You popped pills prescribed by the doctor to get relief from pain in some part of your body, what’s next? What happens to the medicine after it enters in our body? How does it make a way to identify and treat a particular site in the body?
Pharmacology is the branch of medicine that is concerned with the modes of action, uses and effects of the drugs.
Pharmacokinetics is one of the aspects of Pharmacology that deals with the study of the entire lifecycle of medicine inside our body.
Whether you are a medical student preparing for medical entrance exam or just a curious person, you are going to learn about the voyage of pills, potions and syrups in our body.
Four Stages of Pharmacokinetics
The lifecycle of medicine in our body is completed in following four phases. These stages are known as four stages of pharmacokinetics.
Absorption Þ Distribution ÞMetabolism Þ Excretion
There is an easy way to remember these four stages. You can collectively refer to these stages as ADME (Absorption, Distribution, Metabolism and Excretion).
The understanding of the lifecycle of medicine helps in designing medicines that can treat a disease, injury or condition completely, effectively and with minimum side effects.
The Absorption Stage
This stage starts with the administration of the medicine. Oral, intramuscular, intravenous, transdermal and subcutaneous are the most common ways to administer a medicine. When a medicine is administrated orally, it makes its way via special blood vessels. These blood vessels lead from the digestive tract to the liver. This is where the medicine is broken down. Directly administrating drug/medicine to the bloodstream, bypassing the liver and there are a few other ways for administrating medicine in the body.
The Distribution Stage
The bloodstream serves the purpose of a vehicle that carries medicines or drugs throughout the body. In this stage, sometimes the medicine targets the wrong site. This is the cause of side effects. For example, if you are experiencing pain in the leg, the medicine is designed to target a sore muscle in the leg. However, the pain reliever can cause irritation in the stomach as a side effect. Fat and protein molecules present in blood have an influence on the distribution of the medicine or drug. These molecules latch onto the drug/medicine and put it out of the commission.
The Metabolism stage
Once the distribution is done, the drug is metabolized or broken down. Everything entering the bloodstream is taken to the liver, the chemical processing plant of our body. In this plant, proteins called enzymes pummel, twist, cut down, stuck together and transform these chemicals. Many products obtained after enzymatic breakdown are chemically less active. Genetics also have an effect on the way enzymes work.
The Excretion stage
In this final stage, the removal of non-active drugs takes place via the feces or urine. A pharmacologist can actually calculate how the body of a person is processing drug or medicine. This can be done by measuring the percentage of the drug in urine. For example, if the amount of drug in urine is more than the expected, there is a need of giving higher doses or changes in the medicine.
Students preparing for medical entrance exams need to have the knowledge of the way medicines work inside our body. The best, easiest and quickest way of learning is practicing the maximum number of MCQs. You can visit a website providing medicine MCQs for practice. Smartphone applications like Synap allow students and teachers to create, share and practice medicine MCQs online. Download this app and learn more in less time.
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