharmacokinetics, collectively referred to as ADME, aids the design of medicines that are more effective and that produce fewer side effects.

The first stage of ADME is A, for absorption. Medicines are absorbed when they travel from the site of administration into the body's circulation. A few of the most common ways to administer drugs are oral (such as swallowing an aspirin tablet), intramuscular (getting a flu shot in an arm muscle), subcutaneous (injecting insulin just under the skin), intravenous (receiving chemotherapy through a vein) or transdermal (wearing a skin patch). Medicines taken by mouth are shuttled via a special blood vessel leading from the digestive tract to the liver, where a large amount of the medicine is broken down. Other routes of drug administration bypass the liver, entering the bloodstream directly or via the skin or lungs.

Once a drug gets absorbed, the next stage of ADME is D, for distribution. Most often, the bloodstream is the vehicle for carrying medicines throughout the body. During this step, side effects can occur when a drug has an effect at a site other than its target. For a pain reliever, the target organ might be a sore muscle in the leg; irritation of the stomach could be a side effect. Drugs destined for the central nervous system face a nearly impenetrable barricade called the blood-brain barrier that protects the brain from potentially dangerous substances such as poisons or viruses. Fortunately, pharmacologists have devised various ways to sneak some drugs past the blood-brain barrier. Other factors that can influence distribution include protein and fat molecules in the blood that can put drug molecules out of commission by latching onto them.

After a medicine has been distributed throughout the body and has done its job, the drug is broken down, or metabolized, the M in ADME. Everything that enters the bloodstream — whether swallowed, injected, inhaled or absorbed through the skin — is carried to the body's chemical processing plant, the liver. There, substances are chemically pummeled, twisted, cut apart, stuck together and transformed by proteins called enzymes. Many of the products of enzymatic breakdown, or metabolites, are less chemically active than the original molecule. Genetic differences can alter how certain enzymes work, also affecting their ability to metabolize drugs. Herbal products and foods, which contain many active components, can interfere with the body's ability to metabolize other drugs.

The now-inactive drug undergoes the final stage of its time in the body, excretion, the E in ADME. This removal happens via the urine or feces. By measuring the amounts of a drug in urine (as well as in blood), clinical pharmacologists can calculate how a person is processing a drug, perhaps resulting in a change to the prescribed dose or even the medicine. For example, if the drug is being eliminated relatively quickly, a higher dose may be needed.
assistant
Can you give an example or two? Like the process of taking oral Prozac disperses throughout my body compared to getting a vaccine shot in my shoulder.
user
I am not a medical expert, but I can provide a general understanding of how Prozac and vaccines disperse through the body.

Prozac, also known as fluoxetine, is an oral medication that belongs to a class of drugs called selective serotonin reuptake inhibitors (SSRIs). It is typically used to treat depression, anxiety, and other related disorders. When you take Prozac, it is absorbed through the gastrointestinal tract and enters the bloodstream. From there, it is distributed throughout the body and eventually crosses the blood-brain barrier to reach the brain. In the brain, Prozac works by increasing the levels of serotonin, a neurotransmitter that helps regulate mood, sleep, and appetite.

On the other hand, vaccines are typically administered through injections, either intramuscularly (into the muscle) or subcutaneously (under the skin). When you receive a vaccine shot in the shoulder, it is usually an intramuscular injection. The vaccine is introduced directly into the muscle, where it is absorbed into the bloodstream. The immune system then recognizes the vaccine’s components as foreign and mounts an immune response, producing antibodies to protect against future infections.

In summary, Prozac and vaccines disperse through the body differently. Prozac is taken orally and absorbed through the gastrointestinal tract, while vaccines are usually administered through injections directly into the muscle or under the skin. Both substances enter the bloodstream and are distributed throughout the body, but they have different targets and mechanisms of action. Prozac primarily acts on the brain to increase serotonin levels, while vaccines stimulate the immune system to produce antibodies against specific pathogens. It is important to note that the specific dispersion and absorption rates of these substances can vary depending on factors such as individual metabolism, dosage, and formulation.
assistant
Are there any other drugs that act similarly to Prozac?
user
Yes, there are other drugs that act similarly to Prozac. Prozac belongs to a class of drugs called selective serotonin reuptake inhibitors (SSRIs), which work by increasing the levels of the neurotransmitter serotonin in the brain. Other drugs in this class include:

1. Zoloft (sertraline)
2. Paxil (paroxetine)
3. Celexa (citalopram)
4. Lexapro (escitalopram)
5. Luvox (fluvoxamine)

All of these drugs are used to treat depression, anxiety, and other mental health disorders. They work by blocking the reuptake of serotonin, which helps to increase the amount of serotonin available in the brain. However, each drug may have slightly different effects and side effects, so it's important to talk to your doctor about which one might be best for you.
assistant