HOW THE MEDICINES GET ABSORBED IN BODY AND ACT

HOW THE MEDICINES ARE ABSORBED IN BODY AND HOW THEY ACT ...
Pharmacology is the scientific field that studies how the body reacts to medicines and how medicines affect the body and pharmacokinetics which deal with understanding the entire cycle of a medicine's life inside the body.
Any Substances can enter the body through various means. Drugs can be smoked, snorted, inhaled, injected, swallowed as pills or capsules, or applied through trans dermal means (applied to the skin). Some substances can be eaten or drink, such as syrups and asava. Regardless of how a substance enters the body, it is carried through the bloodstream to various organs, including the brain. The method, by which a drug is administered, along with other factors, determines the speed of onset of effects.                                                                                                                                                                                          Drugs undergo four stages within the body:

1.            Absorption

2.            Distribution

3.            Metabolism

4.            Excretion

After a drug is administered, it is absorbed into the bloodstream. The circulatory system then distributes the drug throughout the body and brain. After the drug has shown its effect, then it is metabolized by the body. The drug is then excreted primarily through urine or faeces.

Step 1: Absorption
Absorption occurs after the substance is administered, but there are several different methods in which someone can use the medicine. The various routes of drug administration include:                                                                                     
Orally – by eating, drinking or swallowing pills ...                                                                                                    They are absorbed through the stomach and small intestine. The drug then passes into the bloodstream and travels to the liver before reaching the brain, a phenomenon known as the first-pass effect. Substances administered this way take effect more slowly than drugs taken via other routes, such as smoking or injection.                                                                                                                                                        Injection can be one of the fastest ways for substances to reach body tissues and organs through the bloodstream. Injection into the vein or the intravenous injection – delivers the substance directly into the bloodstream. Injection into the muscle allows the substance to be absorbed into the bloodstream through the muscle tissue and this is called an intramuscular injection. A subcutaneous injection is an injection into the fatty tissue underneath the skin, which enables the substance to be absorbed through the fatty tissue into the bloodstream. An intra dermal injection is an injection into the skin tissue.                                                                                                                                                                   Transdermal administration of some medicine is not as common as oral administration or injection, the essential or herbal oils are administered this way and are applied to the skin and then absorbed into the body. Once the drug is absorbed through the skin, it enters the bloodstream to be carried throughout the body and possibly to the brain.                                                                                                                              Some drugs can be inhaled as gases or fumes of medicines, Gases penetrate the lining of the lungs very quickly, which allows the drug to enter the bloodstream.                                                                                              Snorting drugs (essential oils to control snoring or running nose) causes them to be absorbed through the blood vessels in the nose where they enter the blood stream. This is similar to how buccal and sublingual drugs are absorbed. Buccal drugs are placed between a person’s gums and cheek ( like tobacoo), and sublingual drugs are placed under a person’s tongue. Buccal and sublingual drugs dissolve in the mouth and are absorbed through the tissue in the mouth to enter the bloodstream.
Step 2: Distribution                                                                                                                                                  
Distribution occurs via the body’s circulatory system. Once a drug has entered the bloodstream, the heart pumps the blood throughout the body, carrying the substance with it. This is how drugs can reach the brain. Before a drug can enter the central nervous system – the brain and spinal cord – it must pass through the blood-brain barrier. This is a system of tightly woven capillaries that is designed to prevent poisons and dangerous substances from reaching the brain. Drugs that are intended to act on the central nervous system are specially designed to pass through this barrier.                                                                                                                                           
Once the drug has reached the brain, it can have various effects, including the rush of euphoria or the “high” that is commonly associated with illicit drug use. Drugs accomplish this by affecting the chemicals and receptors within the brain. Many illicit drugs affect dopamine levels. Dopamine is a neurotransmitter that is responsible for feelings of pleasure and reward. Jatamansi and khas and vacha other smoothening essential oil work in this manner. Distribution is also responsible for the many negative side effects that drugs can have on the body. Because substances are carried to the entire body through the blood, they can have many effects that were unintended or unwanted. Illicit substances can damage the heart, liver, stomach, lungs, and other internal organs. Some of the effects of drugs use can be long-lasting or even permanent. That is why it is recommended to see the side effects of the medicines before prescribing it to the patient.
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.
Step 3: Metabolism
Once a drug has been distributed throughout the body, it is broken down or metabolized. The amount of time a drug stays in the body before being broken down varies between substances and methods of administration. All substances that enter the bloodstream, regardless of how they are administered, are eventually carried to the liver to be metabolized. Although the liver is the primary site of drug metabolism, drug metabolism may also occur in various other tissues and organs, such as the kidneys, lungs, skin, and other sites.
The liver metabolizes drugs through its enzymes, which break down and transform drugs into substances that can be expelled by the body. Drugs are metabolized into simpler molecules called metabolites that can be more easily excreted, typically through urine or faeces. These metabolites usually have less effect on the body. Some drugs, however, produce metabolites that can cause their own effects. After a medicine has been distributed throughout the body and has done its job, the drug is broken down, or metabolized. 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  pummelled with chemicals, 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.
Step 4: Excretion
The last phase of a drug within the body is excretion. This is the process by which drugs exit the body, primarily via urine or faeces. The metabolized drug travels from the liver to the bladder and large intestine, where waste products carry what is left of the drug out of the body. The now-inactive drug undergoes the final stage of its time in the body, excretion. This removal happens via the urine or faeces. 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.
Our body has a system that is smart enough to get medicines exactly where they're needed. Even though drugs travel in the blood throughout our body, each drug is designed to target certain protein molecules called receptors. In the case of a pain medication like guggulu, it search out specific receptors generated by pain and inflammation as they also course through the blood stream.  At the target spot for example it's pain in the knee and medicine is guggulu - the molecules latch onto the target receptors as they flow by and does their job of ceasing inflammation. Once the drug  hits the target and gets into the cell, this is when good things happen. The reactions between the drug and the target within the cell produce the desired effect on knee,  that would be a reduction of inflammation and pain.  As these drugs travel in blood, side effects can also be seen ,“Drug molecules also can bind to areas other than the target, especially if the two are closely related,”.
Administering drugs locally can decrease side effects and drug toxicity while maximizing a treatment's impact. For instance, topical antibacterial cream for a skin infection or a cortisone injection of a painful joint can avoid some of the side effects these medications create when they flow throughout the blood stream. Still, many medications can only be administered in a way that results in having them circulate through the entire body. “Plus, most of people prefer pills or capsules than shots.
The herbal medicines come from woody or herbaceous plants, have a different active principle, which gives them specific characters. These active principles have specific functions within the body. The phyto chemicals within herbs are secondary metabolites, which serve to protect the plants from damage by insects, animals, fungi, pathogens, and parasites. Most spices are dried before use, drying increases the shelf life and potency of herbs. The action of herbs within the body differs according to the ways that they are used, aiding digestion through the production of digestive enzymes. When mixed with digestive juices, these substances aid absorption. Such herbs have individual effects, their actions depending on the constitution of the person concerned and their disease. By their nature they add up in proper assimilation of medicine in body. Everyone must be knowing that extract of curcuma longa (haldi) has piperine (kalimirch ) in it for the better and quick assimilation in body.
Stay healthy and blessed
Dr. Inderjit Kaur                                                                                                                                                    9216777272