Pharmacokinetics Case

Think about taking a medication what does it do once it enters your body? How does your body know what the medication is for? Where does the medication go and how does it get to where it needs to be? These are a few of the questions you may ask yourself. Let's find out first off what is pharmacokinetics. Then how it works and finally some factors that may influence pharmacokinetics.

Pharmacokinetics what is it? "Pharmacokinetic, sometimes described as what the body does to a drug, refers to the movement of the drug into, though, and out of the body- the time course of its absorption, bioavailability, distribution, metabolism, and excretion" (The merk manual overview of pharmacokinetics, 2004). There are several factors that play a role on pharmacokinetics of a drug such as a patient's age, genetic makeup, and sex. Patients that are younger have a higher metabolism thus allowing the drug to metabolize quicker. On the other hand as patients start to age their metabolism starts to slow down and the drugs stay in their system longer. On the same token if a patient has a genetic disorder or disease this lowers their response time to a drug making it stay in their system longer. There is an acronym that scientists came up with to remember the key things to keep in mind when prescribing a drug to a patient it is LADME (Liberation, Absorption, Distribution, Metabolism, and Excretion).

"Liberation is the release of the drug from its dosage form (RxKinetics The LADME scheme, 2012). When a drug is introduced into the body it immediately starts to break down. Let's look at an oral medication first, when you swallow a pill it follows the gastrointestinal tract to the stomach where it mixes with stomach acids. The acids in our stomach begin to break the medication down and prepare it to move on to the next step of pharmacokinetics. Now let's look at what happens when we give or receive an injection. The medication is injected into our skin either subcutaneously, interdermally, intramuscularly. When the medication is injected or body must start to break the medication down on prepare it to be absorbed into the blood stream where it will continue with the process of pharmacokinetics. The only medication that reaches the blood stream immediately and does not go through the second step of pharmacokinetics is those that are given intravenously.

The second step in pharmacokinetics is absorption. "Absorption is the movement of the drug from the site of administration to the blood circulation" (RxKinetics The LADME scheme, 2012). After the drug is introduced into the body it needs to somehow make it to the blood circulation in order to get to where it is going. Think back to that medication that you took orally earlier that has reached your stomach, mixed with the acid, and began to break down. This medication has to reach the blood circulation somehow. What happens is the stomach contents continue to move into the small intestine. It is in the small intestine where the medication begins to be absorbed into the intestinal wall. Once it is absorbed into the intestinal wall it makes its way to the blood stream. The medication will have to cross several cell membranes on its journey to the blood stream which is why relief does not begin immediately upon taking a medication. Now think about the medication that was injected earlier. Depending on the type of injection it to may have many layers of cell membranes to be absorbed through to make it to the blood circulation.

Once the medication is absorbed into the blood circulation it can move onto the next step. This step is called distribution. "Distribution is the process by which drug diffuses or is transferred from the intravascular space to extravascular space (body tissues)" (RxKinetics The LADME scheme, 2012). Distribution is carried out by the blood circulation because blood travels to all of the tissues in our body. Once the medication reaches the blood circulation it will travel in the blood to its desired location. When the blood reaches the tissue in which the medication is intended for, the response to the drug will begin to take effect. With the movement of our blood at such a constant rate this process does not take long to carry out.

"Metabolism is the chemical conversion or transformation of drugs into compounds which are easier to eliminate." (RxKinetics The LADME scheme, 2012). In order for our body to excrete medications they need to be broken down within our body. This process begins when the drug enters our body. That medication that you orally begins to metabolize when it reaches your stomach. Your stomach acids break the medication down and whatever cannot be absorbed continues to breakdown as it follows your gastrointestinal tract through the body. Not all of a pill or injection that we take is used by our bodies. What our body needs from the medications are absorbed and distributed before they are excreted while the parts that our body cannot use continue to metabolize into smaller portions to be excreted.

This brings us to the last step in pharmacokinetics which is excretion. "Excretion is the elimination

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